MEMOIRES DU MUSEUM NATIONAL D'HISTOIRE NATURELLE

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Source: MNHN, Paris

Cover pholograph / Photographic tie couverture:

Semenoviceras fauna. Akmysh, North side of west Karatau, Mangyshlak. Late Albian (see Gaetani et at., this volume).

Faune a Semenoviceras. Akmysh. versant nord de I'ouest Karatau. Mangyshlak. Albien superieur (Gaetani et al., ce volume).

The Peri-Tethys Program, sponsored by international industries (AGIP, ARCO, BRGM, CHEVRON,

CONOCO. EAP(ELF), EXXON. SHELL, SONATRACH, TOTAL), research centres (CNRS, IFP), and a

university (UPMC), stalled in 1993. It examines the influence of Tethyan evolution on the bordering cratons

since its birth (through the break-up of Pangea), its life (by the extension and formation of oceanic seaways) and

finally its death (by collision between the main bordering plates which led to inversion within the epicratonic

basins).

Volumes deja parus /Previously published volumes-.

Peri-Tethys Memoir 1 (1994): Peri-Tethy an platforms. Proceedings of the IFP/Peri-Tethys Research Conference.

Technip. Paris: 1-275. ISBN: 2-7108-0679-7.

Peri-Tethys Memoir 2 (1996): Structure and Prospects of Alpine Basins and Forelands. Mem. Mus. natn. Hist,

not., 170: 1-550 (+ Atlas). ISBN: 2-85653-507-0.

Peri-Tethys Memoir 3 (1998): Stratigraphy and Evolution of Peri-Tethyan Platforms. Mem. Mus. natn. Hist,

nat., 177: 1-262. ISBN: 2-85653-512-7.

Peri-Tethys Memoir 4 (1998): Epicratonic Basins of Peri-Tethyan Platforms. Mem. Mus. natn. Hist, nat., 179:

1-294, ISBN: 2-85653-518-4.

Aussi /Also:

Peri-Tethys: stratigraphic correlations 1 (1997). 330 pp. Geodiversitas. 19 (2): 169-499. ISSN: 1280-9659.

Peri-Tethys: stratigraphic correlations 2 (1998). 224 pp. Geodiversitas , 20 (4): 515-738. ISSN: 1280-9659.

Source:

Peri-Tethys Memoir 4

Epicratonic Basins

of Peri-Tethyan Platforms

Source: MNHN, Paris

ISBN : 2-85653-518-4

ISSN : 1243-4442

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01970.

Source: MNHN, Paris

MEMOIRES DU MUSEUM NATIONAL D'HISTOIRE NATURELLE

TOME 179

GEOLOGIE

Peri-Tethys Memoir 4

Epicratonic Basins

of Peri-Tethyan Platforms

edited by

Sylvie Crasquin-Soleau (n & Eric Barrier 121

"’Universite Pierre et Marie Curie / CNRS

Departement de Geologie Sedimentaire

T15-25, E.4, case 104

4, Place Jussieu

F-75252 Paris Cedex 05

121 Universite Pierre et Marie Curie / CNRS

Departement de Geotectonique

T.25-26, E.l, case 129

4, Place Jussieu

F-75252 Paris Cedex 05

PUBLICATIONS SCIENTIFIQUES

DU MUSEUM

PARIS

1998

Source: MNHN, Paris

CONTENTS

SOMMAIRE

Pages

Northern Platform

1. The Upper Jurassic of the Volga basin: ammonite biostratigraphy and occurrence

of organic-carbon rich facies. Correlations between boreal-subboreal and

submediterranean provinces. 9

Pierre HANTZPERGUE, Frangois BAUDIN, Vassili MlTTA, Alexander OLFERIEV

& Victor Zakharov

2. Mesozoic of the Mangyshlak (West Kazakhstan). 35

Maurizio GAETANI, Marco BALINI, Valery J. VUKS, Vera A. GAVRILOVA,

Eduardo GarzaNTI, Alda NlCORA, Elisabetta ERBA, Elie CARIOU, FabrizioCECCA,

Isabella PREMOLI Silva, Maria Rose PETRIZZO, SimonettaClRILLI

& Raffaella BUCEFALO PALLIANI

3. Development and deformation of a Mesozoic basin adjacent to the Teisseyre-Tornquist

Zone: The Holy Cross Mountains (Poland). 75

Juliette LAMARCHE, Jolanta SWIDROWSKA, Frangoise BERGERAT, Maciej HaKENBERG,

Jean-Louis MANSY, Josef WlECZOREK, Ewa STUPNICKA & Thierry DUMONT

4. The Mid-Cretaceous events in eastern Europe: development and palaeogeographical

significance. 93

Evgenij J. BARABOSHKIN, Ludmila F. KOPAEVICH & Alexander G. OLFERIEV

5. Evolution of the eastern Fore-Caucasus basinduring the Cenozoic

collision: burial history and flexural modelling. 111

Andrei V. ERSHOV, Marie-Frangoise BRUNET, Anatoly M. NlKISHIN, Sergey N.

Bolotov, Maxim V. Korotaev & Svetlana S. Kosova

Southern Platform

6. Stratigraphic analysis of the Upper Jurassic (Oxfordian-Kimmeridgian) Antalo

limestone in the Mekele outlier (Tigrai, Northern Ethiopia): preliminary data. 131

Luca MARTIRE, Pierangelo CLARI & Giulio Pavia

Source: MNHN, Paris

PERI-TETHYS 4: F.PICRATONIC BASINS OF PERI-TETHYAN PLATFORMS

7. Stratigraphic and palaeogeographic survey of the Lower and Middle Jurassic along

a north-south transect in western Algeria. 145

Serge Elmi, Yves Almeras, M'Hamed Ameur, Jean-Paul BASSOULLET,

Mohained BOUTAKIOUT, Miloud BENHAMOU, Abbes Marok, Larbi MEKAHLI,

Abderrahmane MEKKAOUI & Rene MOUTERDE

8 . The Jurassic of the southern Levant. Biostratigraphy, palaeogeography

and cyclic events. 213

Francis HlRSCH, Jean-Paul BASSOULLET, ElieCARIOU, Brian CONWAY. Howard

R. Feldman. Lydia Grossowicz, Avraham Honigstein, Ellis F. Owen

& Amnon ROSENFELD

9. The central High-Atlas (Morocco). Litho- and chrono-stratigraphic correlations

during Jurassic times between Tinjdad and Tounfite. Origin of subsidence.237

Andre POISSON. Majid HADRI, Ahmed MlLHI, Myriam JULIEN & Jean ANDRIEUX

10. The Permian basins of Tiddas, Bou Achouch and Khenifra (central Morocco).

Biostratigraphic and palaeophytogeographic implications. 257

Jean BROUTIN. Habiba AaSSOUMI, Mohammed El WARTITI, Pierre FREYTET,

Hans Kerp, Cecilio Quesada & Nadege Toutin-Morin

Index.279

Source: MNHN, Paris

The Upper Jurassic of the Volga basin: ammonite

biostratigraphy and occurrence of organic-carbon

rich facies. Correlations between boreal-subboreal

and submediterranean provinces

Pierre HANTZPERGUE Frangois BAUDIN (2 >, Vassili MlTTA l3 \

Alexander OlFERlEV w & Victor ZAKHAROV ,5 >

"’Universite Claude Bernard, Centre des Sciences de la Terre. CNRS-UMR 5565

27-43, boulevard du 11 Novembre, F-69622 Villeurbanne Cedex, France

i2i CNRS-ESA 7073 & FR32, Departement de Geologie Sedimentaire, Universite Pierre et Marie Curie

case 117. 4 place Jussieu, F-75252 Paris Cedex 05. France

111 Research Geological Oil Institute, VNIGNI, Shosse Entuziastov 36, 10581 Moscow, Russia

<4) Geosintez, Washavskoje Shosse 39A, 113525 Moscow, Russia

<5> Institute of Geology and Geophysics, Siberian Branch ofAcademy of Science, Novosibirsk 90, Russia

ABSTRACT

A detailed litho-biostratigraphic succession of the Upper Jurassic deposits of the middle Volga basin is described using six

sections, including the lectostratotype of the Volgian. A new biostratigraphic scheme, displaying nineteen ammonite zones, is

completed for the Russian Platform. Many biostratigraphic equivalencies between the Russian Platform and both the boreal-

subboreal and the submediterranean provinces arc proposed and discussed. Seven common horizons (Pictonia densicostata,

Piclonia baylei, Orthaspidoceras lallierianum, Aspidoceras caletanum, Aulacostephanus contejeuni, Aulacostephanus yo and

Aulacostephanus autissiodorensis) are recognized for the Kimmeridgian Stage, that allow a remarkably precise correlation

between the Russian Platform and the western european area. The equivalencies between Volgian, Portlandian and Tithonian

are discussed. Correspondences can be only suggested by affinities of the endemic russian ammonites and the boreal faunas. Up

to now, the local scheme appears still necessary. Bulk geochemical characterization of the Upper Jurassic series from the

Russian Platform shows six main intervals with high organic content (Corg. >10%) and good petroleum potentials.

Nevertheless, the stratigraphical distribution of black shales of the Russian Platform is different from those of the Kimmeridge

Clay Formation. This clearly indicates that oil shale bands cannot be taken as marker beds at a large scale.

HANTZPERGUE, P„ Baudin, F„ Mitta, A., Olfertev, A. & Zakharov, V., 1998. — The Upper Jurassic of the Volga basin:

ammonite biostratigraphy and occurrence of organic-carbon rich facies. Correlations between boreal-subboreal and

submediterranean provinces. In: S. Crasquin-Soleau & E. Barrier (eds), Peri-Tethys Memoir 4: epicratonic basins of Peri-

Tethyan platforms, Mem. Mus. natn. Hist. not.. 179 : 9-33. Paris ISBN : 2-85653-518-4.

Source: MNHN, Paris

PIERRE HANTZPERGUE ETAL.

RESUME

Le Jurassique superieur du bassin de la Volga: biostratigraphie des ammonites et distribution des facies riches en

carbone organique. Correlations entre les provinces boreale-subboreale et submediterraneenne.

Une description litho-biostratigraphique detaillee des depots du Jurassique superieur de la moyennc vallee de la Volga est

etablie a partir de six coupes, dont celle du lectostratotype du Volgien. Une nouvelle succession des faunes d'ammonites,

comprenani dix-neuf zones, est proposde pour la plate-forme russe. De nombreuses correlations entre les echelles

biostratigraphiques de la plate-forme russe et celles des provinces boreale-subboreale et submediterraneenne sont proposees et

discutees. Sept horizons ( Pictoria densicostata, Pictonia baylei, Orthaspidoceras lallierianum, Aspidoceras caleianurn,

Aulacosiephanus contejeani, Aulacostephanus yo et Aulacostephanus aulissiodorensis) sont communs pour le Kimmeridgien,

ce qui permet des correlations tres precises entre la plate-forme russe et I'Europe occidentale. Les equivalences entre Volgien,

Portlandien et Tithonien sont discutees. Des correspondances peuvent juste etre suggerdes compte tcnu des affinites entre les

faunes endemiques russes et les faunes boreales. L’utilisation d’un schema biostratigraphique local est encore ndcessaire & ce

niveau de I'etude. La caracterisation geochimique globale de la sdrie du Jurassique de la plate-forme russe montre six

intervalles principaux d'enrichissement en matiere organique (Corg. > 10%), avec d’excellents potentiels petroliers. La

distribution stratigraphique des black shales de la plate-forme russe est diffcrente de celle des principaux intervalles riches en

matiere organique de la Formation de Kimmeridge Clay. Ceci indique clairement que ces “bandes organiques” ne peuvent etre

utilisees comme des marqueurs lithostratigraphiques & une grande echelle.

INTRODUCTION

During Upper Jurassic, precise stratigraphical correlations present many difficulties because of the

well known provincialism of ammonite faunas. They become acute progressively from the middle

Oxfordian to the Tithonian, and it is necessary to separate schemes of standard ammonites zones for

each province and to describe the succession that are to be correlated.

In the Russian Platform, the dominant faunas present boreal or sub-boreal affinities during the

Oxfordian and lower Kimmeridgian times. Progressively, endemic ammonites occur in upper

Kimmeridgian and in the Volgian faunal sequence.

Correlations with the primary standard of reference of the submediterranean province are the most

imprecise. In the recent compilation of the parallel ammonites scales for tethyan northern margin

(Cariou et ai, 1997; HANTZPERGUE et al., 1997; GEYSSANT. 1997), the equivalence with russian faunal

sequences was not taken into consideration. On the contrary, the faunal affinities between Oxfordian

and/or Kimmeridgian of the Russian Platform allow best correlations with boreal and sub-boreal

provinces. But the "Volgian province” named by Nikitin (1881a) for the condensed and incomplete

uppermost Jurassic sequences require a local faunal scheme. The established ammonite succession in the

middle Volga basin should provide useful alternative standard of reference in an area in which another

standard cannot be easily applied.

Though most of the sedimentary rocks contain dispersed organic matter from different origins, only a

few of them can be considered as organic-rich (> 5% Corg.). Those having a high amount of marine

organic matter (> 10 % Corg.) appropriate to generate hydrocarbons and presenting a high degree of

immaturity can be considered as “oil shales”. Such facies are widespread distributed in the Upper

Jurassic succession of the Russian Platform.

The purpose of this paper is to precise the litho-biostratigraphic succession of Upper Jurassic of the

Russian Platform, to propose correlations with other Late Jurassic ammonite zonations and to situate the

black shales deposits in the stratigraphic framework in order to check their possible synchronicity with

the main organic-rich intervals from the North Sea area.

Sections

Five sections were studied in the Moscow basin and the Ulyanovsk-Saratov trough along the Volga

River (Fig. 1). The precise location of each section is given in Fig. 2:

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

1 1

Fig. 1.— Jurassic outcrops of the Russian Platform and location of the studied sections.

Fig. I .— Affleurements jurassiques sur la plate-forme russe et localisation des coupes etudiees.

Source: MNHN, Paris

Aral Sea

PIERRE HANTZPERGUE ET AL.

— the Oxfordian deposits are detailled in the sections described by NIKITIN (1884) near the town of

Makariev on the Unzha River (Fig. 2A). They consist of 5.90 m grey to dark clays with a characteristic

horizon of bituminous shales in the middle part and phosphatic pebbles in the upper part. The Makariev

section ends with the base of the Kimmeridgian Stage;

— the Kimmeridgian crops out on the waterside of the Kuibyshev reservoir (Volga River, 25 km

north of the town of Ulyanovsk), north-east of Undory, between Dubky and Mimei localities (Fig. 2B).

It is a thick alternance (54 m and visual gap) of marls and argillaceous limestones containing only one

black shales horizon;

— the Volgian Formation are studied in the shore of the Kuibyshev reservoir, between Gorodische

village and Dubky locality (Undory village. Fig. 2B). This section corresponds to the Volgian

lectostratotype proposed by GERASSIMOV & Mikhailov (1966). The upper Volgian Formation is also

described in Kashpir, directly south of Syzran, on the Kuibyshev reservoir (Fig. 2C). It corresponds to

18 m of terrigenous deposits, argillaceous in the lower part and sandy in the upper part, with

intercalations of four major black shales horizons.

Biostratigraphical elements

Ammonites were collected bed by bed which allow to characterize the faunal succession for the

Upper Jurassic of the middle Volga basin. The observed scheme shows three major biogeographic

influences and requires the use of three different zonal scales:

— the Oxfordian Zones are used throughout the boreal province which extends from northern Britain

to Greenland through Spitzbergen into the Russian Platform. This scheme is based on Cardioceratids

faunas;

— the Kimmeridgian zonal scheme is that of subboreal province which extends from southern

Britain across Poland and the middle Volgian basin. Aulacostephanids are the dominant elements.

Endemic ammonites of the Franco-German Bioma (HANTZPERGUE, 1989) occur in this subboreal faunal

sequence and are common elements between Russian and western european series.

The endemic Volgian ammonites belong to a biogeographic unit which extends from northern

Siberia, Russian Platform and Poland across the circum-Arctic shelf, including Barents shelf and

northern Canada. This faunal sequence can be compared to the English zonal standard based on boreal

Perisphinctids. The correlations with the Tithonian stage are hypothetical (GEYSSANT, 1997); only the

genus Gravesia allows, according to MESEZHNIKOV et al. (1984) an equivalence between the base of the

Submediterranean Tithonian and the lowermost beds of the “English upper Kimmeridgian”.

Organic matter data

All the 175 collected rock-samples were open air-dried and crushed in a metallic mortar to obtain a

fine (2 |im) powder. Calcium carbonate content (% CaCO,) was measured using a calcimetric bomb.

The total carbon content (% Ctot.) was measured using a WR 12 LECO analyser. The organic carbon

content (% Corg.) is estimated as the difference between total carbon and mineral carbon, assuming that

all the mineral carbon is represented by pure calcite. The C org. concentration describes the quantity of

organic carbon, although it should be kept in mind that organically bound hydrogen, oxygen, nitrogen

and sulphur can contribute up to 50% of the total sedimentary organic matter. In immature samples, 1

wt% C org. corresponds to 1.5 to 2.0 wt% organic matter. The source and thermal maturation of the

organic matter were estimated on 65 samples using a Rock-Eval instrument (ESPITALIE et al., 1985-86).

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

Fig. 2.— Precise location of the studied sections.

Fig. 2.— Localisation precise des coupes etudiees.

UPPER JURASSIC SYNTHETIC SECTION OF THE VOLGA BASIN

Oxfordian: Makariev section (Mk.) (Fig. 3)

Lower Oxfordian

Cordatum Zone d'ORBlGNY (1852).

Mk 16- Compact grey clays, highly bioturbated, showing a 10 to 20 cm-thick bedding with planar

surfaces. Centimetric phosphatic nodules are present, and large pieces of wood occur at 20 cm from the

Source:

PIERRE HANTZPERGUE ETAL.

bottom. Pleuromia sp., Dentalium sp., Astarte sp., Entolium sp., Nuculoma sp., Oxytoma sp.,

Grammatodon sp., rhynchonellids, belemnites and Cardioceras (Cardioceras) gr. cordatum (Sow.),

Cardioceras sp., Perisphinctes sp. 1.40 m.

Middle Oxfordian

Densiplicatum Zone Sykes (1975) and Tenuiserratum Zone Cariou (1966).

Mk 15- compact grey clays, bioturbated, starting with a 10 to 15 cm-thick layer rich in glauconite and

containing a lot of reworked and non-oriented belemnites. The boundary with the previous unit is

underlined by a thin level with crushed ammonites. A lumachellic bed with ammonites, belemnites,

gastropods ( Pleurotomaria sp.) and bivalves ( Gryphaea dilatata, Cosmetodon sp.) occurs 40 cm below

The top. The top of this unit is marked by a yellowish to greenish 10 cm-thick layer of argillaceous

pyritic sand with belemnites. Cardioceras (Subvertebriceras) densiplicatum Boden, Cardioceras

(Plasmatoceras) tenuistriatam Borissiak, Cardioceras (Plasmatoceras) popilaniense Boden,

Cardioceras (Subvertebriceras) zenaidae Ilov., Cardioceras (Plasmatoceras) tenuicostatum (Nik.),

Cardioceras (Maltoniceras) kokeni Boden, Cardioceras cf. mauntjoi Freb. and in upper part:

Cardioceras (Subvertebriceras) zenaidae Ilov., Cardioceras (Cawtoniceras) tenuiserratum (Oppel),

Perisphinctes (Arisphinctes) gr. plicatilis (Sow.). 1.80 m.

Upper Oxfordian

Glosense Zone SYKES (1975).

— Ilovaiskii Subzone SYKES (1975).

Mk 14- finely laminated black shales, with some planar traces (trails?) at the bottom. Gastropods

( Aporrhais , Dicroloma), bivalves ( Entolium sp.) and ammonites: Amoeboceras ilovaiskii (Sok.),

Amoeboceras alternoides (Nik.), Perisphinctidae ind. 0.12 m.

Mk 13- black bioturbated clays (Chondrites) with a thin layer of crushed ammonites, bivalves and

gastropods at 2 cm from the base. Rare pieces of crinoids at the top. Amoeboceras ilovaiskii (Sok.),

Amoeboceras alternoides (Nik.), Perisphinctidae ind. 0.15 m.

Mk 12- grey silty clays with Trautscholdia cordata and debris of ammonites: Amoeboceras alternoides

(Nik.), Amoeboceras transitorium Spath, Amoeboceras cf. glosense (Bigot & Brasil), Amoeboceras

ilovaiskii (Sok.). 0.30 m.

Serratum Zone SYKES (1975).

— Koldeweyense Subzone Sykes (1975).

Mk 1 Id- compact grey clays with belemnites: Pachytheutis panderiana (d'Orb.), Hibolites sp. and

ammonites: Amoeboceras alternoides (Nik.), Amoeboceras cf. damoni Spath, Amoeboceras cf.

koldeweyense Sykes & Callomon, Amoeboceras ilovaiskii (Sok.). 0.30 m.

Mk 1 lc- greenish clays having a yellowish to rust-coloured alteration, containing pyritic and phosphatic

nodules, glauconite, belemnites and ammonites: Amoeboceras koldeweyense Sykes & Callomon,

Amoeboceras gr. serratum (Sow.), Amoeboceras cf. talbejense Kal. & Mesezhn. 0.10 m.

— Serratum Subzone SYKES (1975).

Mk lib- compact grey clays with: Amoeboceras cf. ovale (Quenst.), Amoeboceras cf.

tuberculatoalternans (Nik.), Amoeboceras gr. serratum (Sow.). 0.10 m.

Mk 11a- greenish clays having a yellowish to rust-coloured alteration, containing bivalves ( Buchia ,

Meleagrinella, Astarte ) and belemnites. 0.08 m.

Mk 10b- grey clays becoming glauconitic to the top with belemnites, bivalves ( Trautscholdia cordata),

and Amoeboceras cf. ovale (Quenst.), Amoeboceras gr. serratum (Sow.). The upper surface is

bioturbated and burrows filled by the glauconitic clays. 0.20 m.

Source: MNHN. Paris

UPPER JURASSIC OF THE VOLGA BASIN

OXFORDIAN

<3 6

4 7

s 12

* 13

Fe 2

-o. 14

Cl 3

fe 9

Y 15

Ph 4

1 0

Py 5

4^17

Limestones

Argilaceous limestones

Marls

Clays

Silty clays

Laminated clays

Black shales

Sandstones

Sand-silts

N-W EUROPEAN

(Sub-Boreal pars)

Zones & Subzones

VOLGA BASIN

Zones & Subzones

L. Kim.

U. Oxl.

M. Oxl.

L.Oxf.

Callouian

_'■ <—>• biogeographical communication

h-- -?V=F Xn g

75M py

s-xt-

g ^ Cymodoce Zone

“!'■* M—g M —R. cf. Cymodoce

-'■fc. k ^.Ph.GI

!r- i^Gi.Phg y 6/f til: BStScmtata Baylei Zone

^ Gl @ ys Y -4-H. Frequens

~j~ g, Ph ♦^Gl Regulars & Rosenkrantzi Zones

i~- ^7 Gl j 4 Serratum Zone

0 _ O Z, ^ O

Pya' 3 05 Glosense Zone

*bs J

Cl 4 Densiplicatum Zone

Ph &> <3 / Cordatum Zone

10m —

Makarlev

Fig. 3.— Oxfordian lithostratigraphy and biostratigraphy: Makariev (Mk) section. 1. Nodules: 2, Oxidized surface; 3.

Glauconite; 4. Phosphate; 5. Pyrite; 6, Ammonite; 7. Belemnite; 8. Bivalve; 9, Gastropod; 10. Brachiopod; 11, Crinoid;

12. Serpule; 13. Bioturbation; 14. Trail; 15, Larges wood fragments; 16, Fish; 17, Vertebrates remains.

Fig. 3 .— Lithosiraligraphie el biostratigraphie de I'Oxfordien : coupe de Makariev (Mk). I. Nodules : 2. Surface oxydee ; 3,

Glauconie ; 4. Phosphate ; 5, Pyrite : 6. Ammonite ; 7. Belemnite ; 8. Bivalve : 9. Gasteropode ; 10. Brachiopode ; 11.

Crino'ide ; 12, Serpule ; 13. Bioturbation ; 14, Piste ; 15, Grands fragments de bois ; 16, Poisson ; 17, Restes de

vertebres.

Source: MNHN, Paris

PIERRE HANTZPERGUE ETAL.

Regulare and Rosenkrantzi Zones SYKES (1975).

Mk 10a- grey clays with phosphatic pebbles, becoming intensely biotubated with reworked belemnites

at the top. Amoeboceras cf. ovale (Quenst.), Amoeboceras tuberculatoalternans (Nik.), Amoeboceras cf.

lineatum (Quenst.), Amoeboceras gr. serratum (Sow.), Amoeboceras gerassimovi Kal. & Mesezhn.,

Amoeboceras cf .freboldi Spath, Amoeboceras leucum Spatli 0.40 m.

Mk 9b- grey clays with ammonites, belemnites and some phosphatic concretions at the top.

Amoeboceras cf. lineatum (Saif.). 0.40 m.

Mk 9a- glauconitic clays with phosphatic concretions, belemnites, bivalves and serpulids. Floated wood

appears on the upper surface of this unit. 0.05 m.

Mk 8d- grey clays with belemnites and ammonites: Amoeboceras cf. lineatum (Saif.) and Ringsteadia

ci.frequens Saif, at the top. 0.50 m.

KIMMERIDGIAN (Fig. 4)

Lower Kimmeridgian: Makariev(Mk) and Mimei village (Ta) sections

Baylei Zone SALFELD (1913).

Mk 8c- glauconitic and ferrugineous clays with phosphatic nodules, bivalves ( Nuculoma sp.), belemnites

and ammonites: Pictonia densicostata Salfeld. 0.05 m.

Mk 8b- grey clays with ammonites ( Pictonia baylei Salfeld) appearing at 20 cm from the base.

Amoeboceras (Amoebites) cf. kitchini (Salfeld), Amoeboceras sp., Desmosphinctes cf. mniovnikensis

Nik. 0.50 m.

Mk 8a- altered glauconitic clays with oyster fragments, phosphatic nodules and small crystal of

(secondary ?) gypsum. 0.05 m.

Cymodoce Zone DOUVILLE (1881).

Mk 7b- dark laminated clays with belemnites, fish-scales, gastropods (Aporrhais) and bivalves ( Loripes

sp., Nannogyra sp.), Perisphinces sp. juv. 0.50 m.

Mk 7a- glauconitic clays with nodules and large crushed ammonites and oysters. 0.05 m.

Mk 6c- grey clays having a cubic cutting up. 0.20 m.

Mk 6b- dark laminated clays with bivalves ( Loripes sp.). 0.10 m.

Mk 6a- grey clays with large shells of ammonites: Rasenia cf. uralensis (d'Orb.) and Rasenia cf.

cymodoce (d’Orb.). 0.30 m.

Mk 5- dark laminated clays, Amoeboceras (Amoebites) gr. kitchini (Saif.) 0.20 m.

Mk 4- clays having a cubic cutting up and containing large crushed shells of ammonites (Amoeboceras

sp.) and bivalves (Nuculoma sp. ind.). 0.70 m.

Mk 3- dark laminated clays with Rasenia sp. 0.30 m.

Mk 2- grey clays, deeply altered toward the top, with rare ammonites, belemnites at the base, bivalves

(Nuculoma sp.) and phosphatic nodules at the top. 1.10 m.

Mk lc- grey clays, bioturbated near the bottom, with numerous shelly debris (ammonites, bivalves) at

the middle part. Centimetric limestone nodules appear 30 cm below the top. Amoeboceras cf. cricki

(Saif.). 1.80 m.

Source . MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

Makariev

WESTERN-EUROPE

(FrancQ-goiman Blom)

VOLGA BASIN

Zones A Subzones

Zones A Subzonee

Fe 2

Q 3

Ph 4

Py 5

0 6 s 12

t 1 13

■or 8 14

iflm

AuUsslo-

Fa Ilex

dorensks

AuUsslodorensto -►

Autlsslodofensla

& 9 y 15

xulO o>i16

Conte)osnl * >

Contejeanl

Eudoxus

Cstetsmm ^^ ^

Calotanum

Orthocera

Limestones

Mulebllts

Lellierlsnum -*-

Mulebllls

©LolManlJIlS

Argilaceous

limestones

Mu ta bills

Marls

Clays

Chatolalllonenele

Silly clays

Laminated days

Cymodoce

Achilles -_,_

Cymoooco

Black shales

Sandstones

Cymodoce -<-►

Cymodoce

Sand-silts

Baytcrl

BayWH -4-►

Oenslcoslste ^->■

tyiei

Pseudoscylhica Z.

Sokolovi Z.

Klimovi Z ?

Autissiodorensis Z.

(y Aulissiooorsnso

/I -V

Eudoxus Z.

Q H.YO

3 - 4 -H.YO

3 4- w Cooloioant

(?) h Calrtanum

Kameny Ourag

Dubky

probable faunal gap

biogeographical

communication

Fig. 4.— Kimmeridgian lithostratigraphy and biostraligraphy: Makariev (Mk). Mimei village (Ta), Dubky (Du) and Kameny

Ourag (KO) sections.

Fig. 4.— Lithostratigraphie el biostratigraphie du Kimmeridgien : coupes de Makariev (Mk). Mimei village (Ta). Dubky (Du)

et Kameny Ourag (KO).

Source: MNHN, Paris

PIERRE HANTZPERGUE ETAL.

Mk 1 h- grey micritic limestone with a rust-coloured alteration in the middle part containing Rasenia cf.

uralensis (d’Orb.) at the top. 0.20 m.

Mk la- clays, deeply altered by the proximity of soil. 0.40 m.

Hiatus.

Ta 1- grey marls with phosphatic nodules. At the bottom, large debris of wood. Bivalves: Buchia

concentrica, Malletia sp., and ammonites: Rasenia cf. uralensis (d’Orb.), Amoeboceras sp. At the top.

ammonites, Rasenia cf. cymodoce (d’Orb.) and belemnites. 2.00 m.

Ta 2- grey marls with phosphatic nodules and ammonites (Perisphinctids). The base is marked by a

more or less continuous level of whitish nodules. 0.30 m.

Ta 3- grey argillaceous limestone, intensely bioturbated. 0.20 m.

Ta 4- grey marls becoming darker to the top. 1.60 m.

Ta 5- brownish finely laminated black shales with planar traces (trails ?) and rare fauna of brachiopods

and gastropods ( Meleagrinella, Aporrhais sp.). 0.50 m.

Ta 6- dark-grey platy argilaceous limestones with pyritic nodules. 0.45 m.

Ta 7- dark-grey laminated marls. 0.03 m.

Ta 8- light-grey marls. 0.40 m.

Ta 9- greyish to brownish laminated clays. 0.10 m.

Ta 10- dark-grey laminated clays. 0.70 m.

Ta I 1- light-grey argillaceous limestones. 0.75 m.

Ta 12- marls more or less laminated. 0.25 m.

Ta 13- grey to beige argillaceous limestones. 1.10 m.

Ta 14- compact beige argillaceous limestones. 0.70 m.

Ta 15- grey to beige platy marls. 0.70 m.

Ta 16- grey marls. 0.80 m.

Ta 17- compact beige marls. 1.10 m.

Ta 18- light-beige argillaceous limestones containing rare Lingula sp. 2.00 m.

Ta 19- light-grey argillaceous limestones. 0.50 m.

Ta 20- marls, deeply altered due to the proximity of soil. 1.50 m.

Hiatus.

Upper Kimmeridgian: Dubkyand Kamenyi Ourag sections (Du and Ko)

Hiatus.

Eudoxus Zone Neumayr (1873).

Ko I - grey argillaceous limestones with belemnites and ammonites: Pararasenia hybridus Ziegler,

Aspidoceras caletanum (Opp.). 0.50 m.

Ko 2- greyish to greenish silty clays with planar burrows, numerous fish-scales and remains. 0.40 m.

Ko 3- grey marls. 1.00 m.

Du 1- light-grey argillaceous limestones containing some ferrugineous nodules with belemnites and

ammonites: Aulacostephanus eudoxus (d’Orb.), Aspidoceras caletanum (Opp.), Aspidoceras gr.

longispinum (Sow.), and Amoeboceras sp. 0.60 m.

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

Dii 2- marls containing light-grey calcareous lenses and numerous limonitic ammonites:

Aulacostephanus contejeani (Thur.), Aspidoceras quercynum Hantzpergue, and Tolvericeras

sevogodense (Contini & Hantzpergue). 0.50 m.

Du 3- marls containing light-grey calcareous lenses and numerous limonitic ammonites:

Aulacostephanus yo (d'Orb.), Aspidoceras gr. quercynum Hantzpergue. 0.50 m.

Du 4- light-grey marls containing some calcareous nodules and small belemnites. A 50 cm thick more

clayey bed lies 2 m from the base. Ammonites, Aspidoceras sp. and Aulacostephanus cf. yo (d'Orb.)

appear at 3 m and 4 m. The top of this units is marked by a layer of calcareous nodules. 4.00 m.

Du 5- beige massive argillaceous limestones, with rare phosphatic nodules, becoming grey and marly

within the uppermost 1 m. Aptychus ( Laevaptychus ), belemnites, brachiopods (Zeillerids), bivalves

(Loripes) and large pyritic disc containing ammonites: Aspidoceras sp. and Aulacostephanus cf .yo

(d'Orb.). 4.00 m.

Du 6- grey to beige bioturbated marls and argillaceous limestone with calcareous nodules containing

ammonites, Tolvericeras gr. sevogodense (Contini & Hantzpergue). 5.00 m.

Autissiodorensis Zone ZIEGLER (1961).

Du 7a- beige argillaceous limestones becoming marly in the topmost 50 cm. Amoeboceras sp.,

Aulacostephanus autissiodorensis (Cotteau), Aulacostepanus kirghisensis (d’Orb.), Aulacostephanus

vo I gens is (d'Orb.), Aulacostephanus undorae (Pavl .), Amoeboceras (Nannocardioceras) volgae (Pavl.),

Amoeboceras (Nannocardioceras) subtilicostatum (Pavl.), Sutneria sp., Virgataxioceras sp. 4.50 m.

Du 7b 1- grey to grey-greenish marls with phosphatic nodules and pyritic disc. 2.00 m.

Du 7b2- alternation of dark-grey to light-grey marls with ammonites: Aulacostephanus autissiodorensis

(Cotteau), Aulacostephanus kirghisensis (d'Orb.), Aulacostephanus volgensis (d Orb.), Aulacostephanus

undorae (Pavl.), Virgataxioceras fallax (Ilov.). 2.00 m.

Du 8- grey to light-beige argillaceous limestone with ammonites: Aulacostephanus autissiodorensis

(Cotteau). Aulacostephanus kirghisensis (d'Orb.), Aulacostephanus volgensis (d'Orb.), Aulacostephanus

undorae (Pavl.). Virgataxioceras fallax (Ilov.) 2.20 m.

Du 9- alternation of dark-grey to light-grey marls with ammonites concentrated at the base of dark-grey

beds, Aulacostephanus autissiodorensis (Cotteau), Virgataxioceras fallax (Ilov.), small Aspidoceras (?)

and Sutneria sp. 4.50 m.

VOLGIAN (Fig. 5)

Lower Volgian: Dubky section (Du)

Klimovi Zone Mikhailov (1962 a).

Ammonite fauna, after MESEZHNIKOV et al. (1984): Ilowaiskya klimovi (Ilov & Flor .) Gravesta cf.

gigas (Zieten), Gravesia cf. gravesiana (d'Orb.) Neochetoceras cf. steraspis (Opp.), Glochiceras ct.

lithographicum (Opp.) and Sutneria cf. subeumela (Schneid).

Du 10a- grey clay with phosphatic nodules at the base. Ilowaiskya klimovi (Ilov.), Neochetoceras sp.,

Glochiceras sp. 0.80 m.

Sokolovi Zone ILOVAISKY & FLORENSKY (1941).

Ammonite fauna, after MESEZHNIKOV (1988): Ilowaiskya sokolovi (Ilov. & Flor.), Ilowaiskya pavida

(Ilov. & Flor.), Sutneria sp., Haploceras cf. elimatum (Opp.), Glochiceras (Paralmgulaticeras) ct.

lithographicum (Opp.), Glochiceras (Paralingulaticeras ) cf. parcevali (Font.)

PIERRE HANTZPERGUE ETAL.

U. Volg.

M. Volg.

VOLGIAN

Ryazanian

Valanginian

FulgensZ

NMiri 2.

• NodigerZ.

0 ^— SubdilusZ.

# 1— FulgensZ.

NikHiniZ.

•*- Pander! Z.

Gorodische

Limestones

Argilaceous limestones

Marls

Clays

Silty clays

Laminated clays

Black shales

Sandstones

Sand-silts

6 6

s 12

• 1

d 7

2. 13

Fe 2

-O' 8

w 14

Gl 3

& 9

Y 15

Ph 4

ut>10

<X>a1 6

PY 5

<2tf17

l—

Kashplr

ENGLAND

Zonss

Lamplughl

Prapllcomphalua

Prlmltlvua

Oppraaaua

Angulformia

Karberua

Okuasnsla

Glaucollthus

Albani

Flttonl

Rotunda

Pallas lo idea

Pactlnatua

Hudloatonl

Whoatleyenala

ScHulua

Elegana

VOLGA BASIN

Zones & Subzones

Nodlg er

Paeudoacythlca

\\^\\ probable faunal gap

-*—*• biogeographical communication

Fig. 5.- Volgian lithostratigraphy and biostratigraphy: Dubky (Du). Gorodische (Go) and Kashpir (Ka) sections.

Fig. 5.— Lithostratigraphie el biostratigraphie du Volgien : coupes de Dubky (Du). Gorodische (Go) el Kashpir (Ka).

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

Du 10b- dark-grey clay with small carbonates nodules, Ilowaiskya sokolovi Ilov., Ilowaiskya pavida

Ilov. 1.00 m.

Pseudoscythica Zone Ilovaisky & Florensky (1941).

Ammonite fauna, after MESEZHNIKOV (1988): Ilowaiskya schaschkovae (Ilov. & Flor.), Ilowaiskya

pseudoscythica (Ilov. & Flor.), Pectinatites ianschini (Ilov.), Pectinatites tenuicostatus Mikhailov,

Glochiceras sp., Sutneria sp., Haploceras sp.

Du. 10c- grey clay with ammonites and belemnites concentrated at the top, Ilowaiskya pseudoscythica

Ilov., Ilowaiskya pavida Ilov. 0.80 m.

MIDDLE VOLCIAN: GORODISCHE (GO) AND KASHPIR(Ka) SECTIONS

Panderi Zone ROZANOV (1906).

Ammonite fauna, after MESEZHNIKOV et at. (1984) and MlTTA (1993): Dorsoplanites dorsoplanus

(Vischniakoff), Dorsoplanites panderi (d'Orb.), Pavlovia pavlovi (Michalski), Zaraiskites scythicus

(Vischniakoff), Zaraiskites michalskii Mitta, Zaraiskites quenstedti (Rouillier & Fahrenkohl),

Zaraiskites tschernyschovi (Michalski), Zaraiskites zarajskensis (Michalsky), Acuticostites acuticostatus

(Michalski), Acuticostites bitrifurcatus Mitta.

Go 9a- grey marls, intensely bioturbated (Chondrites), with pyrite concretions. Perforated calcareous

nodules occur at the base, ammonites and belemnites at the top. 0.20 m.

Go 9b- dark-grey marls with ammonites and belemnites. 0.25 m.

Go 9c- grey marls, intensely bioturbated, with phosphatic nodules, belemnites and ammonites. 1.00 m.

Go 10a- grey marls, intensely bioturbated, with phosphatic nodules, belemnites and ammonites. 1.50 m.

Go 10b- nodular argillaceous limestones with ammonites. 0.15 m.

Go 10c- bioturbated grey marls being dark-grey in the middle part with ammonites, belemnites and

phosphatic nodules. Within the last 20 cm, a white argillaceous millstone level is visible. 0.85 m.

Go 11- alternation of black shales and dark-grey calcareous clays with ammonites, belemnites, rare

bivalves and pyritic nodules. Toward the top, the clays appear lighter in colour: grey to brownish with

some yellowish level due to alteration of pyritic layer (jarosite ?). This unit is subdivided into 14

decimetric black shale/calcareous clays doublets. 6.10 m.

Virgatus Zone ROUILLIER (1845).

Ammonite fauna, after MESEZHNIKOV et al. (1984) and MlTTA (1993): Virgatites virgatus (Buch),

Virgatites cf. sosia (Vischniakoff), Virgatites pallasianus (d'Orb.), Virgatites pusillus (Mich.),

Virgatites gerassimovi Mitta, Lomonossovella lomonossovi (Vischniakoff), Acuticostites acuticostatus

(Michalski), Acuticostites bitrifurcatus Mitta.

Go 12- conglomerate of red to black phosphatic nodules and pebbles, belemnites and ammonites:

Virgatites virgatus (Buch). 0.10 m.

Go 13- yellowish to greenish argillaceous silts with dispersed phosphatic pebbles and belemnites. 14 cm

below the top, phosphatic pebbles, belemnites and vertebrate remains (Icthyosaurus, Pleisiosaurus) are

concentrated. 0.50 m.

Go 14- conglomerate of black phosphatic pebbles, belemnites and ammonites ( Virgatites virgatus

(Buch)) in a sandy matrix. The top of this unit has an irregular surface. 0.10 m.

Nikitini Zone LAHUSEN (1883).

Ammonite fauna, after Mitta (1993): Epivirgatites nikitini (Michalsky), Epivirgatites bipliciformis

(Nikitin), Laugeites stschurowskii (Nikitin), Laugeites aenivanovi Mitta, Lomonossovella lomonossovi

(Vischniakoff).

PIERRE HANTZPERGUE ET AL.

Go 15- yellowish to greenish argillaceous sands passing laterally to sandstones with ammonites,

Paracraspedites sp.. Epivirgatites nikitini (Michalsky), bivalves ( Buchia sp.) and concentration of

belemnites to the top. The upper limit is an undulated oxidised surface with a rust-colour. 0.60 m.

Upper Volgian: Kashpir section (Ka)

Fulgens Zone NIKITIN (1888).

Ammonite fauna, after Gerasimov (1969): Kashpurites fulgens (Trautschold), Kashpurites subfulgens

(Nikitin), Garniericeras catenulatum (Fischer), Craspedites okensis (d'Orb.), Craspedites nekrassovi

Prigorovski.

Ka 13- brownish to greyish clayey sandstones with calcareous seams containing ammonites,

Kashpurites fulgens (Trautschold), Garniericeras catenulatum (Fischer), belemnites ( Acrotheutis

mosquensis) and bivalves (Buchia sp.). At the top of the unit occurs a thin level (2 cm) of strongly

ferrugineous carbonate. 0.50 m.

Subditus Zone NIKITIN (1888).

Ammonite fauna after MESEZHNIKOV et al. (1984): Craspedites okensis (d'Orb.), Craspedites subditus

(Trautsch.), Craspedites subdivides (Nikitin), Garniericeras catenulatum (Fischer).

Ka 14a- light-grey fine-grained glauconitic sandstones with belemnites, ammonites and bivalves.

0.25 m.

Ka 14b- light-grey sands poorly cemented with calcareous patches. This unit is rich in ammonites,

Craspedites okensis (d’Orb.), Craspedites subditus (Trautsch.), broken belemnites and Buchia sp.

0.60 m.

Ka 15- light-grey fine-grained sandstone with calcareous cement containing ammonites and Buchia sp.

0.35 m.

Ka 16- dark-grey bioturbated sandstones with numerous ammonites and bivalves. 0.30 m.

Nodiger Zone NIKITIN (1888).

Ammonite fauna, after GERASIMOV (1969): Craspedites nodiger (Eichwald), Craspedites kaschpuricus

(Trautsch.), Craspedites parakaschpuricus Gerassimov, Craspedites milkovensis Stremooukhov,

Craspedites kuznetzovi (Sokolov). Craspedites mosquensis Gerassimov, Garniericeras subclypeiforme

(Milaschevitsch).

Ka 17a- light-grey fine-grained sandstones, strongly bioturbated. with dark-grey burrows, ammonites,

Craspedites nodiger (Eichwald) and belemnites. 0.35 m.

Ka 17b- fine-grained calcareous sandstones starting by a level containing cm-long phosphatic pebbles

and ammonites. 0.20 m.

Ka 17c- light-grey calcareous sandstones with lumachellic lenses rich in belemnites, ammonites and

bivalves. 0.30 m.

Ka 18- massive light-grey fine-grained calcareous sandstones, strongly bioturbated, with numerous and

non-oriented shells, belemnites and ammonites. 1.10 m.

Ka 19- light-grey to greenish bioclastic sandstones having a nodular appearance. Numerous ammonites:

Craspedites nodiger (Eichwald), Craspedites kaschpuricus (Trautsch.), Garniericeras subclypeiforme

(Milaschevitsch). 0.40 m.

Ka 20- brown finely laminated black shale overlain by Ryazanian deposits. 0.15 m.

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

AMMONITES ZONATION AND CORRELATIONS

OXFORDIAN

On the central part of the Russian Platform (middle Volga basin), the Oxfordian stage is

characterized by boreal Cardioceratids. This ammonite faunas allow a precise correlation with the

standard zonation of the boreal Oxfordian (SYKES & SURLYK, 1976) and with the Amoeboceras

zonation of the boreal upper Oxfordian (SYKES & CALLOMON, 1979).

The equivalence between sub-boreal and tethyan zonations is yet imperfect: the base of Cordatum

Zone is only correlated with the Claromontanus Zone of the tethyan scheme (CARIOU et al.. 1997).

In the excellent sections of Makariev, on the Unzha River (Nikitin, 1884), the Oxfordian shows

likely a hiatus of the lower part. The first Oxfordian ammonite faunas is a Cardioceratid assemblage,

including Cardioceras gr. cordatum (Sow.), typical form of the standard Cordatum Subzone (Cordatum

Zone). Although the species ranges are not precisely determined, it seems that Bukowskii and/or

Gloriosum Subzones, and Costicardia and/or Percaelatum Subzones are included in the basal Oxfordian

gap-

The middle Oxfordian Cardiocerartid faunas, dominated in lower part by C. (Subvertebriceras)

densiplicatum Boden. C. (Plasmatoceras) popilaniense Boden, C. (Subvertebriceras) zenaidae Ilov. and

C. (Plasmatoceras) tenuistriatum Borissiak, indicate the Densiplicatum Zone. The occurrence of C.

(Cawtoniceras) tenuiserratum (Opp.) and P. (Arisphinctes) gr. plicatilis (Sow.) in upper part of Mk 15

level, suggest the Tenuiserratum Zone. A Tenuiseratum Horizon was defined at the top of the

Antecedens Subzone (Plicatilis Zone) of the submediterranean province (CARIOU, 1966; MALINOWSKA,

1966). This unit allows a precise correlation between the top of the boreal middle Oxfordian and the

medium part of this substage in Tethyan realm (CARIOU et ai, 1997; MESEZHNIKOV, 1988, 1989).

In the upper Oxfordian boreal series, an Amoeboceras faunal sequence allows to subdivide this part

of the Stage into four zones: Glosense, Serratum, Regulare and Rosenkrantzi Zones (SYKES & SURLY K,

1976). In Makariev sections, the Glosense Zone contains a typical fauna of the Ilovaiskii Subzone. The

upper Glosense Subzone is not clearly identified. These boreal unit is approximately equivalent to the

lower part of the Submediterranean Bifurcatus Zone (Stenocycloides Subzone, CARIOU et ai, 1997).

The assemblage of Amoeboceras ilovaiskii (Sok.) and A. cf. glosense (Bigot & Brasil) (Mk 12) possibly

indicates the nearby of the Ilovaiskii/Glosense boundary. A hiatus ot the Glosense Subzone seems

probable.

The Koldeweyense and Serratum Subzones (Serratum Zone) are indicated by the occurrence of their

index. The assemblage of different Amoeboceras with A. leucum Spath and A. tuberculatoalternans

(Nik.) indicate the upper Oxfordian Regulare and Rosenkrantzi Zones. It should be noted that the

ammonite ranges in this section need to be worked out more precisely. The occurrence ot Ringsteadia

cuneata (Trautsch.) (MESEZHNIKOV, 1988) and R. frequens Saif, in Mk 8d level indicates the uppermost

Oxfordian. This Ringsteadia fauna is directly followed by Kimmeridgian Pictoma (Mk 8c).

Consequently, the Oxfordian/Kimmeridgian boundary can be precisely correlated between Russian

Platform and sub-boreal western-european series.

Concerning a possible correlation with tethyan series, an equivalence is suggested between boreal

Serratum and Regulare Zones and the tethyan Biturcarus Zone (CARIOU et al., 1997). The

correspondence of the Oxfordian/Kimmeridgian boundary for this two realms is still imprecise. Recent

propositions (ATROPS et al., 1993) suggest that the usual tethyan Planula Zone belongs partly or totally

into the Kimmeridgian stage.

PIERRE HANTZPERGUE ETAL.

KIMMERIDGIAN

During the Kimmeridgian, the ammonites provincialism is more pronouneed in the north tethyan

margin. The Tethyan and Boreal Realms are separated by an intermediate area: the Franco-German

Bioma (Hantzpergue, 1979, 1989 ; HANTZPERGUE et al„ 1997 ; Enay, 1966, 1980; Haug, 1898).

The subboreal province is characterized by Cardioceratids and Aulacostephanids with respectively the

genus Amoeboceras and Pictonia , Rasenia, Aulacostephanus. In an other hand, the Franco-German

Bioma is an overlapping area for the sub-boreal and tethyan faunas but above all, a differentiated area

with endemic forms of Aspidoceratids, Aulacostephanids and Perisphinctids (HANTZPERGUE, 1989).

The middle Volga Kimmeridgian series show the same particularities and the best biostratigraphical

correlations can be made with the Kimmeridgian stage.

The lowermost Russian usual zone, the Evoluta Zone (MESEZHNIKOV, 1988) contains a Pictonia

fauna. The Densicostata and Baylei Horizons located in Mk 8c-8b levels of Makariev section define the

standard Baylei Zone.

The "kitchini beds" (MESEZHNIKOV, 1988) are characterized by Amoeboceras faunas with A.

(Amoebites) kitchini (Saif.) and A. (Amoebites) cricki (Saif.). Rasenia gr. cymodoce (d’Orb.) and

Rasenia gr. uralensis (d'Orb.) occur in Mk 7a-6a levels of the Makariev section. They indicate a

Cymodoce Horizon located at the lower part of the Cymodoce Subzone (HANTZPERGUE et al„ 1997),

and the "Zonovia" uralensis Subzone corresponds probably with the upper part of the standard

Cymodoce Zone. Consequently, the classic "Amoeboceras kitchini Beds” of the Russian Platform are

equivalent or partially equivalent to Baylei and Cymodoce Zones of the western european standard

biostratigraphical scale.

The lower Kimmeridgian of middle Volga area is not complete: Makariev and Mimei village

outcrops are relatively poor in ammonite faunas and incomplete for the middle and upper part of

Cymodoce Zone.

Upper Kimmeridgian is most fully developed on these area, but lower Mutabilis Zone, (equivalent to

the Sosvaensis Zone (MESEZHNIKOV, 1988) or to the Acanthicum Zone auct .), is no more visible.

Orthaspidoceras liparum (Opp.) is mentioned by Meseznikov below the lake level of the Kuyibishev

reservoir. This ammonite is the dimorphic form of O. lallierianum (d’Orb.), index of a Lallierianum

Horizon and a Lallierianum Subzone, located at the upper part of the standard Mutabilis Zone

(Hantzpergue, 1989).

In compensation, the Eudoxus and Autissiodorensis Zones show the most biostratigraphical

accuracy. Three western european horizons of the Eudoxus Zone are present in the Dubky section:

— Caletanum Horizon, Caletanum Subzone (HANTZPERGUE, 1979), with Aspidoceras caletanum

(Opp.), Aspidoceras gr. longispinum (Sow.), Aulacostephanus eudoxus (d’Orb.), Pararasenia cf.

hybridus Ziegler and Amoeboceras sp.. levels Ko 1-3, Du 1;

— Contejeani Horizon, Contejeani Subzone (HANTZPERGUE, 1979), with Aspidoceras gr. quercynum

Hantzpergue, Aulacostephanus contejeani (Thurmann), Tolvericeras sevogodense (Contini &

Hantzpergue), Du 2 level;

Yo Horizon, Contejeani Subzone, with Aulacostephanus yo (d'Orb.), Aspidoceras gr. quercynum

Hantzpergue, Aspidoceras sp. and Tolvericeras gr. sevogodense (Contini & Hantzpergue), levels Du 3-

6 .

The Autissiodorensis Zone corresponds to the occurrence of the index Aulacostephanus

autissiodorensis (Cott.) and its dimorphs, A. volgensis (Vischn.),A. kirghisensis (d'Orb.), A. undore

(Pavl.). In the upper part, was defined the Fallax Subzone (MIKHAILOV, 1962 b) with dominant

Virgataxioceras fallax (Ilov.) constantly accompanied by the zonal index. The Kimmeridgian/Volgian

boundary is setting at the last apparition datum of A. autissiodorensis (Cott.).

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

VOLGIAN

The deposits of the “Volgian stage” of the typical region (central part of the Russian Platform) are

subdivided into three substages (Mikhailov, 1962 a, 1964, Gerasimov & Mikhailov, 1966): lower

Volgian, (SOKOLOV, 1901, “Wetlianian” horizon), middle Volgian (NIKITIN, 1881 a, “lower Volgian

stage”), and upper Volgian (Nikitin, 1881 b, "upper Volgian stage”).

Traditionally, the Volgian crowned the Jurassic system and was considered to an equivalent of the

Tithonian stage. However, many data, in several areas of the world, contradict the correlation adopted in

Russia (Sey & Kalacheva, 1993). A recent resolution of standing commission of the

Interdepartmental Stratigraphic Committee of Russia (ISC) on the Jurassic and Cretaceous systems

(1996, unpublished) proposed to draw the Jurassic/Cretaceous boundary in the Boreal realm between the

middle and upper substage of the Volgian (Nikitini/Fulgens Zones). In that way, the upper Volgian is

correlated with two lower zones of the Berriasian stage. In the subboreal province, such a break

corresponds to the boundary between marine series with ammonites of the Dorset Portland Beds and

lagoonal-lacustrine facies of the Purbeck Beds. The top of Portlandian sensu anglico is putting above the

Oppressus Zone (BlRKELUND, et al., 1984) and the Portlandian last zones (Primitivus, Preplicomphalus

and Lamplughi Zones) can be an equivalent to the upper Volgian.

At the All-Russian Conference in Saint Petersbourg in 1988 (Resolution. 1993), on the development

of an unified stratigraphic scheme of the Mesozoic deposits of the Russian Platform, the Volgian stage

was subdivided into the following substages, zones and subzones: lower substage (Klimovi Zone,

Sokolovi Zone, Pseudoscythica Zone), middle substage (Panderi Zone with Pavlovi and Zarajskensis

Subzones, Virgatus Zone with Gerassimovi, Virgatus and Rosanovi Subzones, Nikitini Zone with Blakei

and Nikitini Subzones, Oppressus Zone), and upper substage (Fulgens Zone, Subditus Zone, Nodiger

Zone with Mosquensis and Nodiger Subzones).

Today Volgian is differently subdivided (MESEZHNIKOV, 1982; MlTTA, 1993 ; GERASIMOV et al.,

1995):

— Klimovi Zone MICHAILOV (1962 a): Ilowaiskya klimovi Ilovaisky, Neochetoceras aff. steraspis

(Opp.), Glochiceras sp., Gravesia cf. gigas (d'Orb.), Sutneria aff. subeumela (Schneid).

— Sokolovi Zone ILOVAISKY & FLORENSKY (1941): Ilowaiskya sokolovi Ilovaisky, I. pavida

Ilovaisky, Haploceras aff. elimatum (Opp.), Glochiceras aff. lithographicum (Opp.), Glochiceras aff.

parcevali (Font.).

— Pseudoscythica Zone ILOVAISKY & FLORENSKY (1941): Ilowaiskya schaschkovae Ilovaisky, /.

pseudoscythica Ilovaisky, Pectinatites aff. pectinatus (Phillips), P. ianschini (Ilovaisky), P.

tenuicostatus Mikhailov, Weatleyites aff. aestlecottensis (Salteld), W. arkelli Michailov, W. spathi

Mikhailov, Physodoceras neuhurgense (Oppel).

— Panderi Zone ROZANOV (1906): Zaraiskites zarajskensis (Michalski), Z. scythicus (Vischniakoff),

Z. michalskii Mitta, Z. quenstedti (Rouillier & Fahrenkohl), Z. tschernyschovi (Michalski ). Acaticostites

acuticostatus (Michalski), A. bitrifurcatus Mitta, Dorsoplanites dorsoplanus (Vischniakoif),

Dorsoplanitespanderi (d'Orbigny), Pavlovia pavlovi (Michalski).

Subdivision of Panderi Zone into two Subzones is impossible. The same ammonite species occur in

lower and upper parts of zone; there are not biostratigraphicaly or lithostratigraphicaly limited.

Mikhailov (1962 a) who proposed the subdivision of the Panderi Zone into two subzones, as

Ilovaisky (Ilovaisky & Florensky, 1941) which proposed such subdivision, have based his

suppositions on Rozanov's indications. He was the first, who believed in the compound composition

Panderi Zone. However, ILOVAISKY & MIKHAILOV did not take into account that the greater part ot

Rozanov's “lower Subzone Panderi-Zone” was included by the latest workers into the lower Volgian

“Wetlianian horizon”.

Virgatus Zone ROUILLIER (1845) (emend, by LAHUSEN, 1883 and ROSANOV, 1906): Virgatites

virgatus (Buch), V. sosia (Vischniakoff), V. pusillus (Michalski), V. pallasianus (d'Orb.), V. larisae

PIERRE HANTZPERGUE ETAL.

Mitta, V. gerassimovi Mitta, V. rosanovi Michailov, V. crassicostatus Mitta, Dorsoplanites serus

Gerasimov, D. rosanovi Gerasimov, Serbarinovella serbarinovi Mitta, S. ringsteadiaeformis

(Gerasimov), Lomonossovella lomonossovi (Vischniakoff), Craspedites ivanovi Gerasimov, C.

pseudofragilis Gerasimov, Acuticostites acuticostatus (Michalski), Laugeites stschurowskii (Nikitin),

Crendonites kuncevi Michailov.

The subdivision ot the Virgatus Zone is based on the species and succession of the genus Virgatites

and Dorsoplanites:

— Gerassimovi Subzone ROZANOV (1919) Virgatites gerassimovi Mitta, V. pusillus (Michalski), V.

pallasianus (d'Orb.), V. sosia (Vischniakoff). Dorsoplanites serus Gerasimov, D. rosanovi Gerasimov,

Lomonossovella lomonossovi (Vischniakoff), Acuticostites acuticostatus (Michalski).

— Virgatus Subzone ROUILLIER (1845) (emend, by ROSANOV, 1919): Virgatites virgatus (Buch), V.

pallasianus (d'Orbigny), V. sosia Vischniakoff, V. larisae Mitta, V. crassicostatus Mitta., Dorsoplanites

serus Gerasimov, D. rosanovi Gerasimov, Lomonossovella lomonossovi (Vischniakoff), Serbarinovella

serbarinovi Mitta. S. ringsteadiaeformis (Gerasimov), Craspedites ivanovi Gerasimov, C. pseudofragilis

Gerasimov.

Rosanovi Subzone ROZANOV (1913) (= Ivanovi Subzone): Virgatites virgatus (Buch), V. rosanovi

Michailov, V. pallasianus (dOrbigny), V. sosia (Vischniakoff). Dorsoplanites serus Gerasimov, D.

rosanovi Gerasimov, Lomonossovella lomonossovi (Vischniakoff), Craspedites ivanovi Gerasimov, C.

pseudofragilis Gerasimov, Crendonites kuncevi Michailov, Laugeites stschurowskii (Nikitin).

— Nikitini Zone LAHUSEN (1883): Epivirgatites nikitini (Michalski), E. bipliciformis (Nikitin), E.

lahuseni (Nikitin) Laugeites stschurowskii (Nikitin), L. aenivanovi Mitta, Lomonossovella lomonossovi

(Vischniakoff), Craspedites ivanovi Gerasimov, Craspedites pseudofragilis Gerasimov.

The separation of the upper part of formerly Nikitini Zone as Oppressus Zone by CASEY &

Mesezhnikov (1986) cannot be adopted. Nikitini Zone is the interval of distribution of Epivirgatites

nikitini (Michalski). which is found in complete section of zone in its formerly volume. The separation

ot ”the beds with Paracraspedites oppressus ”, as upper subzone of Nikitini Zone, is also impossible.

The presence of the western-european genus Paracraspedites is not confirmed in middle Volgian.

The separation ol the lower part Nikitini Zone into Blakei Subzone cannot be also adopted The name

Lomonossovella blakei (Pavlow) emend. MIKHAILOV is the younger synonym of L. lomonossovi

(Vischniakoff). There are no data which allow to distinguish the complexes of “Blakei and Nikitini

Subzones . The differences shown by Casey & Mesezhnikov (1986) had geographical nature. They

cannot be adopted as evidence of more older Nikitini Zone age in near-Moscow and upper Volga than

the age of the beds in middle Volgian.

Fulgens Zone Nikitin (1888): Craspedites fragilis (Trautschold), C. okensis (d'Orb.), C. nekrassovi

rigorovsky, C. knlovi Prigorovsky, C. subditoides (Nikitin), Garniericeras catenulatum (Fischer) G

mterjectum (Nikitin), Kachpurites fulgens (Trautschold), K. subfulgens (Nikitin).

Subditus Zone NIKITIN (1888): Craspedites okensis (d'Orb.), C. nekrassovi Prigorovsky, C. jugensis

rigorovsky, C. subditus (Trautschold), C. subditoides (Nikitin), Garniericeras catenulatum (Fischer)

G. interjectum (Nikitin).

Nodiger Zone NIKITIN (1888): Craspedites nodiger (Eichwald), C. triptychus (Nikitin) C.

kaschpuricus (Trautschold), C. parakaschpuricus Gerasimov, C. milkovensis Strmooukhov' C

kuznetzovi (Sokolov), C. mosquensis Gerasimov, Garniericeras subclypeforme (Milaschevitsch).

The Nodiger Zone admits two subdivisions: Subzone of Craspedites mosquensis (lower) and

Subzone ol Craspedites nodiger (upper). These subzones differ by the distribution of species

Craspedites mosquensis Gerasimov and C. triptychus (Nikitin) in the lower part (subzone) of Nodiger

The correlations ol the base of the lower Volgian with the Kimmeridgian/Tithonian boundary of

western-hurope area could be assured, on the basis of genus Gravesia found in the Klimovi Zone on the

Gorod.sche lectostratotyp.cal section (MESEZHNIKOV, 1988). On a same way, Neochetoceras and

Glochiceras mentioned by Gerasimov & Mikhailov (1966), could be a possible equivalent with the

lowermost Tithoman (Hybonotum Zone).

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

The correlation of the base of the middle Volgian (Panderi Zone) is much less certain. The pavlovids

of the Panderi Zone, suggest a rough parallel with the Pallasioides/Rotunda boundary in Britain

(CALLOMON & BlRKELUND, 1982).

Higher in the succession, the group of Epivirgatites nikitini (MlCHALSKI, 1890). has been equated

with the Albani-Glaucolithus Zones of the English Portlandian (WIMBLEDON & COPE, 1978).

“ Lomonossovella” lomonossovi (Vishniakov, 1882) appears to be a true Kerberites Buckmann from the

Kerberus Zone (CALLOMON & BlRKELUND, 1982). The upper Volgian begins everywhere with the

appearance of Craspedites. The closest correspondence which can suggest is between the Nodiger Zone

and the English Preplicomphalus Zone, in which the Craspedites has also been found (CASEY, 1973,

CALLOMON & BlRKELUND, 1982).

STRATIGRAPH1CAL DISTRIBUTION OF RUSSIAN PLATFORM

"OIL SHALE BANDS" AND THEIR GEOCHEMICAL TRENDS

The background facies of the Upper Jurassic deposits from the Russian Platform are mainly

mudstone and marlstone with CaCO, content lower than 40% (25% in average). Carbonate-free

sandstone and siltstone, as subordinate facies, are mainly related to upper Volgian deposits. Some

samples show higher carbonate content (50-80%), and correspond either to sandstone with calcitic

cement or carbonate-nodules within the mudstone. The background facies show a very variable Corg.

content, from about 1 wt% (higher than the average for shales) to very high values (10 wt%), that are

elevated compared to recent and ancient marine sediments. Some levels show higher Corg. (up to 50%)

and correspond to finely laminated shales, here called oil shales (Fig. 6). Such a richness is exceptional

and the corresponding sediment could be regarded as pure organic matter.

Middle Oxfordian

•. , Ihicknoss 1.7 m

0 1 3 .*> 10 30 ‘jO 0 JO 40 60 80 100

Lower Oxlordlan

thickness 1.3 m

0 1 3 10 30 SO 0 20 40 60 00 100

TOC (wt %) CaC0 3 (w1 %)

Upper Volgian

thickness >5 m

TOC {v»1 %) CaC0 3 l«t %)

Fig. 6.— Frequency distribution for

TOC and CaCO, content of

samples from the Upper

Jurassic of the Russian

Platform. Samples with larges

wood fragments are here

disregarded (Note change in

TOC scale axis for values

above 5 and 10 % TOC).

Fig. 6.— Histogrammes des

frequences du contenti en COT

et CaCO , des echantillons du

Jurassique superieur de la

plate-forme russe. Les

echantillons contenant de

grands fragments de bois sont

ici negliges. (Noter le

changement d'echelle des

abscisses pour les valeurs an

dessus de 5 et 10% de COT).

PIERRE HANTZPERGUE ETAL.

The pyrolytic measurements show that the organic matter is widely distributed between type 11

(marine) and type IV (altered organic matter), according to the broad distribution of hydrogen index (HI)

values, ranging from 10 to 700 mg HC/g TOC (Fig. 7). Oil shales show the higher HI values and are

related to type II organic matter. Nevertheless, such facies may likewise contain organic matter with HI

values less than 150. Most of the mudstone and marlstone show likewise low to medium HI values (23

to 250). These low values, associated with low organic carbon content, support the hypothesis of strong

alteration of the organic matter. Hl-values in organic-lean sediments, however, can be due to mineral

matrix effect, e.g. adsorption of pyrolytically generated hydrocarbons on clay mineral surfaces

(Espitalie et al., 1985-86). Detailed organic geochemical studies are in progress in order to carefully

determined the type of organic matter and to characterized the depositional environment by the mean of

biomarkers.

Fig. 7.— Hydrogen index vs Tmax diagram of

selected samples from ihe Upper Jurassic of

the Russian Platform.

F/c. 7.— Diagramme Index d’hydrogene vs. Tmax

d’echantillons selectionnes dans le Jurassique

superieur de hi plate-forme russe.

Petroleum potentials of the oil shales are very good with an average of 95 kg HC/t of rock and some

exceptional potentials ranging from 200 to 300 kg/t for the Volgian oil shale bands.

six hmtd’s 1 ^^ythrough the studied interval and are mostly concentrated in

stradgr^hicforder^Fig^ 8)f baCkgr ° Und mudst ° ne and "histone with less Corg. content. They are by

ba n d ' cl , ose t0 the mi ddle-upper Oxfordian boundary (Glosense Zone) in

the Makariev section (level Mk 14). Its organic content varies from 1 1 to 19% TOC. This level is

overlain by 15 cm of dark claystones with bioturbations (level Mk 13), containing up to 6.5% TOC A

we itownm s ?hsS 011 S f hale le M el eXiStS bdow this first horizo "- ™s first oil shale band is

■ . " , subsurface as far as Moscow, where its thickness increases up to 1 m, whereas its organic

richness is decreasing (only 3% Corg, according to authors unpublished measurements);

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

— a lower Kimmeridgian (Cymodoce Zone) oil shale band is described here for the first time in the

Russian Platform. This level is 50 cm thick in the Mimei village section (level Ta 5) and its organic

richness is 15% TOC;

— the most famous and widespread oil shale band is of middle Volgian age and is more precisely

related to the Panderi Zone. This band was investigated in detail along the 6 m-thick profile of

Gorodische (level Go 11). It is made by alternation of black shales and dark claystones. The organic

richness of black shales varies from 2.3 to 44.5% TOC with a 16.5% mean value. The dark claystones

contain between 0.5 and 5.4% TOC;

— the next band belongs to the same Substage but has a Virgatus Zone dating. This level was not

recognised along the Gorodische section because of the predominance of sandy facies;

— the fifth band, from the base of upper Volgian (Fulgens Zone), was not recognised along the

Gorodishche or Kashpir sections because of the predominance of sandy and calcareous-sandy facies;

— the last band belongs to the uppermost Volgian (Nodiger Zone), equivalent to the lower

Berriasian. This level has a thickness ranging between 6 to 15 cm in the Kasphir section (level Ka 20)

and an organic richness fluctuating from 22 to 33% TOC.

Fig. 8.— Stratigraphical distribution of

the oil shale band (OSB) in

both England and Volga

basins. Time scale according

to Odin & Odin (1990). See

text for explanation.

Fig. 8 .— Distribution temporelle des

bandes de schistes bitumineux

(OSB) en Angleterre et dans le

bassin de la Volga. Echelle des

temps d'apres Odin <6 Odin

(I 99G). Voir le texte pour les

explications.

Source:

PIERRE HANTZPERGUE ETAL.

It should be noted that the upper Kimmeridgian deposits were not completely investigated during our

field work and the Mutabilis Zone and basal part of the Eudoxus Zone was not recognised.

COMPARISON WITH THE KIMMERIDGE CLAY FORMATION

Late Jurassic is known to have been prone to the deposition of Corg.-rich series at a global scale and

especially in the boreal domain (North, 1979; ULMISHEK & KLEMME, 1990; Baudin, 1995). The

Kimmeridge Clay Formation is one of the famous petroleum source rock which was deposited during

this time interval. It extends onshore from the Wessex basin in southern England to the Cleveland basin

of northern Yorkshire and is the main source rock in the North Sea basin. It has an homogeneous dark-

coloured mudstone facies with a few, apparently isochronous, carbonate and oil-shale marker-beds that

can be correlated all over the basin (Cox & Gallois, 1981).

Because the age of the Kimmeridge Clay Formation ranges from Kimmeridgian to Volgian, that

includes a large part of the studied interval on the Volga basin, we attempt to compare the stratigraphic

distribution of oil shales between these two provinces.

According to the works of GALLOIS (1978), COX & GALLOIS (1981), WlGNALL (1991), HERBIN et

al. (1991), HERBIN & Geyssant (1993) and Ramdani (1996) five oil shale bands can be recognized in

the Kimmeridge Clay Formation (Fig. 8):

— a middle Eudoxus band (BGS bed 29 sensu GALLOIS, 1979);

— an upper Eudoxus-lower Autissiodorensis band (BGS beds 32 and 33);

— an Elegans-basal Scitulus band (BGS beds 36 and 37);

— an upper Wheatleyensis-basal Hudlestoni band (BGS beds 42 and 43);

— an uppermost Hudlestoni-Pectinatus band (beds 45-47 sensu WlGNALL, 1991);

Although the frequency of oil shale bands is greater in the middle part of the Formation (Eudoxus to

Pectinatus Zones), some oil shales are present in the Mutabilis and Pallasioides Zones (Fig. 8). The

Mutabilis oil shale band is demonstrated by Herbin et al. (1991) in the Yorkshire, whereas the

Pallasioides band corresponds in the Dorset to beds 52-54 (Wignall, 1991).

It appears that the stratigraphic distribution of the oil shale bands from the Kimmeridge Clay

Formation is completely different from those of the Volga basin (Fig. 8). As might be expected, the

probably shallower environment in the Volga basin did not allow the preservation of organic matter

during these time intervals. It appears that either these intervals were not associated with a relative

change in water depth sufficient to allow dysoxic-anoxic conditions to be established or that other

watermass factors were not suitable to organic matter preservation during the upper Kimmeridgian and

lower Volgian. On the contrary, oil shale bands are present on the Russian Platform during upper

Oxfordian, lower Kimmeridgian, middle and upper Volgian when the environments were more sandy

and shallower in England and unfavourable to the organic matter preservation.

This lack of temporal correlation of the organic-rich deposits at a large scale during the Upper

Jurassic has been mentioned previously for the Tethyan realm (BAUDIN, 1995). It seems that the Upper

Jurassic was a suitable period for organic matter preservation, but any stratigraphic interval can be

regarded as global time-slice prolific for source rock deposition. The oil shale bands discussed here are

definitely not equivalent to oceanic anoxic events as the lower Toarcian (JENKYNS 1988) or

Cenomaman-Turoman (BUSSON & CORNEE, 1996) events

CONCLUSION

The above biostratigraphic study of the Upper Jurassic from middle

Russian series to be correlated more precisely with the western-european

the Oxfordian Stage, the use of Cardioceratids faunas authorised some

Volgian basin has enabled the

standard zonation. Concerning

equivalencies with boreal and

Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

sub-boreal successions. The Oxfordian/Kimmeridgian boundary is precisely identified with the basal

Kimmeridgian Densicostata Horizon.

The best biostratigraphical correlations between the Russian Platform and western Europe are

achieved for the Kimmeridgian stage. Seven ammonites horizons are common within these two areas: P.

densicostata, P. baylei, O. lallierianum, A. caletanum, A. contejeani, A. yo and A. autissiodorensis.

Morever, the levels with R. uralensis can be probably subdivided with various Rasenia species.

Similarly, the “Acanthicum Zone auct" seats many suboreal Aulacostephanids and a more precise

biostratigraphical scheme can be obtain with better correlations between Russian Platform and the

subboreal province (North Sea basin, southern England, Aquitaine and Paris basins, northern

Germany...).

On the other hand, the equivalences between the regional “Volgian stage" and/or

Tithonian/Portlandian sensu anglico , are much less certain. Some difficulties proceeded of a pronounced

faunal provincialism. Correspondences can be only suggested by affinities of the endemic Russian

ammonites and the boreal faunas. Local scheme is still necessary.

Geochemical characterisation of the Upper Jurassic series from the Russian Platform show several

intervals with high organic content (Corg >10%) and good petroleum potentials. Nevertheless, they are

not synchronous with organic-rich intervals from the Kimmeridge Clay Formation. Further studies are

needed to understand the depositional control of these oil shales at a small scale, but the present data

clearly indicate that oil shale bands cannot be taken as marker beds at a large scale.

ACKNOWLEDGMENTS

We are indebted to the Peri-Tethys Program for providing financial support for this study (prop. 95-

28 and 95/96-28). We grateful acknowledge J. SANFOURCHE for his helpful technical assistance tor

geochemical analyses. We are indebted to A.Y. Hue and J. THIERRY for their critical suggestions on an

earlier draft of this paper.

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Jurassic system. Izvestiya Akademiy Nauk SSSR, Seriya Geologicheskaya, 2: 118-138 fin Russian).

Gerasimov. P.A.. Mitta, V.V. & Kochanova. M.D.. 1995.— Volgian Fossils of the Central Russia. VNIGNI. Moscow:

1-116 (in Russian).

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Hantzpergue, P., 1979.— Biostratigraphie du Jurassique .superieur

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Hantzpergue, P., Atrops, F. & Enay, R„ 1997.— Kimmeridgien. In: E. Cariou & P. Hantzpergue (eds), Biostratigraphie

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Hf.rbn. JP.. Mull®. C. Geyssant. JR.. Meliires, F. & Penn. IE.. 1991.— HJierogeneite quantitative et qualitative de la

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stratigraphiq nt.Revue de l ’Institut frangais du Petiole, 46. 6:675-712.

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Source: MNHN, Paris

UPPER JURASSIC OF THE VOLGA BASIN

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The Mesozoic of the Mangyshlak (West Kazakhstan)

Maurizio GAETANI Marco BAUNI Valery J. VUKS m ,

Vera A. GAVRILOVA Eduardo GARZANTI 11 ', Alda NlCORA

Elisabetta Erba % Elie CARIOU < 3> , Fabrizio Cecca ,4 \

Isabella P REMO LI SlLVA Maria Rose PETRIZZO

Simonetta Cirilli 151 & Raffaella BucefaloPalliani

01 Dipartimento di Scienze della Terra, Via Mangiagalli 34, 20133 Milano, Italia

121 VSEGE1, Sredny pr. 74. Saint-Petersburg 199106. Russia

1,1 Universite de Poitiers, UFR Sciences Fondamentales et Humaines, Laboratoire de Geobiologie,

Biochronologie et Paleontologie, 40, avenue du Recteur Pineau. F-86022 Poitiers, France

141 Istituto di Geologia, University di Urbino, loc. Crocicchia. Urbino, Italia

l5> University di Perugia, Dipartimento di Scienze della Terra, Piazza University 1, Perugia, Italia

ABSTRACT

The Mesozoic succession of the Mangyshlak (W. Kazakhstan) starts with the Lower Triasstc Birkut. Otpan. and Dolnapa

Formations, representing an alluvial plain, Permian units were not detected. The marine ingression is recorded by the lyururpa

Group, which yielded ammonoid/conodont faunas, dated to the Olenekian. Towards the top ol the Group, a resumption ot

terrigenous sedimentation and a shallowing-upward trend, is recorded. Sandstone petrography demonstrates fmt^gramed

litharenites or feldspathic litharenites, largely derived from "dacite" volcanics. Accumulation exceed 200-300 m/Ma. tne

overlying Karaduan Formation is dominated by continental facies, possibly of Middle Triassic age. It is overlaid by the C arman

Akmysh Formation, with re-establishment of marine conditions. Several high-frequency cycles are present, often with a strong

terrigenous input, which prevails upwards in the Shair Formation. The sandstone petrography indicates a persistent erosion ot a

volcanic arc. The 3000/4000 m-thick Triassic succession suggests a high sedimentation rate. The Mangyshlak area emerged and

was deformed during the Norian, due to the Eo-Cimmerian orogeny. Subaenal conditions persisted lor tens ol Ma, because

spectacular silcrete soils seal the Triassic beds. The generalized Jurassic transgression on an irregular topography occurred only

with the Middle Jurassic, with lacustrine, marshy or fluvial deposits. Marine ingressions occurred episodically during e

Middle Jurassic, becoming generalized during the early Callovian. Sedimentation continued with shales of Oxfordian age. t hey

ends with an ironstone, unconformably overlain by Berriasian oyster banks. The Jurassic is characterized by low subsi ence

rate, with mostly terrigenous sedimentation. The mid Jurassic sandstones are feldspathic litharenites, derived from low-gra e

metainorphics, granitoids and mafic to felsic volcanics. The Cretaceous succession is 800-1000 m- thick and is divider in o

Gaetani, M„ Balini. M..Vuks. V. J„ Gavrilova, V. A.. Garzanti. E.. Nicora, A.. Erba. E Cariou, E.. Cecca F.

Premoli Silva, I.. Petrizzo, M.R., Cirilli. S. & Buceealo Palliani. R.. 1998. — The Mesozoic of the Mangyshlak (West

Kazakhstan). In: S. Crasquin-Soleau & E. Barrier (eds), Peri-Tethys Memoir 4: epicratomc basins ot Peri-letnyan

platforms, Mem, Mus. natn. Hist, nat., 179 : 35-74. Paris ISBN : 2-85653-518-4.

Source: MNHN , Paris

MAURIZ10 GAETANI ETAL.

three parts. In the lower part, three to four thin sequences may be recognized. They are controlled by the Neo-Cimmerian

orogenic event, ending with a generalised emersion during the Barremian. The sandstones are lithic arkoses and feldspathic

litharenites, originating from igneous rocks and low-grade metamorphics. The subsidence rate greatly increased from the upper

Aptian up to the Turanian, and a clay to fine sandstone sequence was deposited, with phosphatic and ironstone horizons. W ith

the Coniacian, a white chalk unit sedimented over the whole area, ending in the Palaeocene.

RESUME

Le Mesozoi'que du Mangyshlak (Ouest Kazakhstan).

La serie mesozoi'que du Mangyshlak (ouest du Kazakhstan) debute avec les formations Birkut. Otpan et Dolnapa du Trias

inferieur, representant une plaine alluviale. Les unites permiennes n’ont pas ete detectees en surface. L'avancfe marine est

enregistrcc par le groupe Tyururpa, qui a livre des ammonites et des conodontes, dates de I Olenekien. La petrographie des gres

montre des litharenites a grains fins ou des litharenites feldspathiques largement derivees de roches volcaniques dacitiques.

L'accumulation depasse 200-300 nt/Ma. La formation Karaduan sus-jacente est dominee par des facies continentaux, peut-etre

du Trias rnoyen. Elle est surmontee par la Formation carnienne Akmysh, avec le retablissement des conditions marines.

Plusieurs cycles de haute frequence sont presents, souvent avec des apports terrigenes importants. qui dominent plus hault dans

la Formation Shair. La petrographic des gres indique Lerosion persistante d'un arc volcamque. La serie tnasique, epatsse de 3 a

4000 m, suggere un taux de sedimentation deve. La region du Mangyshlak a emerge et a ete deformee durant le Norien. sous

Peffet de l'orogenese Eo-Cimmerienne. Des conditions sub-aeriennes persistent durant des dizaines de Ma car des sols sihceux

spcctaculaires scellenl les depots du Trias. La transgression generalisee du Jurassique sur une topographic irteguhere se produit

seulement au Jurassique rnoyen avec des depots fluviaux, lacustres ou marecageux. Des incursions marines ont lieu

periodiquement durant le Jurassique rnoyen. devenant generalises durant le Callovien inferieur. La sedimentation se poursuit

avec les shales de l'Oxfordien. Ils se terminent avec un niveau riche en minerai de fer, recouverts en discordance par des bancs

a hultres berriasiens. Le Jurassique est caracterise par un faible taux de sedimentation essentiellement terrigene. Les gres du

Jurassique rnoyen sont des litharenites feldspathiques derivees de roches faiblement metamorphiques, de granitoides et de

roches volcaniques mafiques a acides. La serie cretacee est epaisse de 800 a 1000 m et est divisee en 3 parties. Dans la partie

inferieure, 3 a 4 sequences fines peuvent etre reconnues. Elies sont controlees par Levenement orogenique Neo-Cimmenen, et

s'achevent avec l’emersion generalisee durant le Bariemien. Les gres sont des arkoses lithiques et des litharenites

feldspathiques. issues de roches magmatiques et faiblement metamorphiques. Le taux de subsidence augmente fortement de

I'Aptien superieur jusqu’au Turonien, et on observe une sequence d'argiles ou de gres fins avec des horizons phosphates et

ferruaineux. Avec le Coniacien. une unite de craie blanche se depose sur fensemble de la region, se terminant au Paleocene.

INTRODUCTION

The Gorny Mangyshlak forms an alignment of hillocks on the east side of the Caspian Sea, reaching

an altitude of 560 m (Fig. 1). The Triassic to Palaeogene succession was studied extensively by Soviet

and Russian geologists, for its unique rock sequence exposed in isolated outcrops in the steppes of

Central Asia. Towards the end of the Triassic, rocks were fairly strongly folded and the overlying units

rest unconformably on them, folded in open asymmetric anticlines with a northward merging axial plane

and a partially faulted southern limb (POLL com. pers.). Consequently, the best outcrops and sections are

preserved along the northern limb.

The aim of the present paper is to summarize the main features of the Mesozoic succession, focusing

on the Triassic and Jurassic, with special attention to sandstone petrography, to the Lower Triassic

ammonoid succession and to sequence stratigraphy interpretation. Field work was carried out in August-

September 1995, during an expedition organised by N. Lyberis, UPMC, Paris and H. Yusufhocaev,

Technical University of Tashkent. M. Gaetani, M. Balini. V.A. Gavrilova, and V.J. Vuks worked in the

field, assisted by N. Lyberis. J.T. Poli (UPMC) and V.I. Troitzky (University of Tashkent).

THE TRIASSIC

The Triassic succession forms the core of the Mangyshlak anticlinorium, and crops out from west to

east in three main areas: the Karatauchik, West Karatau and East Karatau (Fig. 1). Most field work was

done in Karatauchik and West Karatau.

A basic lithostratigraphic scheme was proposed during the Samarkand Conference in 1971

(published in 1977 by the Interdepartimental Stratigraphic Commission, here called Samarkand Scheme)

and was followed by later authors (TITOV et al., 1985; LOZOWSKY et al., 1986; GAVRILOVA, 1989, 1992

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

KAZAKH

East Karatau

West Karatau

Karatauchik

Karaduan

Akmysh

Dzharmysh

Shetpe

Tauchik

20 km

Measured and sampled sections

9 - E Dzharmysh 2

I 10 - E Dzharmysh 3

11 - Dzamansauran

1 2 Dzharmysh road

Fault

Chalk (U. Cretaceous)

1 - Dolnapa

2 - Karaduan

3 - Otpan

4 Shair

Lower - Upper Cretaceous Bedding

5 - W Dzharmysh 2

6 - W Dzharmysh 1

7 Dzharmysh cemetery

8 - E Dzharmysh 1

1 3 - Borse

14 - U. Albian ammonite locality

15 • Endikurgan

16 - Chirkala

Jurassic

Triassic

Fig. 1.— Index map of the Gorny Mangyshlak with position of the measured sections and isolated sampling localities.

Fig. I .— Carte dtt Gorny Mangyshlak avec position ties coupes levees et des localizes echantillonnees.

and others). However, Lipatova (1984) and her co-workers split the previously proposed

lithostratigraphic scheme, introducing more units and different chronostratigraphic attributions,

especially for the central part of the succession. Zhidovinov (1994) and VOLOZH et al. (subm.) recently

followed this approach. The Samarkand Scheme is accepted in this paper, with the addition of some

original age data, based on ammonoids, conodonts, palynomorphs and foraminifers (Fig. 2). In most

cases the Russian “svita” is here considered equivalent to the western concept of formation.

The succession is as follows, bottom to top.

Birkut, Otpan and Eolnapa Formations

These units were distinguished mostly in the western part of the area, where they reach an overall

thickness of 2500 m (LOZOWSKY, 1974). However, internal folding probably accounts for several

repetitions and thus the true stratigraphic thickness is considerably less. A figure between 1000 and 1500

in might be realistic, if seismostratigraphic data are also considered (VOLOZH et al ., submit.). The Birkut

Formation consists of green-grey nodular shales, with rare siltstone layers, reddish in the upper part. It is

gradually followed by the Otpan Formation with an increasing occurrence of siltstones and very tine

sandstones, mostly dark grey or green in colour, with very rare, coarser intercalations. Sedimentary

structures are rare with fine, parallel or low-angle laminations, and current ripple-marks. LOZOWSKY

(1974) also recorded thin red siltitic intercalations. The transition to the mostly red sediments of the

Dolnapa Formation is gradual. The best sections are around mount Otpan, south of Shair in West

Karatau, whereas only the upper part of the unit crops out near Dolnapa, in Karatauchik. Red (rarely

green) shales and siltstones dominate, with festoon-shaped medium-grained sandstone intercalations,

and more laterally, persistent bodies of fine-grained sandstones in 10 m-thick packages. Sedimentary

structures are rare, with mostly thin, parallel laminations. The upper boundary was drawn at the

appearance of the first calcareous or dolostone bed, usually a grey shell-lag. However, in the shaly giey-

red uppermost part of the Dolnapa Formation, VlNYUKOV (1966) and LOZOWSKY (1974) repoited

several euryhaline pectinid bivalves, mostly Eumorphotis. The age of this fairly homogeneous

MAURIZIO GAETANI ETAL.

succession is disputed. The Samarkand Scheme by convention draws the Permian/Triassic boundary at

the base of the Dolnapa Formation, without any paleontological evidence. LOZOWSKY el al. (1986)

found megaplant remains ( Pleuromeia) in the Birkut Formation, that they considered of Triassic age.

Moreover" sporomorphs obtained in a borehole from the Otpan Formation in East Karatau were

attributed to the Early Triassic by LOZOWSKY el al. (1986). On the contrary, Zhidovinov (1994),

followed by FEINBERG et al. (1996) and Volozh et al. (subm.), still drew the P/T boundary at the base

of the Dolnapa Formation. Since the palaeontological evidence of LOZOWSKY et al. (1986) has not yet

been challenged and no new palaeontological evidence has been presented, we concur with LOZOWSKY

that all the terrigenous successions that crop out in West Karatau are Triassic in age. The environment

was mostly continental, with large alluvial plains in which overbank deposits were predominant on low

gradient rivers. Lakes and swamps were also identified by V.I. Zhelezko (Ekaterinburg University)

within the Dolnapa Formation (pers. comm.). Red colour suggests oxic conditions in a semi arid climate.

The top of the Dolnapa Formation indicates that brackish to euryhaline conditions were gradually

established on the previous coastal plains.

Karatauchik . Western Karatau

\\J Sha,r

W Dolnapa Karaduan Akmysh

Eastern Karatau

Shair Fm.

Akmysh Fm.

§1

u Z

Karaduan Fm.

M. Trias

Karadzhatyk

Fm.

'Stacheites Beds"

Tartaly

Fm.

Columbites Beds'

"Tirolites" Beds

Dorikranites .Beds

•

Dolnapa Fm.

Otpan Fm.

No outcrops

Birkut Fm.

r 800 m

■*-» _

- Red shales, siltstones and

— «

3 £

- verv fine sandstones

-400 m

c .2

u —

£ 55

ii Grey and red siltstones with

. - verv fine sandstones

^0 m

C rt

<3 B

Grey shales with siltstone

intercalations

p-—-ii Mudstone/wackestone, occasionally packstone

1 ~ r 1 with shaly intercalations

□ Green and grey siltstones with occasionally

very fine sandstones

1° • °| Red and grey litharenites

Fig. 2.— General scheme of Triassic formations with main continental to shallow marine environments and

transgression/regressions.

Fig. 2 .— Schema generaI des formations du Trias avec les principaux environnemenls continentaux et marins et les

transgressions - regressions.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Tyururpa Group (Tartaly and Karadzhatyk Formations)

This group has been studied extensively, especially because of its fairly abundant ammonoid content

(Bajarunas, 1936; Astakhova, 1960, 1964; Shevyrev, 1968, 1990; Kummel, 1969; Lipatova,

1984; Titov et al., 1985; Lozowsky etai, 1986; Gavrilova, 1989, 1992, 1995; Zhidovinov, 1994).

The best outcrops are in the western part of the range, whereas to the east the most typical facies are

reduced in thickness and more difficult to distinguish from the other terrigenous units. We measured the

Dolnapa section in Karatauchik and found it to have a total thickness of 732 m. LOZOWSKY (1974)

reported a thickness of 840 m. This difference may be linked to the interpretation of minor faults.

The Group may be subdivided into three parts (Fig. 3). The lower part is dominated by siltstones and

very fine-grained sandstones, in thin to medium-thick parallel-laminated beds. It contains significant

calcareous intercalations, especially in the lowermost part, and reaches a thickness of about 250-300 m.

In the middle part, about 300 m-thick, up to 2 m-thick local calcareous beds with brachiopods and small

calcareous concretions, packed with ammonoids, are embedded in a grey-green shaly to silty succession.

In the third part (200-250 m thick) that is attributed to the Karadzhatyk Formation, grey-green siltstones

and very fine-grained sandstones dominate, always in thin beds with almost no sedimentary structures.

The upper boundary is marked by the appearance of red siltstones and rare red-brown sandstones. The

ammonoid and bivalve content was illustrated by ASTAKHOVA (1960, 1964), SHEVYREV (1968, 1990)

and Gavrilova (1989, 1992, 1995), and the sequence of the ammonoid faunas was established in the

sixty’s (GAVRILOVA & KURUSHIN, 1986). However, a report of a bed-by-bed sampling was never

published. In Fig. 3, we report the distribution of the ammonoids collected in two sections. The

discovery of conodonts and the first finding of foraminifers from the Triassic of the Gorny Mangyshlak,

allowed us to date these strata more precisely. The palynological content shows high thermal maturity.

For this reason, the microflora is not always well preserved and its occurrence is discontinuous

throughout the succession.

Dorikranites-Tirolites Beds

Conodonts in the upper part of the Dorikranites Beds, typical of the lower part of the Tyururpa

Group, allowed this endemic ammonoid fauna to be dated. Sample MK 277 from the north side Otpan

Mountain section yielded a few specimens of Neospathodus cf. N. brevissimus Orchard, whose range is

possibly early Spathian (Orchard, 1995). In the Dorikranites Beds of the Otpan section, recrystallized

fragments of macrofauna, microgastropods and the foraminifer Lituotuba ? sp. are frequent. In the

Dorikranites Beds of the Dolnapa section, only microgastropods occur. In the upper part of the Tirolites

Beds the foraminifers Tolypammina ex. gr. gregaria Wendt and Nodosaria sp. are present.

Palynological assemblages from the base of the Dorikranites Beds to the top of the Tirolites Beds

(Dolnapa section, samples MK 196 to MK 215), are characterized by Endosporites papillatus Jansonius

associated with Lunatisporites noviaulensis (Leschik) Foster and Lunatisporites spp. (Table 1, Fig. 4). In

the lower part of this interval, few specimens of Krauselisporites sp. were recorded, while rare

Corisaccites stradivarii Utting and Uvaesporites sp. characterize the upper portion (MK 215).

Stratigraphic analysis of the microflora indicates an Induan-early Olenekian age. For further discussion

see the paragraph below on the Stacheites Beds.

Columhites Beds

In the Columhites Beds, the conodonts Gondolella cf. jubata Sweet, Neospathodus symmetricus

Orchard, N. abruptus Orchard, and N. homeri (Bender) indicate a mid Spathian age (ORCHARD. 1995).

Other microfossils, such as microgastropods, ostracods, and foraminifers, are also frequent. Amongst the

latter, Tolypammina ex. gr. gregaria Wendt, Planiinvolutal sp. (ex gr. carinata Leischner), Nodosaria

hoae (Trifonova), N. aff. hoae (Trifonova), N. cf. ordinata Trifonova, N. aff. pseudoprimitiva Efimova,

N. cf. shablensis Trifonova, N. sp., “Frondicularia" ex gr. elegantula K.M.-Maclay, Lenticulina ex gr.

MAURIZIO GAETANI ETA I..

Fig. 3.— The two stratigraphic sections measured in the Tyururpa Group: North side Otpan Mountains and Dolnapa. with

ammonoid range of the Columbites Beds in Dolnapa section. Species of Tirolites are in inverted commars, because the

generic attribution needs revision.

Fig. 3.— Les deux coupes stratigraphiques levees dans le groupe de Tyururpa: versant nord des Montagues Otpan et Dolnapa,

avec les repartitions des ammonites des niveaux a Colombites pour la coupe de Dolnapa. Les especes de Tirolites sont

entre guillemets car!'attribution generique necessite une revision.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Table 1.— Dolnapa section. Lower Triassic. Range chart of the most significant palynomorphs. The four semi-quantitative

categories were established by averaging the number of palynomorphs counted for each taxon on three microscope

slides, A form was classified as rare (R) if it averaged between 0 and 3 specimens, common (C) between 3 and 10

specimens, frequent (F) between 10 and 20 specimens and abundant (A) if more than 20 specimens.

Tableau 1 . — Coupe de Dolnapa, Trias inferieur. Repartition des palynomorphes les plus signifwatifs. Les quatre categories

semi-quantitatives ont ete etablies par moyennes du nombre de specimens de palynomorphes pour chaque taxon sur

trois lames minces. Une forme est qualifiee de rare (R) quand la moyenne est comprise entre 0 et 3 specimens, commun

(C> entre 3 et 10 specimens, frequent (F) entre 10 et 20 specimens et abondanl (A) si plus de 20 specimens.

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goettingensis (Franke), Astacolus spp. were identified. These foraminifers appear to be typical of the

Olenekian of the West Caucasus and Precaucasus (EFIMOVA, 1991). The organic facies show high

thermal maturity. The palynological content is very scarce. Only a few specimens of Densoisporites spp.

and ol acritarchs ( Veryhachium sp.) were recognized (sample MK 219). In the basal part of the

Columbites Beds, DAGYS (1974) reported the brachiopods Piarorhynchella mangyshlakensis Dagys,

Costispiriferina mansfieldi Girty, Spingerellina pygmaea Dagys and Fletcherithyris margaritovi

(Bittner).

Stacheites Beds

No conodonts were found in the Stacheites Beds, and consequently the age of the top of the Tyururpa

Group can be defined only with ammonoids and palynomorphs. The genus Stacheites was reported from

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Nevada (Tobin Range, KUMMEL, 1969; Humboldt Range, Silberling & Wallace, 1969), from the

Anarak region in Iran (TOZER, 1972) and from Dalmatia (KlTTL, 1903). Bed-by-bed data are available

from the Anarak region where the genus was reported from the mid-upper Spathian, and from the

Humboldt Range, where Stacheites was found in the next to the last zone of the Spathian. The mid-late

Spathian age of the top of the Tyururpa Group is also supported by the occurrence of Kazakhstanites,

which was found above Stacheites, but below the Anisian faunas, in the Anarak region (TOZER, 1972).

Above the Stacheites Beds, the microflora is represented by the first occurrences of Densoisporites

nejburgii (Schulz) Balme, Densoisporites playfordii (Balme) Balme and Lundbladispora sp., along with

a decrease in the abundance percentage of Endosporites papillatus (MK 299). The most diversified and

abundant microfloral assemblage (samples MK 298 and MK 297) yielded Densoisporites nejburgii,

Endosporites papillatus, Lundbladispora sp.. Lundbladispora brevicula Balme, Lunatisporites

noviaulensis, L. pellucidus (Goubin) De Jersey, Lunatisporites spp., Krauselisporites sp., Gordonispora

fossulata (Balme) Van der Eem, Gordonispora sp.; undetermined bisaccates are common. Few

specimens of Crinalites sabinensis Utting, Grebeispora concentrica Jansonius, Striatoabieites richterii

(Klaus) Hart, Protohaploxypinus limpidus (Balme & Hennelly) Balme & Playford, Proto hap loxypinus

sp., Alisporites tenuicorpus Balme were found. Maculatisporites sp. and Calamospora sp. are rare.

The presence of important stratigraphic taxa, such as Endosporites papillatus and Densoisporites

nejburgii, allows a fairly precise correlation of the Stacheites Beds. According to FISHER (1979), E.

papillatus and L. singhii, associated with several species of Densoisporites and Lundbladispora,

together with Lunatisporites and Protohaploxipinus, are representative of Zone I and Zone II (Induan) in

the North American Lower Triassic. In this zonation, the younger association (Zone II, upper Induan) is

characterized by the presence of Corisaccites alatus, Densoisporites nejburgii, Lundbladispora

brevicula and L. echinata. The overlying Zone III (lower Olenekian) is based on the appearance of the

monolete cavate spores of lycopsids such as Aratrisporites and Zone IV (upper Olenekian) is defined by

an assemblage which includes the previous taxa, plus the appearance of Guttapollenites hannonicus, but

lacks E. papillatus.

The zonation of the Lower Triassic sequences in the Barents Sea, Svalbard, former USSR and

Sovietic Arctic islands provides further data. HOCHUL1 et al. (1989) assigned:

— an early Olenekian age to Assemblage N containing abundant P. fungosus, a diversified association

of cavate spores, and characterized by the LADs of Densoisporites complicatus, D. playfordii and

Naumovaspora striata.

— a late Olenekian age to Assemblage M containing D. nejburgii, Krauselisporites, Lundbladispora ,

Rewanispora.

The distribution of E. papillatus in the Lower Triassic of Europe extends from the Induan to the

upper Olenekian, while D. neiburji is present only in the upper Olenekian (VlSSCHER & BRUGMAN.

1981, 1986; BRUGMAN, 1986).

Fig. 4.— Selected taxa of sporomorphs and dinoflagellate cysts from the Triassic and Middle Jurassic rocks of Mangyshlak.

Specimens photographed in plain transmitted light. Magnification x 350 (a-f) and x 525 (g-s).

Fic.4 .— Quelques specimens de microflore et de kystes de dinoflagelles du Trias et dit Jurassique moyen dit Mangyshlak.

Specimens photographies en lumiere transmise. Grossissement a-J':x 350: g-s: x 525.

a, Endosporites papillatus Jansonius, 1962 (MK 204); b, Grebespora concentrica Jansonius, 1962 (MK 298); c,

Lunatisporites pellucidus (Goubin) De Jersey, 1971 (MK 298); A, Densoisporites playfordii (Balme) Balme, 1970 (MK

299); e, Lundbladispora brevicula Balme, 1970 (MK 298); f, Veryhachium sp. (MK 215); g. Nannoceratopsis gracilis

Alberti, 1961 emend. Evitt, 1962 (MK 17-1, England Finder coordinate V35-3); h. Nannoceratopsis spiculata Stover,

1966 (MK 17-1, England Finder coordinate K 36-2); i, Nannoceratopsis gracilis Alberti. 1961 emend. Evitt, 1962 (MK

64-2. England Finder coordinate F 29-2); 1, Mendicodinium spinosum Bucefalo Palliani et al.. 1997 (MK 17-1. England

Finder coordinate G 44-1); m , Susadinium scrofoides Dorhofer & Davies, 1980 emend. Below. 1987 (MK 17-1,

England Finder coordinate G 31 -1); n, Susadinium scrofoides Dorhofer & Davies, 1980 emend. Below. 1987 (MK 17-1.

England Finder coordinate O 36-1); o. Reutlingia cordobarbata Below, 1987 (MK 17-1, England Finder coordinate

J34-I); p, Parvocysta nasuta Bjaerke, 1980 (MK 17-1, England Finder coordinate G 35-1); q , Mendicodinium

semitabulatum Morgenroth. 1970 (MK 17-2, England Finder coordinate D 29-3); r. Lycopodiumsporites

austroclavatoides (Cookson) Potoni. 1956 (MK 17-1); s, Coronatisporites valdensis (Couper) Dettmann, 1963 (MK 17-

1 ).

MAURIZIO GAETANI ET AL.

On the basis of the references cited, the presence of E. papillatus throughout the section allows the

Tyururpa Group to be attributed to the Early Triassic, and possibly the base of the Group to the

Olenekian. The first occurrence of D. nejburgii in sample MK 299 (upper part of the Stacheites beds)

definitively indicates the upper Olenekian.

In conclusion, the age of the Tyururpa Group seems to be restricted to the Olenekian. The few

conodonts found in the upper part of the Dorikranites Beds suggest a Spathian (late Olenekian) age,

whilst the palynoflora hints to a slightly older age assignments. This is why we do not definitively rule

out a possible early Olenekian age for the very base of the Tyururpa Group.

Environment

The occurrence of marine fauna decreases eastwards, and in the East Karatau and Kugusem Scarp in

the Ustyurt Plateau only Dorikranites was recorded (SHEVYREV, 1990, LOZOWSKY, 1974; GAVRILOVA,

1989, 1992). Lithological correlations made by SHLEZINGER (1965) and LOZOWSKY (1974) tried to link

the East Karatau to the better-constrained western parts of the range.

In Karatauchik and in part of West Karatau, the Tyururpa Group was deposited under marine

conditions. Calcareous shell lags, that may be considered as storm deposits, are most typical. Also

coquinoid levels at the base of Tirolites s.l. Beds suggest a shallow subtidal accumulation under a

current regime. Most of the Columbites Beds were deposited instead in a quiet, poorly oxygenated

environment, with ammonoid accumulation that allowed the formation of calcareous concretions, in

which packed ammonoids were crushed during burial compaction. However, freshwater runoff was

present, because Estherids and Labirintodonts were found (LOZOWSKY, 1974). A gradual return to more

marginal conditions is indicated by the Karadzhatyk Formation, with the finding of terrestrial

megaplants like Pleuromeia sternbergii (Muenster) Corda (Dobruskina, 1982). Occasional ammonoid

remains still indicate local marine influence, at least in the westernmost part of Mangyshlak.

Organic facies

Due to the high thermal maturity, the organic facies are not a very useful tool for detailed

palaeoenvironmental and palaeoecologic considerations. The percentage of terrestrial versus marine

material, represented by few species of acritarchs, is high in the entire section.

The percentage of palynomacerals (inertinite and vitrinite) and palynomorphs is constantly high.

Inertinite is mostly equidimensional and vitrinite particles are commonly unrounded and unsorted.

Amorphous organic matter is present in very low percentage, or absent. These data suggest an

oxygenated marine environment, probably characterized by high terrestrial input, and probably not far

from the shoreline. The palynofacies suggest a depositional palaeoenvironment proximal to the

continental area, where the parent floras developed. This proximal condition seems to be more evident

in samples MK 298 and MK 297. These levels contain abundant and diversified (in number and species)

microflora, suggesting a close proximity to the source area. Among the marine microorganisms,

acritarchs are present in very low percentage throughout the section, with a relative increment in sample

MK 208. The most represented genus is Veryhachium, and only at the top of the section the presence of

Micrhystridium sp. was recorded.

Sequence stratigraphy

Three cycles may be identified in the Tyururpa Group. The first cycle starts with a transgression

recorded by the dolostones, shell-lags and calcareous lenses of the Dorikranites Beds. It is followed by

several parasequences of fine sandstones and siltstones suggesting a regression or an increased sediment

supply. A second cycle may be identified with the Tirolites s.l. Beds, with a transgression marked by the

basal coquinoid bed. The final cycle starts with a transgression recorded by the basal calcareous

horizons, has the maximum flooding within the Columbites Beds, and the high standing with gradual

filling of the basin at the time of the Karadzhatyk Formation.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Karaduan Formation

The overlying succession is probably the most problematic. In the Dolnapa section (Karatauchik), the

grey-green shales and siltstones of the Karadzhatyk Formation are overlain by red shales and very fine¬

grained sandstones, followed in turn by festooned, brown sandstones, rare calcareous beds, dark

claystones and again shelly calcareous beds (Fig. 5). South of Karaduan, in the West Karatau, the

absence of the Columbites Beds, which provide a firm base for correlation, makes it difficult to trace the

lower boundary of the Karaduan Formation. Consequently, a 200 m-thick succession of grey-green

siltstones, shales and fine grained sandstones, containing several calcareous shell lags, was tentatively

attributed to the Karadzhatyk Formation. The portion displaying an increase of sandstones and

disappearance of calcareous shell lags

Fig. 5.— The Karaduan Formation at the top

of the Dolnapa section and the SW Karaduan

section.

FlG. 5 .— La formation Karaduan au sommet de la coupe

de Dolnapa el au sommet de la coupe de

Karaduan sud ouest.

was

chosen as the lower boundary of the Karaduan

Formation. Positive correlations become

increasingly difficult eastwards, where

continental conditions were more prevalent. In

the Karaduan area, above the last calcareous bed

which yielded a few specimens of bakewelliids

and modiolids, grey-green fine-grained

sandstones in 10-20 m-thick packages follow,

reaching a total thickness of about 300 m. They

are overlain by at least five coarsening-up

parasequences, each 20-40 m-thick, consisting of

grey to red siltstones up to medium sandstones.

In some cases, typical point bar and channel

fluvial structures, each a few metres thick, may

be observed. They are in turn overlain by the

shale and limestone beds of the Akmysh

Formation. This unit with calcareous shell lags

yielded several euryhaline bivalves, mentioned

in ANONYMUS (1973), the Samarkand Scheme

(1977), and by LOZOWSKY (1974) and

Lipatova (1984). A few foraminifers, common

in the Middle and Upper Triassic, were observed

in the lower part of the Karaduan Formation in

the Dolnapa section, i.e. Planiinvoluta carinata

(Leischner) and Tolypammina gregaria Wendt.

They are eurybionthic forms which live attached

to the bottom or to other faunal elements. A firm

age assignment is difficult. Usually a Middle

Triassic age is suggested. In the Dolnapa section,

a microflora similar to that of the Stacheites

Beds, suggesting still an Olenekian age, was

found (sample MK 293). Recently, Lipatova

( 1984) and especially Zhidovinov (1994)

provided a different interpretation for the

succession. They distinguished the lower unit as

“Karaduan Svita” in which marine intercalations

are still present, assigning it to the Early Triassic

on the basis of charophytae specimens. They

named the more arenaceous unit, in which

Zhidovinov (1994) recognized a large input of

“tuffogenic” material, "Khozbulak Svita” and

divided it into three parts. According to

Zhidovinov (1994), the age of Khozbulak is

MAURIZIO GAETANI ETAL.

Middle Triassic. We think it is fairly hard to fit all of the Karaduan Formation sensu ZHIDOVINOV in the

Early Triassic, because the ammonoid beds of the underlying Tyururpa Group already represent most of

the Spathian. Moreover, a firm correlation of the charophytae data to other more tested biostratigraphic

scales is yet to be demonstrated. Consequently, we prefer to maintain a generic Middle Triassic age lor

most of the Karaduan succession sensu lato.

Environment

The lower part of the section contains several episodes of transitional to coastal sedimentation, with

rare episodes of shelly storm deposits. The upper, thicker part, consists of alluvial plain cycles, with

increasing energy and meandering river episodes.

Sequence stratigraphy

In the lower part, a stratigraphic interpretation of the sequence may still be attempted. Two sequences

are recognizable in which the calcareous horizons indicate the MFS. The lack ot biostratigraphic control

in the upper portion hampers any clear interpretation.

Akmysh Formation

The fairly abrupt change of sedimentation may suggest a paraconformity at the scale of the outcrop

(Fig. 6). The fine to medium-grained sandstones of the Karaduan Formation are overlain by dark grey

mudstones-wackestones in 20-40 cm-thick beds, alternating with green-grey splintery shales and rarely,

very fine-grained sandstones. Commonly, the top of the calcareous layers contains a gastropod/bi valve

assemblage, with mud-supported shells. A few dark siliceous crusts and small nodules are also present.

Burrowing is usually dense. In the first 310 m of the unit, the mudstone/wackestone to terrigenous ratio

(usually shales) is about 1:2. Very fine-grained sandstones are very subordinate. On the contrary, the

upper part of the unit, about 200 m-thick, is mostly shaly with rare marly intercalations. The fossil

content is fairly abundant in the lower part, where density and low diversity of gastropod/bivalve

assemblages indicate a restricted environment. Dasycladacean algae are significantly absent. A few

foraminifers ( Ophthalmidium sp.) were identified at about 145 m from the base of the unit. The finding

of palynomorphs near the base of the unit is most important. All samples show a very high thermal

maturity and palynomorphs are scattered and badly preserved. The most important palynomorphs found

in these samples (MK 254, MK 257) are: Camerosporites secatus Leschik emend. Scheuring 1978,

Enzonalasporites vigens Leschik, Cycadopites sp., Partitisporites spp., Ovalipollis pseudoalatus

(Thiergart) Schuurman and very rare specimens of Patinasporites densus Leschik emend. Scheuring

1970.

This assemblage can be assigned to the Camerosporites secatus phase, which is generically

considered as a Ladinian-Carnian event (SCHUURMAN, 1977, 1979; VISSCHER & KRYSTYN, 1978;

Visscher & Brugmann, 1981; Van der Eem, 1983 ; Fisher & Dunay, 1984). The presence of

Patinasporites densus and E. vigens suggests a Carnian age (VISSCHER & KRYSTYN, 1978; VISSCHER &

Brugmann, 1981; Warrington, 1996). The scarcity of more age-specific microflora does not allow

more precise dating at the substage level.

Environment

The lower part is considered a restricted, coastal marine flat, periodically invaded by fine-grained

terrigenous detritus. Gradually the clay input becomes dominant and the upper part of the unit is

interpreted as a muddy coastal flat.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Fig. 6.— Akmysh and Shair Formations in the W Karaduan and

Shair sections.

Fig. 6 .— Les formations Akmysk el Shair dans les coupes du

Karaduan ouesi et de Shair.

Sequence stratigraphy

The lower boundary of the Akmysh

Formation is interpreted as a sequence boundary

with the calcareous/shaly lower part as the

transgressive system tract. All other parts of the

sequence are difficult to recognize.

Shair Formation

The overlying Shair Formation may be

subdivided into three parts, bottom to top (Fig.

6 ).

The lower unit consists of grey to green, fine¬

grained sandstones, forming 1-4 m-thick

amalgamated packages, occasionally with faint

parallel laminations. The sandstone layers are

subdivided by thicker packages of splintery

shales and siltstones. The basal TOO m are richer

in sandstones and form cliffs. Gradually, the

sandstone content and size decrease and

siltstones and shales prevail for more than 200 m.

The arenaceous layers, presenting very few

parallel laminations, have a great lateral

continuity.

The intermediate unit is characterized by a

weak recovery of the carbonate sedimentation,

with dark grey marly limestones, marls and marly

siltstones, which form ridges, about 20 m-thick,

with persistent lateral continuity. The total

thickness of this unit is about 50-60 m. No

foraminifers were detected, but only fragments of

macrofauna. The bivalves Trigonodus

hornschuchi Berg., T. (?) roeperti (Berg.),

Myophoriopsis g re ga nodes (Philippi), Mytilus

(Falcimytilus) nasai (Kobayashi & Ichikawa)

were reported from this unit (LIPATOVA. 1984;

Zhidovinov, 1994).

The upper part of the formation consists once more of dark grey to green shales and siltstones, with

subordinate very fine-grained sandstones. The thickness is highly variable, depending on the subsequent

Late Triassic and Early Jurassic erosion. The top of the unit may preserve an alteration cap. with a

varicoloured silcrete, tens of m-thick, like in the two large gullies immediately to the east of Shair.

The thickness of the Shair Formation is usually more than 500 m, but we did not measure the

topmost part.

Environment

The rare occurrence of euryhaline bivalves and the great lateral continuity of the very fine-grained

arenaceous bodies suggest a quiet protected shelf, with euryhaline conditions. Notable is the absence of

dasycladacean algae.

No new data about the age. According to the current literature, the Shair Formation is attributed to

the Carnian-Norian (Zhidovinov, 1994).^

MAURIZIO GAETANI ETAL.

Composition of Triassic sandstones

The samples studied are mostly very fine-grained (Lower Triassic) to fine-grained (Middle to Upper

Triassic) feldspathic litharenites to lithic arkoses (average composition Q=35±9; F=30±7; L-34±6;

point-counting method and parameters after DICKINSON, 1970) (Fig. 7). Detrital quartz increases

significantly with grain size relative to feldspar grains (coeff. correl. GSZ vs. ln(Q/F) = 0.74; sign. lev.

1%); the Q/F ratio increases from as low as 0.5 in very fine sandstones, to as much as 4 in upper tine

sandstones, within the Akmysh Formation. Monocrystalline quartz, rarely showing features diagnostic

of volcanic origin, predominates over basement-derived polycrystalline grains (average C/Q = 15%).

Plagioclase dominates among detrital feldspars (average P/F= 95%); alkali-feldspars are largely

chessboard-albite, with rare orthoclase and perthite. Volcanic lithics are virtually exclusive (V/L =

100%), with predominant felsic types (felsites, microfelsites, spherulites, pumiceous clasts); microlitic

grains are subordinate < 10%. Metamorphic rock fragments (slates, micaschists, paragneisses) are rare

and sedimentary rock fragments are negligible. Micas, opaques, apatite, rutile, zircon, and tourmaline,

along with local silty mudclasts and greenish grains are also found; most significant is the occurrence ot

dark red to coffee brown chrome-rich chromian spinel in the Karaduan, Akmysh and Shair Formations.

Quartzose and albitic syntaxial cements are common in most samples (up to 22% of the rock), as well as

illitic to chlorine epimatrix (up to 17% of the rock). Intragranular porosity is therefore very low. Late

diagenetic carbonates (locally poikilotopic calcite, siderite) are locally abundant (up to 55% ot the rock),

authigenic pyrite, chlorite or hematite are locally

significant. Samples with abundant carbonate

replacements tend to be depleted in rock

fragments relative to quartz (coeff. correl. AUT

vs. ln(Q/L) = 0.59; sign. lev. 5%).

Provenance of Triassic sandstones

Volcanic detritus largely derived from erosion

of intermediate to felsic products (e.g. dacites) is

virtually exclusive in all Triassic sandstones of

Mangyshlak, from the Induan Otpan Formation

to the Carnian-Norian Shair Formation,

suggesting an arc-related source terrane. Average

detrital modes of all Triassic units plot right in

the middle of the QFL triangle, within the

“Dissected Arc” provenance field (Fig. 7;

Dickinson & Suczek, 1979; Dickinson, 1985)

but close to the boundary with the “Recycled

Orogen” provenance field. The Mangyshlak

sandstones are in fact notably enriched in quartz

and feldspars relative to clastic suites typically

found in modern fore-arc to back-arc basins and

derived from oceanic to continental undissected

volcanic arcs; they compare more closely with

siliciclastics characterising triple junction to

strike-slip settings (Gergen & INGERSOLL, 1986;

Packer & Ingersoll, 1986; Marsaglia &

INGERSOLL, 1992). On the other hand, the

invariably high P/F ratio indicates that the

batholithic roots of the arc massif were never

widely exposed, and deepening of erosion levels

with time was slow. Evidence of unroofing of the

volcanic source areas during the Triassic is

Fig. 7.— Average detrital modes for the six Triassic terrigenous

units plot right in the middle of the QFL diagram and all

within the “dissected magmatic arc provenance field"

(Dickinson, 1985), reflecting an excess of detrital

quartz with respect to "normal" volcaniclastic

continental arc suites (Marsaglia & Ingersoll, 1992).

Polygon refers to all studied Triassic samples, and is one

standard deviation each side of the mean. Q= total

quartz; F= feldspars; L= “aphanite" lithic fragments.

Fig. 7. — Le report du mode de moyenne detritique pour les six

unites triasiques au milieu du diagramme QFL et toils d

I'interieur du "champ de provenance de I'arc

magmatique" (Dickinson, 1985) montre un exces de

quartz detritique en ce qui concerne des suites d’arc

volcaniques continentaux “normaux" ( Marsaglia &

Ingersoll, 1992) Le poly gone se rapporte a tous les

echantillons triasiques et est une deviation standard de

chaque cotes de la principale. Q : quartz : F: feld-

spaths : L . fragments de roches aphanitiques.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

subtle, including a slight increase with time of polycrystalline quartz and alkali feldspars (coeff. correl.

vs. C/Q and P/F 0.54 and -0.37 respectively; sign. lev. 10% or higher). Moreover, chessboard-albite is

most abundant, granophyric and holocrystalline hypabissal grains are sporadically observed, and a few

metasedimentary grains hint at a greater contribution from basement wallrocks in the Upper Triassic

Shair Formation. The occurrence of chrome-rich Cr-spinel in several samples suggest provenance from

protrusions of upper mantle rocks emplaced in strike-slip arc settings (HlSADA & Arai. 1993), rather

than from slivers of oceanic lithosphere (DICK & BULLEN, 1984) tectonically incorporated within a

subduction complex.

The geometry of the thick and invariably fine-grained deltaic volcaniclastic wedge, thinning rapidly

towards the south, along with transition to more proximal continental facies in the east, suggest that the

source area was located in the eastern quadrants, at a distance of at least many tens of kilometres (SELF,

1975; Davies eta!., 1979).

The relative abundance of quartz and feldspars with respect to volcanic lithics cannot be totally

ascribed to selective depletion of unstable volcanic grains, due to either pre-depositional (e.g.

weathering, transport, hydraulic sorting) or post-depositional (e.g. carbonate replacement) processes

(CAMERON & Blatt, 1971; Mathisen, 1984; Garzanti, 1986). Rather, dilution from polycyclic

sources cannot be ruled out. An extremely attractive alternative hypothesis is that detritus was not

directly fed from erosion of active volcanoes, but was largely paleovolcanic and derived from a relict arc

terrane of Palaeozoic age (Graham et al., 1993). In fact, broadly comparable compositions characterize

mainly continental Permian to Triassic clastic suites derived from erosion of largely Carboniferous

volcaniclastic assemblages and accumulated in foreland-style basins in Central Asia after the Late

Palaeozoic Altaid-Hercynian orogeny (e.g., Carroll et al., 1995; Hendrix et al., 1996).

The precise geodynamic setting thus cannot be discriminated by the compositional data alone. On

one hand, strongly asymmetric sediment-thickness distribution is consistent with deposition in a retroarc

foreland basin (as inferred by BAUD & STAMPFLI, 1989, for the Triassic of Aghdarband. which lies,

however, some 1000 km to the SE). On the other hand, exclusiveness of homogeneous volcanic detritus

for over 30 m.y. - P/F ratio >90; V/L ratio =100; microlitic/(microlitic + felsitic) lithic type ratio < 10% -

is atypical for provenance from a fold-thrust belt.

THE JURASSIC

The Jurassic succession lies unconformably on several Triassic units, from the Akmysh to the Shair

Formations, sealing a structured palaeotopography. East of Shair it rests almost flat on the Akmysh

rocks, sealing a palaeovalley. Thickness rarely exceed 200 m in a context of low subsidence rate. The

general depositional trend is from fluvial to lacustrine continental deposition in the lower part, onlapped

with successive steps by open, shallow marine sediments.

After pioneering work, the basic stratigraphy of the Jurassic succession was established by the team

of Mokrinsky (VSEGEI) and by the Geological Expedition to Mangyshlak of the VNIGRI

(MUROMCHEV, 1968). This classification was adopted by the Samarkand Scheme (1977). Several papers

dealing with ammonoids, foraminifers, palinostratigraphy, and brachiopods were published

subsequently, i.e. TlMOSHKINA & MENSHIKOVA (1985), KlRICHKOVA el al. (1989) and KlRICHKOVA &

Dolydenko (1996) on palynostratigraphy, Azbel (1979) and Azbel & Hoffman (1982) on

foraminifers, and REPIN & RASHWAN(1996) on Callovian ammonoids.

We worked mostly west to east of the village of Dzharmysh and near Shair (Fig. 1). Most of the area

studied falls in the east Karatau according to the Samarkand Scheme. The following units were

measured and sampled from bottom to top (Fig. 8).

Karadiirmen Formation and Bazarly Formation

These two units consist entirely of terrigenous sediments, and present a very variable thickness

because they seal the underlying palaeotopography. According to the Samarkand Scheme (1977) they

MAURIZIO GAETAN1 ETAL.

Fig. 8.— Measured sections in Jurassic formations in the district of the Dzharmysh village. Eastern Karatau.

Fig. 8.— Coupes levees dans les formations jurassiques du district de Dzltarmysh, est Karatau.

Source: MNHN, Paris

J3ERRIASIAN OXFORDIAN CALLOVIAN ^ BAJOCIAN AALENIAN

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

may reach a thickness of up to 260 m, but usually are thinner than 200 m. Three main lithological

assemblages were identified.

— Dark shales rich in organic matter with coal seams cm to dm-thick. These levels are more diffuse in

the lower part of the unit and were observed mostly east of Shair, where they rest on the silcrete soils

of the topmost Triassic succession. Sometimes this part is also distinguished as Kokala Formation

Unfortunately, the coal seams did not yield any palynoflora, but only macerals with vitrinite and

inertinite, indicating high sorting in a fairly high energy environment.

— Light grey to dark brown medium to fine sandstones, forming ledges a few m-thick. occasionally

with high angle cross-lamination and flat top sets, a few cm-thick. Interference ripple-marks were

also observed and frequent plant fragments, especially leaf imprints, are present. In a few levels,

brackish-water bivalves (Modiolus-\'ike) were observed. At the top of the sandstone ledges a

ferruginous crust may be preserved, with vertical concretions interpreted as remnants of roots.

— Grey to dark grey very fine sandstones, siltites and shales, often poorly exposed, interbedded with the

previous medium to fine sandstones and more abundant in the upper part of the unit. The clay content

is very variable. These lithotypes are predominant over the sandstone with at least a 10:1 ratio.

Cementation is not homogenous, with partially cemented grey sands. In the section E Dzharmysh 1,

the base of a fossil tree in living position was observed.

Age

According to MUROMCHEV (1968) and the Samarkand Scheme (1977), the Karadiirmen Formation

contains vascular plants such as Coniopteris spp., Ptylophyllum spp. and Nilssonia spp. and brackish-

water bivalves. The age is bracketed between the Aalenian and the Bajocian. The following Bazarly

Formation may indicate a Bajocian age, with the first marine spells yielding a few ammonoids of the

Parkinsonia group and trigoniid bivalves.

The E Dzharmysh I section was sampled for palynostratigraphy (samples MK 61 to 68) (Table 2). In

the lower part (MK 61 to MK 63) samples are barren of palynomorphs and the palynofacies consists of

vitrinite (about 80%) and inertinite (about 10%). Rare tracheids were observed. When pollens are

present (MK 63), the most abundant constituents are trilete spores of Pteridophytae. Bisaccate pollens

are rare. This organic composition is related to a very near-shore palaeoenvironment, where the heaviest

pteridophytic spores are concentrated. The palynofacies records a significant change from sample

MK 65 up to MK 68, where the marine influence becomes very strong. The most abundant organic

constituents are Botryococcus, frequently associated with Pediastrium and Tasmanites, algae that are

very tolerant of euryhaline conditions and typical of transitional environments. A significant feature of

the sporomorph assemblages is the common occurrence of Araucariaceae-type pollen (.Araucariacites

australis Cookson and Callialasporites minus (Tralau) Guy). In the Lower Jurassic, a rapid distribution

of Araucariaceae-type pollen coincided with the decline of Classopollis. This Toarcian event was

l/>

111 i 11

If ? * 1 a 1 | * » 1 I 1 1 1 1

11 f 3I!I!I 1 i 1 1 ! I I I § 8 i

1 1 i 1 It 111 11 1! i If ! 11!

I 4 f !• 1 ' t $ 5111 § 31. II1112

MK 68

MK 67

MK 66

MK 64

MK 63

MK 61

C A R RRA RRRFRR

CCRARRCAAR R R

Table 2.— Semi-quantitative stratigraphical range of

selected sporomorphs and dinoflagellate cysts from

the Jurassic of the E Dzarmysh 1 and 2 sections. (A:

abundant; F: frequent; C: common; R: rare).

Tableau 2 .— Repartition stratigraphique semi-quantitative

de palynomprphes selectionnes et de kystes de

dinoflagelles du Jurassique des coupes Est

Dzarmysh I et 2 (A : abondant: F : frequent: C :

commun ; R : rare).

MAURIZIO GAETANI ET At..

recorded in Europe (SCHULZ, 1967; HOELSTAD, 1985), Argentina (VOLKHEIMER & QUATTROCCHIO,

1981) Australia (FlLATOFF, 1975), Greenland (LUND & PEDERSEN, 1985), the Netherlands

(HERNGREEN & DE BOER. 1974) and Sweden (GUY-OHLSON, 1989). The first occurrence of A. australis

in the Perth Basin was referred to the E. tumulus zone (Lower Jurassic). This taxon became abundant in

the C. dampieri zone (late Toarcian and Middle Jurassic). Leptolepidites spp., recorded in the E

Dzharmysh 1 section, is a typical Middle Jurassic taxon (Tralau, 1968; GUY. 1971).

The Mangyshlakh sporomorph assemblage includes all the index taxa of phase VI of VISSCHER et al.

(1980), such as Ischyosporites spp., Callialasporites sp. and Leptolepidites spp. Callialasporites minus ,

present in sample MK 64. was reported from Australia and Sweden. In Sweden, its range is from

Bajocian to Bathonian (Guy. 1971). The sporomorphs assemblages from the E Dzharmysh 1 section

may be referred to the transition between the E. tumulus zone (Hettangian-Bajocian) and the C. dampieri

zone (Bajocian - Kimmeridgian) of FlLATOFF (1975), due to the presence of C. minus associated with

common Araucariacites australis, and the absence of Classopollis and Callialasporites dampieri.

Rare dinoflagellate cysts were found throughout the section. They are represented mainly by long-

range taxa. Mendicodinium umbriense Bucefalo Palliani, Riding & Torricelli, a Toarcian taxon with

Tethyan affinity was recorded. Nannoceratopsis gracilis Stover and Mancodinium semitabulatum

Morgenroth. taxa with stratigraphic ranges from late Pliensbachian to Callovian and from late

Pliensbachian to early Bajocian respectively, were also found.

In conclusion, our data confirm an earliest Middle Jurassic age for the Karadiirmen Formation

On the contrary, we failed to find ammonoids in the Bazarly Formation and palynomorphs were also

not found in the E Dzharmysh 2 section. The content of organic matter is very low and the exclusive

presence of inertinite suggests a strong oxidation of the palaeoenvironment.

Environment

The Karadiirmen Formation was deposited in a continental environment. The topographic relief on

which it aggraded was not fully peneplaned. as indicated by palaeovalleys filled by the Karadiirmen

Formation or by the the Kokala Formation where the last unit is present. However, the sandstone grain-

size and the abundance of coaly shales deposited in water ponds and marshy Hats in the lower part of the

unit suggest that the topographic gradient was low. An alluvial plain with small meandering rivers and

possibly coastal lagoons, where brackish bivalves might also dwell, was a likely environment. Due to

the wandering course of the rivers, ferruginous crusts could develop during episodes of non deposition.

The inertinite is blade-shaped and suggests selection processes during the sedimentation. The organic

content reveals a well-oxygenated palaeoenvironment, where the degradation of the hydrogen-rich

organic matter is complete. The climate was humid. The upper part of the Karadiirmen Formation

suggests an increased marine influence. An environment similar to the overlying Bazarly Formation,

where temporary ingressions produced thin levels with ammonoids, is hypothesized. However, the bulk

of these two units was formed in a continental environment under well-oxygenated conditions.

Sequence stratigraphy

Lack of sufficient biostratigraphic control does not allow sequences to be recognized.

Sarydiirmen Formation

The base of the formation was defined with the appearance of grey and brown shales, silty and sandy

in the basal metres, that transgress over a condensed horizon with a siliceous brown crust. The

Sarydiirmen Formation consists of grey shales in which very thin horizons of silts and very fine sands

may occur. Pure claystones are rare.

This succession, about 20-25 m thick, ends with bioturbated shaly sands, gradually becoming more

sandy, and is capped by a peculiar layer of grey/brown sandstones to hybrid sandstones with calcareous

Source: MNHN. Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

cement, here attributed to an overlying unit. The total thickness of the Sarydiirmen that we measured is

in contrast with the up to 100 m reported in the Samarkand Scheme (1977).

AGE

The shales were sampled for nannofossils but none were found. Palynomorphs are also scarce, even

if at the base (sample MK 13) the palynofacies is dominated by terrestrial organic matter

(palynomacerals and sporomorphs), while marine constituents are rare and dinoflagellate cysts are

absent. Most interesting is the dinoflagellate cyst assemblages recorded in samples MK 14 and MK 17

(section E Dzharmysh 2). Both samples yielded taxa belonging to the Parvocysta suite of Riding

( 1984). Rare specimens of Parvocysta ? tricornuta Riding & Shaw were recorded in sample MK 14

while sample MK 1 7 contains a high percentage of Susadinium scrofoides Dorhofer & Davies emend.

Below and Parvocysta nasuta Bjaerke (Table 2).

In the Boreal Realm, this dinoflagellate suite shows a very restricted range, between the upper

Toarcian (H. bifrons Zone) and the lower Aalenian (L. opalinum Zone) (Riding & Thomas, 1992). This

stratigraphic range was recorded also in Russia (Siberia) by Ilyina et al. (1994). The specimens of S.

scrofoides recorded in the assemblages are characterised by a spinose and/or granulose autophragm, a

morphological feature typical of the Aalenian S. scrofoides (BUCEFALO Palliani & Riding, in press).

In sample MK 17, long-range species, such as Nannoceratopsis spiculata Stover, Nannoceratopsis

gracilis Alberti emend. Evitt and P. halosa (Filatoff) emend. Prauss were recorded. On the basis of this

assemblage the sample may be tentatively referred to the early Aalenian.

This finding, just below the layers with Callovian ammonoids, is somewhat puzzling and suggests

the need for improvement of the Middle Jurassic stratigraphy in Gorny Mangyshlak. A gap at the lop of

the Sarydiirmen Formation was suggested also by KlRIKHOVA et al. (1989) on the basis of

palynomorphs.

Environment

The presence ol dinocysts suggests a marine influence in the upper part of the terrigenous succession.

The dominant shaly facies with rare fine siltitic intercalation indicate a marginal sheltered environment,

where connections with the open ocean were episodic and sedimentation gaps could occur locally.

Unnamed Unit

A thin unit lies between the shales of the Sarydiirmen Formation and the overlying mudstones and

shales ol the Chagabulak Formation. The succession is not named in the Russian literature, and even in

RlI’IN & Rashwan( 1996), it is reported by its age only.

It consists of two layers of grey/brown sandstones to hybrid sandstones with calcareous cement,

separated by a silty/shaly bed containing isolated, well preserved zircon crystals. The total thickness of

this unit varies from 2 to 6 m and it is sealed by a ferruginous crust, up to 20-30 cm thick, that forms a

continuous horizon in the landscape.

The two sandy/hybrid layers contain an abundant marine fauna, with clusters of brachiopods, large

isolated oysters and sparse ammonoids. The very abundant brachiopod Rhynchonelloidella sp. (det. B.

Lam in. Dijon) forms clusters, possibly still in life position, whilst the shells of Liostrea sp., up to 10 cm-

kuge. appear isolated and reworked. The two sandy/hybrid layers yielded ammonoids of the Calloviense

Zone (top ol the early Callovian; Fig. 9, Table 3). However, about 2 km west of Dzharmysh (section W

D/liannysh 2), the top of the sandy layers contains ammonoids from the Coronatum Subzone of the

Huddle Callovian (MK 95). A very reduced or condensed middle Callovian is suggested also by REPIN

& Rashwan (1996), who were able to identify ammonoids from the Koenigi Zone, immediately

underlying the Calloviense Zone. Amongst the microfossils, calcations nannofossils are very rare, with

ew Watznaueria sp. found at the top of the unit where foraminifers are also very rare. In section W

MAURIZIO GAETANI ET AL.

Dzharmysh 2, Textularia jurassica Guembel (sample N 5059) and Ammobaculites ? sp. (sample N 5061)

were identified.

This unit is well constrained to the upper part of the early Callovian. locally to the middle Callovian

in the condensed layer. On the contrary, according to KlRlCHKOVA & DOLYDENKO (1996, lig. 6) the top

of the Bathonian and the lower Callovian are missing in the Mangyshlak.

^ ! lybrid sandstone

Shale

W DZHARMYSH 1

DZHARMYSH

CEMETERY

E DZHARMYSH 2

Mudstone

Ferruginoas crust

W DZHARMYSH 2

MK 95 MIDDLE

CALLOVIAN

(Coronalum

Zone)

r 10m

_ 0

r 100 i

L- 0

Zone

1 MK 19— Calloviense

MK is Zone

Fig. 9.— Ammonoid range in the Callovian-Oxfordian layers.

Fig. 9.— Repartition des ammonites dans les niveaux calloviens - oxfordiens.

Environment

This unnamed unit indicates the gradual but generalized ingression of an epicontinental sea on the

peneplaned flat of the southern shores of Asia. The final drowning of the near shore coarser terrigenous

sediments and the reduced and condensed chemical precipitation of the ferruginous crust are recorded

during the middle Callovian. The well-preserved zircon crystals suggest a remote, contemporaneous

volcanic activity.

Sequence stratigraphy

The hybrid shelly sandstone layers are considered as the Transgressive Tract, whilst the ferruginous

crust corresponds to the maximum Hooding and starved basin stage. A similar condensed sedimentation

and reduced layers were recognised throughout western Europe in the upper Callovian by NORRIS &

HALLAM (1995).

Composition of Middle Jurassic arenites

Several sandstone samples were collected in the previous Jurassic formations and 5 were point-

counted (MK 6, MK 59, MK 131, MK 21. MK 41). The arenites studied are fine-grained feldspathic

Source: MNHN , Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Table 3.— List of the identified ammonites in the Callovian-Oxfordian of the area around Dzarmysh village.

Tableau 3.— Liste des ammonites reconnues dans le Callovien - Oxfordien de la region du village de Dzarmysh

Sample

number

Age - zone

species

MK 95

Middle Callovian

Coranatum zone

Kosmoceras (Zugokosmoceras) obductum (Buckman)

Kosmoceras (Zugokosmoceras) aff crassum Tintant

Grossouvria sp.

Flabellisphinctes villanyensis (Till)

MK 72

Top of lower Callovian

Calloviense zone and

subzone

Sigaloceras (S.) calloviense (Sowerby)

MK 73

Top of lower Callovian

Calloviense zone and

subzone

Sigaloceras (S.) calloviense (Sowerby)

MK 39bis

Top of lower Callovian

Proplanulites aff. capistratus Buckman

MK 42

Upper Callovian

Lamberti Zone

Quenstedtoceras sp.

Peltoceras sp.

Hecticoceras (Lunuloceras) cf. faurei Fallot

Hecticoceras (Lunuloceras) sp.

Kosmoceras annulatum Quenstedt

MK 42bis

Lower Oxfordian

Prolocardioceras cf. praecordatum (Douville)

MK 45

Lower Oxfordian

Protocardioceras sp.

MK 18

Top of lower Callovian

Proplanulites sp.

MK 19

Top of lower Callovian

Calloviense zone

Sigaloceras (S.) calloviense (Sowerby)

Sigaloceras (Gulielmina) quinqueplicatum Buckman

Proplanulites aff. koenigi (Sowerby)

MK 21

Top of lower Callovian

Calloviense zone

Sigaloceras (S.) calloviense (Sowerby)

Cadoceras sp.

Proplanulites cf. trifurcatus Buckman

Hectococeras (Lunuloceras) sp.

Choffatia sp.

litharenites to lithic arkoses (average composition Q = 32±11 ; F = 25±6 ; L = 43±11) (Fig. 10). Detrital

quartz is mostly monocrystalline (average C/Q = 9%); several grains display straight extinction and may

be ot volcanic origin. Alkali feldspars (locally perthitic orthoclase, subordinate microcline and

chessboard-albite) prevail over plagioclase (average P/F = 46%). Volcanic lithics are common and

argdy represented by felsitic and vitric types, with subordinate microlitic, fluidal and lathwork grains

(V/L = 85%); plagioclase-bearing to granophyric hypabissal grains and granitoid rock fragments are also

frequently recorded. Metasedimentary (slate, phyllite, quartzite, paragneiss) and sedimentary

MAURIZIO GAETANI ETAL.

(radiolarian chert, siltstone) rock fragments are both significant. Alterites are frequent in continental

settings: bivalves, benthic foraminifers, glaucony and silicatic peloids commonly characterize the

marine samples. Poikilotopic calcite or dolomite cements are widespread, but quartz or K-spar syntaxial

cements are also found. Secondary porosity is very significant in several samples.

FlG. 10.— Delrital modes for studied Jurassic and Cretaceous

samples are very close to Triassic samples (see Fig. 7;

polygons are one standard deviation each side of the

mean), but tend to be more dispersed. Sedimentary and

metasedimentary rock fragments are also present,

pointing to deposition in a collisional successor basin

linked with Eo-Cimmerian and Neo-Cimmerian suture

belts (Graham et at., 1993). Provenance fields are after

Dickinson (1985) and Marsagua & Ingersoll

(1992).

Fig. 10 .— Le conienu delrilique des echanlillons jurassiques el

cretaces sow lies pinches de ceux du Trias (voir jig. 7 ;

les polygones out line deviation standard de chaque cole

de I a principale). mais tendent d el re plus disperses. Des

fragments de roches sedimentaires el melasedi-

menlaires soul aussi presents, montrant un depot dans

un hassin en collision en liaison avec les ceinlures de

sulure eo-cinvnerienne el neo-ciminerienne (Graham el

ah, 1993). Zones de provenance d’apres DICKINSON

(1985) et Marsagua & Ingersoll (1992).

Chagabulak Formation

A mostly clayey unit, forming a recessive step

in the landscape, overlies the ferruginous crust.

Its basal part is often made by grey mudstones

and clayey marls in poorly defined beds of 20-

40 cm, for a total thickness of 4-5 m. The

mudstones may end abruptly or continue with

few lenticular layers followed by dark grey

splintery shales, that form the monotonous

remaining part of the unit, about 25-30 m-thick.

The sequence is topped by a ferruginous crust, a

few cm-thick.

AGE

The lowermost mudstone beds contain

ammonoids of the top of the late Callovian

(Lamberti Zone) (i.e. Quenstedoceras cf. prcie-

lamberti, Quenstedoceras sp., Pelloceras sp.,

Hecticoreas (Lunoloceras) cf. fan re i, Kosmoce-

ras annulatum, Euaspidoceras sp.). In the

middle-upper part of this lithozone, early

Oxfordian ammonoids, with Protocardioceras

cf. praecordatum were recovered. Coccoliths are

fairly abundant with Cyclagelosphaera wied-

manni, Stephanolithion hexum and S. bigoli

maximum marking the base of the Oxfordian, a

few tens of cm from the base of the mudstone

layer (Table 5).

In the overlying dark shales, nannofossils are

scarce, being dominated by the resistant

Watznaueria group, suggesting a generic

Oxfordian age (Table 4). Benthic foraminifers are

instead rather common.

Species identified are: Haplophragmoides sp., Textularia jurassica Guemb., Tristix tutkowskii Kapt.,

Nodosaria ex gr. oxforea Mjatl., Genizinita ex gr. crassata (Gerke), Ophthalmidium strumosum

(Guemb.), Quinqeloculina sp., Lagena ex. gr. laevis (Montagu), Lingulina ex gr. belorussica Mitjan.,

Dentalina oppeli Schw., Dentalina turgida Schw., Dentalina sp., Lenticulina ct. lumida (Mjatl.),

Lenticulina compressaeformis (Paalz.), Lenticulina comae Byk & Azbel, Lenticulina brueckmanni

(Mjatl.). Lenticulina hyalina (Mjatl.), Lenticulina aff. sumensis Pja. Lenticulina aff. russiensis (Mjatl.),

Lenticulina spp., Astacolus compressaeformis (Paalz.). Astacolus ectypa costata Cordey, Astacolus sp.,

Planularia colligata (Brueckm.), Planularia subcompressa (Schw.). Planularia contracta (Trq.),

Planularia spatulata (Wisn.), Planularia tricarinella Reuss, Planularia sp., Marginulinopsis aff.

procera (Kapt.), Saracenaria inclusa Schw., Saracenaria cornucopiae (Schw.), Falsopalmula

inaequilateralis (Terq.), Eoguttulina sp., Globuligerina sp., Marginulina batrakieformis Azbel,

Marginulina minuta Terquem, Citharina sokolovae (Mjatl.), Citharinella spatha (Lalicker), Epistomina

sp.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Table 4.— Distribution of calcareous nannofossils in the Upper Jurassic.

Tableau 4 — Repartition des calcaires nannofossiles ait Jurassique superieur.

(Si

MK78

MK77

MK76

MK75

MK74

MK73

MK71

MK70

MK69

(Si

5 8

.2 .55

0 0

3 13

0 0

C C

Nj Nj

I I

0 0

0 -tt

rn P

0 0

3 3

0 0

C C

FC MP

A ' M

C | M

FC t MP

FC| M |

4 s

•E 52

■O

-C

(Si

-3

(S)

—

(Si

c si

(Si

■n

-C

s I

8 g I

2 0 -C

F* I F

r r

b § o

c o

§ §

R FC

_* FC!

c c c

0 0 0

£ r r

Q a a

0 0 0 )

S co co

1 I

CL R

2 8

o m

, q_ci

F FC

MK38

MK37

MK36

MK35

MK34

MK33

MK32

MK31

MK30

MK29

MK28

M K2f

MK26

MK25

MK24

MK23

MK22

MK54

MK53

MKSP

I fti

MK51

MK50

MK49

I C

MK48

MK47

—

MK45

C H

MK44

MK43

M I

~F~

—

I F I R

—

;

——

—

——

— R

-i

;

RF ! PM

RF t PM T

E £

03 0

2 0

-Q 0 2

Sr © ■ S s -2

O -g 0 0

O Q

I c

O Q

' RF'

pm ; j_ r

PM 1 R

R PM

C P

CA | MP

CA _

CA CA CA

CA I CA I CA

_F_

_A | R | R

c^T

C ; F ; F

caTca!CA

R i FC

; f

T~R~

R ! R

—L

R A

f c

]. n conclusion, the Chagabulak Formation extends from the latest Callovian at its base to the

Oxfordian. It should be noted that no Kimmeridgian deposits are reported in the Gorny Mangyshlak and

only a few tens of metres of Kimmeridgian sediments were drilled in the Southern Mangyshlak

(Muromchev, 1968).

Environment

Open marine with steady clay input in a low-subsidence regime.

SEQ UENCE STRA TIGRA PH Y

The Chagabulak Formation represents the high-standing tract and the sequence is truncated at the top

by a non-depositional or erosional surface.

MAURIZIO GAETANI ET AL.

THE CRETACEOUS

The Cretaceous succession crops out extensively all around the Gorny Mangyshlak and is especially

well exposed on its northern slope. It was the object of several recent detailed studies (Kopaevich,

1989; LUPPOV et al, 1988; MARCINOWSKI et al., 1996; NAID1N et al, 1984,) and is presently under

further study by a team from Moscow University directed by L. F. KOPAEVICH and E. J. BARABOSHKIN.

The succession may reach 1000 m in thickness and may be subdivided into three parts, bottom to top.

— Three to four sandy to shaly sequences, rarely including shallow water carbonates, with low

subsidence rate. Berriasian-Barremian (part A).

— A complex pattern of shaly to sandy sequences in a higher subsidence regime, but also with many

non-sedimentation gaps in the upper part. Aptian-Turonian (part B).

— A uniform, whitish chalky sedimentation in open marine environment in a low subsidence pattern.

Coniacian to earliest Palaeocene (part C).

For logistic reasons, we had the opportunity to sample only a few sections and consequently we

provide only sparse data and conclusions on the Cretaceous stratigraphy and evolution. We will present

data on parts A and C. The upper Albian-Coniacian part was described exhaustively by MARCINOWSKI

et al. (1996). The ammonoids collected from the Semenoviceras horizon (late Albian) were illustrated

by CECCA (1997).

Dzhamansauran

(10 km East to Dzharmysh)

~] Sandstone

j Poorly cemented sand

Bioclastic sands

!• • •! Cross bedded coarser sandstone

ESS Calcilutitc

Marl

|~~1 Shale and siltite

ki&Hl Rastellum coquina

Borse

(8 km East to

v =,

Dzharmysh)

West to Dzharmysh

(road section)

CJj

•E

O’

(Si

- -9-

c Si

Fig. 11.— Lower Cretaceous sections measured on the north

side of East Karatau. Gorny Mangyshlak.

Fig. 11 .— Coupes levees dans le Cretace inferieur du cole nord

de l 'est Karatau.

Part A

A lithostratigraphic scheme has not yet been

published for the lower portion of this part,

probably due to the large lateral variability and

reduced thickness of this succession. Only the

upper red siltstones and shales were grouped into

the Kugusem Formation. A brief review fol¬

lows, according to the sequences we identified

(Fig. 11).

Sequence 1.— From a few km west of

Dzharmysh to 10 km east of the village, the

succession is as follow, bottom to top:

— extremely dense accumulation of oyster¬

like ( Rastellum ) building mounds up to 9 m

thick. At the top, a nannofossil assemblage

was found ( Watznaueria spp., W. barnesae,

W. britannica, Nannoconus spp. (both narrow-

and wide-canal forms), Nannoconus stein-

mannii minor, Zygodiscus spp., Zygodiscus

erect us. Cyclagelosphaera marge relii , C.

deflandrei, Micrantolithus hoschulzii, M.

obtusus, Biscutum constans and Lithraphidites

carniolensis (sample MK 137, section

Dzhamansauran);

— litharenites and poorly cemented sands, brown

to greenish, locally with coarse, high-angle

cross-bedding. Sparse brachiopods and bi¬

valves. Up to 15 m;

Source: MNHN, Paris

THF. MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

— bioclastic hybrid sandstones, rich in bivalves, especially oysters, and few ammonoids (Rvazanites

beds of LUPPOV et al., 1988). 2 to 5 m;

— whitish to light grey chalky limestones. 1-2 m thick.

The development of this sequence was analysed in detail in the monograph of LUPPOV et al. (1988),

who distinguished 5 types of possible successions.

AGE

According to LUPPOV et al. (1988) the upper part of the Berriasian, from the Neocosmoceras up to

Ryazinites ammonoid zones, is represented. The age of the nannofossil assemblage is Berriasian-

Valanginian, but the absence of latest Berriasian or younger markers restricts the sample to the

Berriasian. Consequently, the gap between the Rastellum Bank and the top of the Chagabulak Formation

includes Kimmeridgian, Tithonian and lower Berriasian, for a time span of at least 10-15 m.y.

Environment

The lithology suggests a shore-face environment with short-lived episodes of more open marine

conditions. The relative abundance of nannoconids and braarudosphaerids suggests deposition in a

marginal setting, with possible eutrophic conditions as inferred by the occurrence of Biscutum and

Zygodyscus. All nannofossil specimens are characterized by small size. This is peculiar to lagoonal

nannofloras from the modern oceans and the fossil record, suggesting a very restricted environment.

Sequence 2.— Yellowish to olive-green, poorly cemented sandstones with high-angle cross-

laminations and poorly defined bedding. They form a cliff about 20 m-bigh which is in turn overlain by

10 to 15 m of greyish to dark grey shales.

Age

According to the Samarkand Scheme (1977) this sequence represents the Valanginian. No

nannofossils were found in the shales.

Environment

The lower sandstone layer indicates a shore-face environment with coastal sands forming festooned

bars. The overlying shales should represent the deepening of the sequence.

Sequence 3.— Sequence 3 starts with a thin cross-laminated arenaceous bed 40 cm-thick (MK 148).

It contains fragments of Trigoniancean bivalves. It is followed by about 10 m of grey-green shales and

mails, in turn overlain by pinkish marls (3 m). This sequence is also capped by a cross-laminated

sandstone with ostreid fragments 1.8 m-thick (MK 154). The total thickness is about 15 m.

Age

According to the Samarkand Scheme, this sequence represents the lower Hauterivian. Samples

analysed tor coccoliths were negative.

Environment

Similar to sequence 2.

KUGUSEM FORMATION.— This sandy to shaly unit caps the first part of the Cretaceous succession. It

consists of a basal layer of grey, high angle cross-laminated sandstones, with current direction towards

WSW. followed by very fine sandstones, siltites and occasionally shales of red to pink colour. The top is

made ot pink siltites and grey fine sandstones with ripple-marks. This unit is cliff-forming and is several

tens of m-thick.

Age

According to the Samarkand Scheme (1977) this unit represents the upper Hauterivian and all but the

upper part of the Barremian. No new data are available.

MAURIZIO GAETANI ET AL

Environment

Coastal marine to continental alluvial plain in oxic conditions.

Composition of Lower Cretaceous arenites. — Very few sandstone samples were sufficiently

coarse to he counted (MK 148, MK 154, MK 155, MK 157). The arenites studied are fine-grained

feldspathic litharenites to lithic arkoses (average composition Q - 38±6 ; F = 24±8 ; L = 38±9) (Fig. 10).

Detrital quartz is mostly monocrystalline (average C/Q = 10%); several grains display straight extinction

or even bipyramidal outlines and may be of volcanic origin. Alkali feldspars (locally perthitic

orthoclase, subordinate microcline and chessboard-albite) prevail over plagioclase (average P/F= 42%).

Volcanic lithics are common and largely represented by felsitic and vitric types, with subordinate

mierolitic and lathwork grains (V/L = 83%); granophyric, myrmechitic and granitoid grains are

common. Metasedimentary (slate, greenschist, chloritoschist, phyllite) and sedimentary (chert, siltstone,

shale) rock fragments are both significant. Micas, zircon, and celadonite are frequently recorded.

Alterites and soil fragments characterize fluviatile samples; glaucony, silicate peloids, bivalves, benthic

foraminifers, ooids and peloids commonly occur in marine settings. Locally, poikilotopic calcite or

dolomite cements and late diagenetic replacements are widespread; quartz or K-spar syntaxial cements

also occur. Secondary porosity is significant in several samples.

PARTB

This part is often very poorly exposed, especially in its lower portion, where the steppe hides large

segments of the outcrops. Its base is transgressive with a few dm of hybrid siltstones and calcareous

siltites and locally, like NW of Shetpe, along the road to Akmysh, it covers the underlying Kugusem

formation with a gentle angular unconformity.

It may be subdivided roughly, bottom to top, as follows.

— black shale unit with thin siltitic layers and fine arenaceous nodules. Very faint interference ripples in

the thin arenaceous layers. > 100 m thick. Aptian.

— monotonous succession of shales and siltitic shales with more arenaceous intercalations coarsening

upwards. Very peculiar sandstone concretions m-sized, sometimes with high-angle cross-laminations.

Not less than 300 m, but thickness difficult to assess. The lower Albian section has been extensively

studied by SAVELIEV (1992). Aptian-? middle Albian.

— phosphatic sandstones, also forming m-thick concretions, alternating with shaly packages tens of m-

thick. The sedimentation rate seems to decrease upwards where several phosphatic horizons, very

useful tools for regional correlations (MARCINOWSKI et al., 1996) are present. Sedimentation gaps

are frequent in the Cenomanian-Turonian part, with the upper Turonian mostly represented by

condensed phosphatic horizons. Overall thickness up to 120 m. Upper Albian-Turonian.

The succession No. 3 was monographed in detail by MARCINOWSKI et al. (1996). We collected 35

samples for calcareous nannofossils and all resulted barren. A rich ammonoid fauna was found in the

sandy phosphatic concretions about 500 m northwest of the Akmysh Pioneer Camp and Spring (Fig. 1).

Above a first level with Semenoviceras mangyschlakensis (Saveliev), a very rich horizon of

phosphatized ammonoids and trigoniids is present. The ammonoids include Semenoviceras uhligi

(Semenov), S. litschkovi (Saveliev), S. pseudocoelonodosus (Semenov), S. michalskii (Semenov) and

indicate the S. litschkovi Zone of the upper Albian (= Semenovites michalskii Zone in MARCINOWSKI et

al., 1996), correlatable to the Dipoloceras cristatum Zone of Western Europe. Immediately above this

horizon, which is about 5 m thick, poorly exposed grey sands follow. A single specimen of

Cunningtoniceras aff. inerme (Pervinquiere) was collected, suggesting a middle Cenomanian age. These

specimens were described by Cecca (1997).

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Part C = "Chalk-like" Unit

.. J h f e Aktau ( ^h |te Mountains) characterize the landscape around the Gorny Mangyshlak with white

chtt forming chalk. In this unit, consisting of light grey marls and marly limestone rithmites and

extending up to the early Palaeocene (NAIDIN el at., 1984), we sampled two sections at Chirkala and

near Endikurgan (Figs 1 and 1 I), for foramimfers and nannofossils, which add new data to the paner of

MARCINOWK] et at. (1996) and NAIDIN et at. (1984). ^

Chirkala section.— The section was measured probably slightly east of the Shyrkala section of

Marcinowski et at. . (1996), to date the base of the "Chalk-like” unit (Fig. 11). A few samples were

also collected in the phosphatic horizons and yellowish quartzitic sands.

Calcareous nannofossils are common to abundant in samples MK 418 through 428. Preservation is

pool in the bottom sample and increases in quality upwards. The assemblages are characterized by

common to abundant Prediscosphaera spp., Watznaueria barnesae , Eiffellithus eximius , Eiffellithus

lumseiffel", Eprolithus floral is, Tranolithus phacetosus, Zygodiscus spp., Zygodiscus diplogrammus,

Zygodiscuserectus, Microrhabdulus decoratus, Lucianorhabdus maleformis, Amhuellerella octoradiata,

Cylindralithus sp., Cretarhabdus spp., Cribrospluierella ehrcnhergii and Manivitel/a pemmatoidea. A

tew nannocomds (N. ntulticadus, N. farinacciae, N. mi minis and cross sections of narrow-canal forms)

were observed in most samples.

Age

The occurrence of Lithastrinus septenarius in samples MK 418 through 428 indicate a Coniacian to

earliest Santonian age. A single specimen identified tentatively due to poor preservation as Reinhardtites

anthophorus was observed in sample MK 420 and indicates the base of the Santonian. Samples MK 424

through 428 contain common Micuta decussata which is indicative, along with L. septenarius of the

upper Coniacian-lowermost Santonian CC 14-15 zones of SlSSlNGH (1977). It should be noted that our

results suggest a younger age (i.e. Coniacian) for the top of the sands, instead of early Turanian as

indicated by Marcinowki et at. (1996).

Endikurgan section — The section was measured along the slope, west of the Endikurgan hamlet,

and a lew samples were collected in an isolated outcrop, directly below the main section" in the Hat

steppe to the SW.

The entire section lies within the "Chalk-like Unit" (Fig. 12).

Calcareous Nannofossils

The lowermost part of the section (samples MK 412 through 417) contains common to abundant,

moderately prescrycd nannofloras. The assemblages are characterized by common Micuta decussata and

tediscosphaera spp. along with frequent Lucianorhabdus cayeuxii, Lucianorhabdus maleformis,

7 alcuhtes obscurus, Eiffellithus eximius, Nannoconus spp., Nannoconus multicadus and Watznaueria

Hirnesae. Aspidolithus parcus parcus and Aspidolithus parcus constrictus as well as Ceratolithoides

aculeus were observed throughout the section. Quadrum sissinghii occurs in samples MK 413 and 414,

whereas Reinhardtites levis was found in samples MK 416 and 417. Such an assemblage, together with

of Quadrum trifidum, are indicative of the mid-Campanian CC 20-21 zones ofSlSSINGH

(1977) (Erba etal., 1995).

Calcareous nannofloras are common to abundant and poorly to moderately preserved in samples MK

300 through 411. Although both diversity and preservation slightly fluctuate, the assemblages are very

-similar in all samples. The most abundant taxa are: Prediscopshaera spp., Watznaueria barnesae,

Micuta decussata, Lucianorhabdus cayeuxii, Calculites obscurus and Cylindralithus serratus. Quadrum

gothicum, Cribrosphaerelta ehrenbergii, Reinhardtites levis, Aspidolithus parcus constrictus and

Microrhabdulus decoratus are always present and their abundance fluctuates from rare to frequent.

Eiffellithus eximius was observed only in the lower part of the section, from sample MK 300 through

MAURIZIO GAETANI ET AL.

MK353

MK352

MK351

MK350

MK349

MK348

MK347

MK346

MK345

MK344

MK343

MK342

MK341

MK340

MK339

MK338

MK337

MK336

MK335

MK334

MK333

MK332

MK331

MK330

MK329

MK328

MK327

MK326

MK325

MK324

MK323

MK322

MK321

MK320

MK319

MK318

MK317

MK316

MK315

MK314

MK313

MK312

MK311

MK310

MK309

MK308

MK307

MK306

MK305

MK304

MK303

MK302

MK301

MK 300

1 1 1

U-

a»

</>

—I

C/A

F/C

C/A

F/C

C/A

F/C

C/A

F/C

C/A

F/C

C/A

F/C

R/F

RTF

R/F

•e

R/F

c-;

R/F

l CL

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

fragmented

R/F

F/C C

F C

R/F R/F

MK416

MK415

MK414

MK413

MK412

MK417

MK424

MK423

MK421

MK428

MK420

MK427

MK425

R R

1 VR

R F/C A C/A F C C

F C R A F/C F/C

F F/C F/C F F

R C C F/C F C

C R C R C

C C F R F C

F C R C F R/F C

F cf/F

R R

cf/R

F F R

F cf/R R F/C R

R F F R

R R R cf/R

Source: MNHN. Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Table 5.— Distribution of planktonic foraminifers in the "Chalk-like unit".

Tableau 5 .— Repartition desforaminijerespianctoniques dans "Tunite crayeuse".

t/>

MK411

MK410

MK409

MK408

MK407

MK406

MK405

MK404

MK403

MK402

MK401

MK40O

MK399

MK398

MK397

MK396

MK395

MK394

MK393

MK392

& 8

■a -8 fi fi

<0 (0

| | |

1 I 1

■= = c c cf

1 I

G G

O 1

3 O

c -o

o —

O O

5 I

o g>

fi I

G G

a a

5 2

c ©

<t3 «o

a |

I s

? I

2232»i;S5§

GGCCGCGXa? II G

MK391

MK390

MK389

MK388

MK387

MK386

MK385

MK384

MK383

MK382

MK381

MK380

MK379

MK378

2 1

R 3

MK377

MK376

MK375

MK374

MK373

MK372

MK371

MK370

MK369

MK368

MK367

MK366

MK365

MK364

MK363

MK362

MK361

MK360

MK359

MK358

MK357

MK356

MK355

MK354

R/FF/C

, F

R/F 1

F C

F F/C

F C

F 1

F 2

1 3

2/cl

2 3

I 1

1/d 1

u. <

7 CC

i u

O 2

u. <

% O

2 u.

2 o

5 x

o. to

E <

e s

x .a o -

i- c y o

1 /cl 2

3 1

4/cl 2

1 1

2 1 3

R/F

2 1

2 I

1 1 1/cl

2 1

2 1 2

C C/A

2 1 2

Ir VR

VR AA

F/C C/A

C C/A

F/C C/A

F C/A

F/C C/A

C C/A

R C

R C/A

R/F C/A

F C/A

F/C C/A

C/A

F/C

Source: MNHN, Paris

MAURIZIO GAETANI ET AL

Fig. 12.— Upper Cretaceous sections measured on the northern side of Gorny Mangyshlak, with calcareous nannofossil and

foraminiferal ranges.

Fig. 12 .— Coupes levees dans le Cretace superieur de la partie nord du Gorny Mangyshlak, avec les repartitions des

nannofossiles calcaires et foraminiferes planctoniques.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

sample MK 342, whereas Quadrum trifidum was found for the first time in sample MK 354. This taxon

was consistently observed upward through sample MK 398, but not in the uppermost part of the section.

Only a single specimen of Quadrum trifidum was identified tentatively in the top sample MK 411, due

to extremely poor preservation.

Although never abundant, nannoconids ( Nannoconus multicadus , Nannoconus dauvillieri and cross

sections of narrow-canal forms) are present in the lower part of the section (samples MK 300 through

354), but are absent or extremely rare upwards. A few Nannoconus spp., N. multicadus and/V.

dauvillieri were observed in sample MK 378 which also contained a few specimens of Thoracosphaera

sp.

The lower part of the section is assigned to the mid-Campanian CC 20-21 zones of SlSSlNGH (1977).

The first occurrence of Quadrum trifidum in sample MK 354 indicates the base of the CC 22 Zone

(SlSSlNGH, 1977). The continuous range of this taxon up to sample MK 398 indicates the CC 22 and 23

zones and therefore place the Campanian/Maastrichtian boundary very close to sample MK 398. Both

Eiffellithus eximius and Tranolithus phacelosus are extremely rare and sporadic throughout the section

and therefore are not considered as stratigraphic markers in this study.

Foraminifers

A total of 1 17 samples from the Endikurgan section were investigated for planktonic foraminifers

(Table 5). They were separated in three fractions corresponding to mesh sizes of >250 gun, >150 pm and

>40 pm, respectively. Small-sized planktonic specimens dominate throughout the section. This is due to

the constant presence of the generally small-sized heterohelicids and globigerinelloidids. Both fractions

larger than 150 pm consist only of benthic foraminifers and are devoid of planktonic forms.

Consequently, the normally large-sized (> 250 pm) planktonic taxa with ornamentation (keels, costellae,

etc.) are represented only as small-sized or juvenile specimens. This fact made species identification

extremely difficult. In addition, the few species identified are recorded very discontinuously. Therefore,

age-diagnostic taxa are rare and their paucity resulted in generally poor biostratigraphic resolution.

The lower segment of the Endikurgan section yields a very poor planktonic foraminiferal

assemblages consisting of rare specimens of Heterohelix, mainly not identifiable at the species level (see

Table 6). Only single specimens of Heterohelix globulosa and Globigerinelloides asper could be

identified with certainty in one out of three of the six samples. The washed residues of this segment

yielded abundant, fairly well-preserved benthic foraminifers and abundant radiolarians.

In the lowermost part of the upper segment planktonic foraminifers increase slightly in abundance,

always in association with abundant benthic foraminifers and radiolarians. The heterohelicids are the

only planktonic component and H. globulosa is present constantly. No Globigerinelloides could be

identified in the lowermost 6 samples (MK 300 to MK 305). In the upper three samples of this interval

rare to few calcispheres are also recorded.

In the interval from MK 307 to MK 315, the washed residues contain few planktonic foraminifers

mainly belonging to Heterohelix (rare H. globulosa ), frequently associated with globigerinelloidids.

Peculiar to this interval is the poor preservation of the abundant benthic foraminifers, which are

commonly fragmented. Rare to few calcispheres and abundant radiolarians occur throughout the

interval.

In the overlying interval (MK 316 to MK 347) planktonic foraminifers become common, even

though the diversity remains very low. The planktonic faunas consist only of Heterohelix and

Globigerinelloides, rarely identified at the species level. The increase in abundance of planktonic

foraminifers coincides with a decrease in radiolarians from abundant to common. Benthic foraminifers

are abundant and fairly well preserved throughout the interval, while calcispheres, still rare to few in the

lower part ol the interval, increase slightly in abundance in the upper part.

A major change is observed beginning with sample MK 348. In this sample, planktonic foraminifers

become more diversified and rare keeled species such as Globotruncana ventricosa, Contusotruncana

plummerae and C. fornicata appear, in addition to the still common Heterohelix and few

Globigerinelloides. This increase in diversity among planktonic foraminifers coincides with a marked

increase in abundance of calcispheres, paralleled by a decrease in abundance of radiolarians and benthic

foraminifers.

MAURJZIO GAETANI ET AL.

Above this level, up to about sample MK 378, planktonic foraminifers tend to increase in diversity,

although the distribution of single species is discontinuous. Calcispheres continue to increase in

abundance, benthic foraminifers remain highly abundant, whereas only a few radiolarians remain.

All organic components from the remaining upper part of the section fluctuate in abundance, with

intervals that are very rich in calcispheres associated with rare but diversified planktonic foraminifers

alternating with intervals that contain slightly more common planktonic foraminifers and less abundant

calcispheres. The group of planktonic foraminifers affected most drastically are the heterohelicids,

which are rare overall, and occasionally confined to a single specimen of H. globulosa. Benthic

foraminifers show very little changes in abundance throughout the interval, whereas radiolarians become

progressively rare to absent.

Despite the very scattered record and distribution of planktonic foraminifers, three biozones could be

reliably identified (Erba el al., 1995):

— the Globotruncanella havanensis Zone, based on the presence of Heterohelix labellosa in sample MK

378, whose first appearance, according to NEDERBRAGT (1990), almost coincides with the base of

this zone;

— the Globotruncana aegyptiaca Zone, based on the presence of a single specimen of the nominal taxon

in sample MK 384;

— the Gansserina gansseri Zone, based on the appearance of Globotruncanella pschadae, which,

according to CARON (1985), is equated with the base of this zone. This occurrence in sample MK

392 is also supported by the evolutionary appearance of Abathomphalus intermedins slightly higher

in sample MK 398. In the absence of further biostratigraphic events, the G. gansseri Zone is extended

to the top of the Endikurgan section.

In addition, the occurrence of two specimens identified as Globotruncanita subspinosa in samples

MK 373 and MK 375 suggests that the Radotruncana calcarata Zone might be represented from sample

MK 373 to MK 377, below the G. havanensis Zone.

The remaining lower part of the section, including the lower segment, is remarkably poor in age-

diagnostic planktonic taxa. Based on its lower stratigraphic position and especially on calcareous

nannofossil data, this lower part is inferred to belong to the Globotruncana ventricosa Zone.

AGE

The biostratigraphy of planktonic foraminifers is in agreement with the calcareous nannofossil data.

The correlation between calcareous nannofossil and planktonic foraminiferal zones is reported in Fig. 12

showing that the inferred R. calcarata Zone falls within the CC22-CC23 nannofossil zones, suggesting

that its presence may be real. Finally, the position of the Campanian/Maastrichtian boundary, equated

with the CC23/CC24 nannofossil zonal boundary, is further supported by the appearance of A.

intermedius within the G. gansseri Zone.

On the basis of both calcareous nannofossil and planktonic foraminiferal data, we conclude that the

Endikurgan section spans the interval from the mid Campanian to the lower Maastrichtian for a duration

of about 10 m.y., and that sedimentation in this interval appears to be continuous.

Environment

The white chalk sedimentation indicates an open shelf environment under the wave base. The

abundance of small-sized foraminifers with heterohelicids in the lower part indicates an area influenced

strongly by upwelling. The frequency of short-duration gaps with short lateral extent and with cherty

horizons, especially in the Maastrichtian part (NAIDIN et al., 1984), suggests that the bottom was

extensively swept by currents.

CONCLUSION

Time available for field work was too short to produce a complete picture of the Mesozoic

stratigraphy of the Gorny Mangyshlak. Our conclusions are innovative in the following points.

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

Triassic

- The main features in a sequential scheme are reported in Fig. 13.

- The Tyururpa Group was extensively sampled, which resulted in the first finding of conodonts and

ofconcdonte ° parUcu ^ the Donkranites Beds ma y be assigned to the early Spathian on the basis

- Palynomorphs at the base of the Akmysh Formation may delimit the age of this unit to the Carnian

Consequently, the regional paraconformity at its base is positioned around the Ladinian/Carnian

boundary.

- Most important is the palaeogeographic problem posed by the petrographic analysis of the Triassic

sandstones of Mangyshlak. They consist of volcanic detritus, possibly derived from an active

magmatic arc related to the northward subduction of the Palaeo-Tethys (Sengor et al. 1988' Baud

el al., 1991; DERCOURT et al., 1993). Their petrographic signature and time trends, peculiar when

compared to typical arc-derived suites, broadly compare with volcaniclastics found in modern .strike-

slip settings and with other Triassic clastic wedges also related to final consumption of the Palaeo-

Tethys (e.g., GARZANTI, 1985). Alternatively, detrital modes may indicate erosion of an arc orogen

and deposition m a retroarc foreland basin (MCBRIDE et al., 1975; Dickinson, 1985) or even

provenance from a relict Palaeozoic arc terrane and accumulation in a “Chinese-type” collisional

successor basin (GRAHAM et al, 1993) (Fig. 13). Climate was probably semiarid with a humid

season (e.g HENDRIX et al., 1992; GARZANTI et al., 1995; Mum & WEISSERT, 1995), and became

progressively subhumid in the Late Triassic, when coal was deposited in nearby areas (Ruttner et

al., 1991; Zhidovinov, 1994). v

Age

Group/Fm.

Litholoev FoqqiI rnntpnt

environment

Silty to fine sandy flat

Sequences

Shair

A *- X I

Rare shell lags with

Submerged muddy flat with rare

—

bivalves and gastropods

carbonate episodes

m.f.s.

V..V.1

Silty to very line sandy flat

Akmysh

Shell lags

Submerged muddy

---

with bivalves and gastropods

Palvnomnmh'i

fan with occasional storm deposits

Marine digression

m.f.s.

1-£ « n „

Alluvial plain with point bar channels

' 'Submerged silty fan with

Karaduan

a Karadzhatick

□ Stacheites Beds

. -episodic shell lags

m.f.s.

Z) Columbites Beds

Submerged muddy ramp with

1°

~1 Tirolites s.l. Beds

episodic wackestone lenses

lartaly Fm.

M M A

-1

^ Donkranites Beds

m.f.s.

Alluvial muddy plain with channels

Dolnapa

tilled by fine grained litharenites

and felsic litharenites

•—i

Otpan

r 200 m

Alluvial muddy plain with rare

*• A A ^

L 0

coarser sandy spells.

Fig. 13. Main leatures of the Triassic formations in Karatauchik and West Karatau of Gomy Mangyshlak.

^ ^'77 F' incipales caracteristiques des formations du Trias dans les coupes de Karatauchik et ouest Karatau. Gomy

Mangyshlak.

MAURIZIO GAETANI ET AL.

Jurassic

The analysis of the Jurassic succession brought to attention the need for a revision of its lower part,

below the Callovian transgression. Sporomorphs and especially dinocysts indicate the possible presence

of important pre-Callovian gaps and a very detailed analysis is needed to have a more accurate picture of

the mostly continental to marginal successions of the Middle Jurassic.

Cretaceous

Results are sparse. The age refinement in the Lower Cretaceous was limited, because of the poor or

mostly absent calcareous nannofossils. Additional data on the Semenoviceras horizon are discussed by

CECCA (1997).

The first findings of calcareous nannofossils and a list of planktonic foraminifers for the "chalk-like

unit" in the Coniacian-Maastrichtian interval are presented. Sedimentation rate slightly increased in the

mid Campanian-Maastrichtian part, compared to the basal part, where frequent condensations occurred,

like the one described by Marcinowski et al. (1996) for the Cenomanian-Turonian interval.

Also for this part, new and intriguing is the hypothesis about of the provenance of Middle Jurassic

and Lower Cretaceous sandstones. Despite the limited number of sufficiently coarse arenites available

tor counting, the Middle Jurassic and Lower Cretaceous sandstones of Mangyshlak display an almost

identical petrographic composition. Detritus largely derives from volcanic rocks, with significant

contribution from plutonic, hypoabissal, metasedimentary and sedimentary rocks. Detrital modes plot

between the "Recycled Orogen" and "Dissected Magmatic Arc" provenance fields (Fig. 13; DICKINSON

& SUCZF.K, 1979; Dickinson, 1985), suggesting a collisional successor basin setting (Graham et al.,

1993). The pronounced volcanic character of these siliciclastics is not a function of contemporaneous

arc volcanism, but rather resulted from the erosion of relict arc assemblages of Paleozoic to Triassic age.

Detritus was derived from an orogenic belt including arc volcanics and volcaniclastics, uplifted by The

latest Triassic collision between the Iranian Block and the southern active margin of the Turan Block.

Volcanic rock fragments are still abundant (particularly in finer-grained sandstones), but less

homogeneous than in the Triassic succession, with the occurrence of mafic (basalts) to felsic (rhyolites,

rhyodacites) grain types. Low quartz, content and the scarcity of sedimentary rock fragments indicate

that most detritus was not derived from a thin-skinned foreland fold-thrust belt involving a thick passive

margin sedimentary succession. Rather, occurrence of radiolarian chert and a few greenschist to

chloritoschist lithics suggests contributions from Eo-Cimmerian to Neo-Cimmerian suture belts, as for

the roughly coeval siliciclastics found in central Asia (GAETANI et al., 1993). Granitoid detritus, as well

as abundance of feldspar grains and low P/F ratio, document the erosion of basement rocks at the core of

the orogen soon after the Eo-Cimmerian collision (GARZANTI et al., 1996).

The overall conclusion concerning the petrographic analysis is that changes in detrital mineralogy are

minor throughout the Mesozoic (Fig. 14). In particular, composition of Middle Jurassic and Lower

Cretaceous units is virtually identical, indicating that if the Eo-Cimmerian orogenic event was surely

significant, the Neo-Cimmerian collision probably simply rejuvenated sources of detritus already active

in the Jurassic.

We may summarize the sedimentary and geodynamic evolution of the Mangyshlak in the following

scheme (Table 6).

Source: MNHN. Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

different ,1 ?' oul '! es d " Mangyshlak sont tons donum’s par des detritiques volcaniques et ne soul virtttellemeni pas

rnlli finn J: ■ volcanoplutomques circum-pacifiques avec des repons standards. Une origine de bassin en

T TrZ n lndl ‘l u i e -. "" moms pour les unites du Jurassique el dtt Cretace (voir texte pour la discussion).

Trin «■ , un J e * ec f an " llon J du Tnas hferteur tncluent les formations de Otpan. Dolnapa et Tyururpa : Trias moyen.

mas super,eur basal et tnas super,eur correspondent a,a formations de Karaduan. Akmvsh et Shair respectivement) ■

K fh‘Zn‘!,T ) I Cre . tac , e •' Q , : . c l“ anz (Q ,n ■' monocristaUin ; Qp : polycristallin) ; F feldspaths (P : plagioclase :

Iv-vnlfn alcal,ns ’ incluant I albite enechiquter) ; L : fragments de rocltes aphaniliques. (Lm : metamorphique ;

' 1 o'tanique ; Ls : sedimentatre). Zones de provenance d apres DICKINSON (/ 985).

MAURIZIO GAETANI ETAL.

Table 6.— Sedimentary and geodynamic evolution of the Mangyshlak.

Tableau 6 .— Evolution sedimentaire et geodynamique du Mangyshlak.

Ages

Environment

Palaeocene - Coniacian

Outer shelf mostly feeded by

planktonic rain

Turonian - Aptian

Muddy outer submarine fan, with

sandy spells and phosphatic con¬

densation horizons

Barremian - Berriasian

Shallow water terrigenous sequen¬

ces with glauconitic horizons,

ending with regional emersion in

the Barremian

Oxfordian - Callovian

Bathonian - Aalenian

Muddy outer shelf with non

depositional surfaces, enriched in

iron

Coastal plains and marshes with

coal seams, locally ingressed by

marginal sea

Norian - Carnian

Terrigenous internal shelf with

restricted ponds. Shelly tempesti-

tic lags

Middle Triassic-

Olenekian

Marine to alluvial volcaniclastic

fan with several sequences.

Deepest water in the Olenekian

Induan

Alluvial volcaniclastic fan

? Upper Permian deposits ?

Geodynamic setting

Stable continental shelf with low

subsidence rate

Continental shelf with fairly

large fine terrigenous input and

high subsidence, decreasing

upwards

Regional unconformity. End of

the Neo-Cimmerian move¬

ments

Continental shelf with low-

subsidence rate. Gentle epiroge-

nic movements

Regional unconformity linked

to the Neo-Cimmerian events

Gentle sea-level rise in a low

subsidence regime

Low subsidence rates

Major regional unconformity.

Folding due to the propagation

of the Eo-Cimmerian events.

Evolute pedogenesis

Partially submerged fan in a

back-arc basin setting.

Regional paraconformity

Back-arc basin setting

Source: MNHN, Paris

THE MESOZOIC OF THE MANGYSHLAK (WEST KAZAKHSTAN)

ACKNOWLEDGMENTS

The authors are indebted tor field help and assistance to N. LYBERIS and J T POLi (Paris) H

Yousufokaev, V.L TROITSKY and Y. Zahid (Tashkent). M. Balini and V.A. Gavrilova worked out

the Triassic ammonoids, V. J. Vuks the Triassic and Jurassic foraminifers, E. Garzanti the sandstone

petrography, A. NlCORA the conodonts, E. ERBA the nannoplankton, E. Cariou the Jurassic ammonites

K CECCA the Cretaceous ammonites, I. Premoli Silva and M. R. Petrizzo the Cretaceous

foraminifers, S. ClRlLLl the palynomorphs and R. Bucefalo Palliani the dinocysts M Gaetani

assembled a 1 these data and prepared the final version of the paper. Financial support by the Peri-Tethvs

Program and by the Italian CNR, grant No. 95/00390/05 to M. Gaetani

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Palynological Conference, Lucknow, 1976-1977. Vol. 2. Birbal Sahni Institute. Lucknow: 281-287.

Volkheimer, W. & QuaTTROCCHIO, M. E., 1981.— Distribution estratigrafica de los palinomorfos jurasicos y cretacicos en la

faja andina y areas adjacentes de America del sur Austral con especial eonsideracion de la Cuenca Neuquina. Cuencas

sedimentarias del Jurasico y Cretacico de America del Sur, 2: 407-444.

Volozh, Yu. a., Antipov. M.P.. Lipatova V.V., Voznesensky, A.I., Poliansky, B.V. & Shlezinger, A.Ye., submitted.—

The seismostratigraphy of the Scythian and South-west Turanian Plates. Geodiversitas.

Warrington,G., 1996.— Triassic spores and pollens. In: J. Jansonius & D.C. McGregor (eds). Palynology: principles and

applications. American Association Stratigraphy Palynology Foundation, 2: 755-766.

Zhidovinov, S.N.. 1994.— Paleogeography and conditions of Triassic formations in the territory of the Pricaspian Region.

Stratigraphy and Geological Correlations, 2/3: 51-66 (in Russian).

Source: MNHN, Paris

Development and deformation of a Mesozoic basin

adjacent to the Teisseyre-Tornquist Zone:

The Holy Cross Mountains (Poland)

Juliette Lam. ARCHE Jolanta Sw/DROWSKA < 21 , Frangoise BERGERAT' 11 ,

Maciej Hakenberg 121 , Jean-Louis Mansy 1 - 11 , Josef Wieczorek

Ewa STUPNICKA 151 & Thierry DUMONT 161

Departement de Geotectonique, CNRS ESA 7072, Universite Pierre e( Marie Curie

T25-26, E.l, case 129. 4 place Jussieu, F-75252 Paris Cedex 05, France

Institute of Geological Sciences, Polish Academy of Sciences (PAN)

Twarda 51/55, 00-818 Warszawa, Poland

' Laboratoire de sedimentologie et geodynamique, CNRS UR A 719. Universite Lille 1

Cite Scientiftque, F-59655 Villeneuve d’Ascq, France

141 Geotermia Podhalanska, ul. Szmony 17a, 34500 Zakopane. Poland

University of Warszawa, Department of Geology. Zwirki i Wigury 93, 02-089 Warszawa, Poland

161 CNRS UPRES-A 5025, Universite Joseph Fourier, rue Maurice Gignoux, F-38031 Grenoble Cedex, France

ABSTRACT

Pr ™ k W_SE st " ckmg Te,sse y re -Tcrnquist Zone marks the contact between the Palaeozoic west European platform and the

i bnan east European craton. It developped during the Palaeozoic, and was repeatedly reactivated during the Mesozoic

;r P nl en0 p°, IC , l "? eS -i, Under extensional (Polish Trough) and compressional (Polish Swell) tectonic regimes. The NW-SE

trenaing Polish Swell is superimposed on the Teisseyre-Tornquist Zone. The Polish Swell crops out'in the Holy Cross

~' nS ’- whbre wc investigated its structural evolution. From Late Permian to Late Cretaceous times, the tectonic regime

snh, I MOna ' C ,? ntr 0 r, mg lhe basm developement and synchronous filling. In the northern part of the Holy Cross Mountains

svnsprhmm ! llaps r 1 , aIe Fe ™ a " toEate Jurassic > retrace the extensional basin subsidence and emphasize the role of two main

^nsedimentary Uults. the WNW-ESE trending Holy Cross fault, and the NW-SE trending Nowe Miasto-Ilza fault that parallels

IV,mhT eyr fc i q -S! ISI Z ° ne ' From Late Permian 10 Lale Jurassic, the basin development occurred in three stages: a) Late

ho inHin T ,.- y Tnass ! c ’ , b) Earl >' Jurassic, c) Late Jurassic. During the two first phases major activity along the basin

ndin c taults is recorded whith the main subsidence axis trending NW-SE. In this zone, a set of NW-SE trending faults gave

T t n J- SwiDftowsKA. j.. Bergerat, F„ Hakenberg. M„ Mansy, J. L.. Wieczorek. J.. Stupnicka. E. & Dumont,

Monnoin77 d i Ve .pP meat anc * deformation ot a Mesozoic basin adjacent to the Teisseyre-Tornquist Zone: The Holy Cross

nh,f!n i;' i a o ) ' "■ S - CRAS 0d'N-Soi-EAU & E. Barrier (eds), Peri-Tethys Memoir 4: epicratonic basins of Peri-Tethyan

ptattomis, Mem. Mux. nam. Hixi. nat.. 179 : 75-92. Paris ISBN : 2-85653-518-4.

Source: MNHN, Paris

JULIETTE LAM ARCHE ET AL.

rise to the development of horsts and grabens during the Middle and Late Triassic. Activity along the Holy Cross fault varies:

important during the first stages, i, decreases to become null during the Late Jurassic stage so that the subsidence appears

homogenous Sedimentary dykes, filled with Late Pcrmian-Early Triassic sediments, suggest a N-S compressional and E-W

exten^onanectonic'regi'.ne at that time. Laramide shortening (Latest Cretaceous and Palaeogene) gave rtse to basin inversion.

P-ilaeostress computation from fault data sets indicate NE-SW compression, perpendicular to the Teisseyre-Tornquist Zone.

Micro-structures (conjugate strike-slip and reverse faults, stylolites, joints) are compatible with hrge-sca!^ s mctures (uplifting

of Holv Cross Mountains NW-SE fold axes). Detailed structural analyses reveal a complex tectonic evolution. The folds are

SediH narrow zone along the SW border of the Holy Cross Mountains (NW-SE fold axes) a.tibuted to reactivation ot

Triassic NW-SE trending basement fault, and in the northwestern prolongation of the Holy Cross fault (Radomsko Elevation),

where sinistral reactivation of the Holy Cross fault gave rise to the developpment of en echelon folds.

RESUME

Mise en place et deformation d'un bassin sedimentaire adjacent a la Zone Teisseyre-Tornquist : les Montagnes

Sainte Croix (Pologne).

S iinte Croix des cartes de subsidence du Permien superieur au Jurassique superieur illustrent le developpement du bassin,

e“rot «apes 5 a“pe„*n auperiau, - Triaf ipfenaar, b) au mferieur e. c) =S

nines revelent I’activite synsediinentaire de deux failles: la faille Sainte Croix de direction WNW-ESE et la taillc Nowe

Miasto-Ilza de direction WNW-ESE. parallcle a la Zone Teisseyre-Tornquist. L’activite de la faille Sainte Croix est lmportante

lors de la premiere etape puis decroit jusqu'a I’inactivite durant la troisieme etape. Sur le terrain, les indicateurs de 1 extension

dans le bassin sont des f.Ions sedimentaires a remplissage de Permien superieur - Trias

W et compression N-S Le bassin est ensuite inverse lors d un racourcissement NE-SW determine pai les calcuis ae paieo

contraintes P et d'age laramien (Cretace superieur - Paleogene). Cette direction NE-SW mdiquee par es mic ro-structu rest tail le s

inverses et decrochantes, stylolithes, joints) mesurees dans les roches mdsozoiques, est cohetente avec les deformations <

grande echelle du bassin (failles inverses et plis NW-SE). L’etude structurale de detail montre que les micro-structures sont

anterieures au plissement a grande echeile. Dans la couverture mesozoique, les plis sont localises. Dans une zone etroite

orientee NW-SE sur la bordurc sud des Montagnes Sainte Croix, les pits d'axes NW-SE sont attnbues a la reactivation d une

faille d'age triasique dans le substratum paleozoi'que. Dans le prolongement NW des Montagnes ^JJcrotx

Radomsko), des plis en echelon, dans la couverture mesozoique, sont attnbues a la reactivation senestre de la faille Sainte Croix

dans le substratum paleozoi'que.

OVERVIEW

The Teisseyre-Tornquist Zone (TTZ) makes the boundary between the Precambnan east European

platform (Russian Platform on Fig. 1) and the Phanerozoic west European platform which was affected

by the Caledonian, Variscan and Alpine (Alps, Carpathians on Fig. 1) orogens. The Moho discontinuity

is located at about 43-45 km below the east European Platform, deepens to 50-55 km below the 11Z anti

shallows to 30-35 km under the west European platform (GUTERCH et al., 1986). The TTZ trends NW-

SE, and extends from the Baltic Sea in the North (Poland) to the Black Sea in the South (Dobrogea in

Romania) (Fig. 1). In its central part (Ukraine), the TTZ is concealed beneath the Carpathian nappes.

The TTZ is revealed in Dobrogea, where Palaeozoic and Mesozoic rocks crop out. There, the

Peceneaga-Camena fault is the main element of the TTZ, reactivated as a reverse fault during the

Palaeogene (HlPPOLYTE et al., 1996). In Poland, the TTZ is covered by the Late Permian - Mesozoic

Polish sedimentary basin (“Polish Trough”) which was inverted during the Palaeocene and now forms

the so called “Polish Swell". This structure crops out in the Holy Cross Mountains where a nearly

complete sequence of Palaeozoic and Mesozoic strata is exposed (Fig. 2).

The Polish Trough developed during the Mesozoic times, superimposed to the TTZ. Therefore this

crustal discontinuity appears to have controlled the location and development ol the Polish Trough.

Subsequently, Laramide compressional intraplate tectonics were responsible for the inversion ot the

basin. Our objective was to gain a better understanding of the effect of the TTZ and other major ancient

structures on the development and deformation of the Polish Trough.

Source: MNHN. Paris

MESOZOIC DEVELOPMENT AND DEFORMATION OF THE HOLY CROSS MOUNTAINS (POLAND)

Fig. I.— Main structural units of central Europe showing the Teisseyre-Tornquist Zone (modified after Roure el al., 1996;

Kolarowa & Roth, 1977; Ksiazkiewicz el al., 1977; Ziegler, 1987. 1990; Poprawa & Nemcok, 1988-1989;

OSZCZYPKO& Slaczka. 1989; Zytko el al, 1989).

Fig. /.— Principales unites structurales de / ’Europe cenlra/e montrant la Zone Teisseyre-Tornquist (modifie d'apres RoURE et

al., 1996 ; Kolarowa & Roth. 1977 ; Ksiazkiewicz el al., 1977 ; Ziegler. 1987. 1990 ; Poprawa & Nemcok. 1988-

1989; Oszczypko & Slaczka. 1989; Zytko et al., 1989).

Apart from the Dobrogea in Romania, the Holy Cross Mountains of southern Poland are the only

place where the Permian and later structural and stratigraphic evolution of the TTZ can be studied in

outcrops. In the Holy Cross Mountains, rocks ranging in age from Cambrian to Miocene are exposed.

Sediments were almost continuous from Permian to Late Cretaceous, resting unconformably on

deformed Palaeozoic series. After the Laramide event, the Holy Cross Mountains were partly covered by

Miocene sediments. This exceptional area allows the acquisition of palaeostress indicators, in order to

analyse the relationship between the Palaeozoic and the Meso-Cenozoic structures and the importance of

Source:

JULIETTE LAMARCHE ETAL.

tectonic inheritance. As main tools we applied quantitative subsidence analyses and palaeostress

reconstructions, in addition to classical structural work.

RADOM

OPOLE

OMfSA

CARPATHIANS

TERTIARY

CRETACEOUS

JURASSIC

TRIASSIC

PERMIAN

CARBONIFEROUS

UPPER PALEOZOIC

LOWER PALEOZOIC

Fig. 2.— Geological map of southern Poland (modified from the geological map of Poland, scale 1:1 000 000. 1972). LB:

Lysogory Block; KB: Kielce Block.

Fig. 2.— Carte geologique du sud de la Pologne (modifie d'apres la carte geologique de la Pologne d Vechelle 1:1 000 000.

1972). LB : bloc de Lysogory : KB : bloc de Kielce.

PALAEOZOIC BASEMENT OF THE HOLY CROSS MOUNTAINS

The Holy Cross Mountains are located in the foreland of the Variscan orogen of western Europe and

adjacent to the southwestern margin of the Precambrian east European craton (Pozaryski &

KARNKOWSKI, 1992). The Palaeozoic part of the Holy Cross Mountains is composed of two blocks, the

Kielce block and Lysogory block, which are separated by the WNW-ESE striking Holy Cross fault

(Fig. 2), trending oblique to the TTZ (CZARNOCK1, 1957; GUTERCH et al ., 1976).

The Lysogory block to the North (LB on Fig. 2) has been interpreted as (1) an epicratonic element of

the East European Platform (TOMCZYK, 1988; MlZERSKl, 1995); (2) a Caledonian terrain (Lysogory

terrain, POZARYSKI & TOMCZYK, 1993); (3) the area of main Caledonian folding (DADLEZ el al.. 1994);

(4) an area of Variscan foreland folding (CZARNOCKI, 1957). The Kielce block (KB on Fig. 2) to the

Source: MNHN, Paris

MESOZOIC DEVELOPMENT AND DEFORMATION OF THE HOLY CROSS MOUNTAINS (POLAND) 79

South is considered to form a part of the Malopolska Massif (Fig. 1) (Tomczyk. 1988), belonging to the

Cadomia, a collage of Variscan suspect terrane (Bf.rthelsen, 1992).

The two blocks differing in their tectonic, stratigraphic and lithologic characters (MlZERSKI 1988)

were distant from each other during the Early Palaeozoic (STUPNICKA, 1992). They came close together

during the Variscan times (LEWANDOWSKI, 1993). Palaeomagnetic data from Lysogory and Kielce

blocks show their relative rotation with respect to each other and both with Baltica in a dextral wrench

regime (60° anticlockwise rotation of the south Holy Cross Mountains, Lewandowski 1993) The

Malopolska Massif was probably a sliver of Baltica detached from Crimea - Dobrogea region and

transfered along a dextral truncated margin of the Old Red Continent (LEWANDOWSKI, 1994). The Holy

Cross fault might be a remnant fragment of the former truncated margin of Baltica (Lewandowski

1993). The Variscan tectonics resulted in intensive folding with cleavage and affected both the Lysogory

and Kielce blocks. The Permo-Carboniferous dextral wrench faulting known in western and central

Europe (ZIEGLER, 1990) is not obvious in the Holy Cross Mountains and will be discussed later (cf.

section. Micro-structural data). This polyphased deformation results in a complex Palaeozoic basement

over which the Permo-Mesozoic rocks lie unconformably.

DEVELOPMENT OF THE HOLY CROSS PART OF THE POLISH TROUGH-

THE PERMIAN TO CRETACEOUS TIMES

From Late Permian onward till the end of the Cretaceous, the Polish Trough sedimentary basin

subsided on top of the TTZ. Its development is partly related to the intrusion of mantle material into the

lower crust and its densification, and partly to crustal extension and thinning of the lithosphere (DADLEZ

et ai, 1995). In an effort to reconstruct the evolution of the southern part of the Polish Trough, we

constructed subsidence rate maps from boreholes back stripped data (Fig. 3) (Hakenberg &

Swidrowska, 1997). The mapped area covered the northern part of the present Holy Cross Mountains

and part of the Warszawa-Lublin Syncline. The studied period ranges from Late Permian to Late

Jurassic times. The analysis of the Cretaceous period is in progress.

Subsidence and fault pattern

Biostratigraphic data, facies patterns, depositional environments and sediment thickness were the

basis for the reconstruction of palaeogeographic and palaeotectonic conditions controlling the basin

development from the Late Permian to Late Jurassic. The Late Permian to Late Jurassic sediments,

dominated by elastics, reached a thickness of 4.5 km, in the part of the basin that was addressed by our

study.

Deep faults controlling the subsidence are associated with zones of great thickness gradients

approximately paralleling the presumed basin margins. A comparison between facies and isopachs

patterns was an additional factor in our analysis of the tectonic subsidence and the identification of

synsedimentary faulting. The coincidence of lithofacies boundaries with zones of high subsidence rates

was taken as a strong argument for synsedimentary faulting.

The basin subsidence history based on subsidence rates derived from preserved sediments

accumulation, is presented on 7 maps (Fig. 3). The isolines values were obtained by dividing sediment

thicknesses, corrected for effects of compaction, by the duration of respective time interval, using the

ODIN & Odin time scale (1990). The two main bounding faults, defining the margins of the Holy Cross

segment of the Polish Trough, during Late Permian to Middle Jurassic times are the Nowe Miasto-Ilza

lault and the Holy Cross fault (NMIF and HCF). The first one trends NW-SE, parallel to the Teisseyre-

Tornquist Zone, whereas the second trends WNW-ESE. The HCF is a pre-Permian basement

discontinuity; the Nowe Miasto-Ilza fault may have originated later (CZARNOCKI, 1957; KOTANSKI &

Milaczewski. 1977). In the Late Permian to the Late Jurassic basin evolution, 4 stages are recognized

(Hakenberg & Swidrowska. 1997):

JULIETTE LAMARCHF. ET AL.

_„ _Svnsedimentary fault with isolines of subsidence rate,

K^d area without sedimentation decreasing throw j/ nVMy and control point map

Curve of average subsidence on the cross-

section along Kielce-Radom line

2250

250

500

1000

1250

Fig. 3._Maps of iso-subsidence lines for Late Permian to the Late Jurassic times (A to G) in the northern area of the Holy

Cross Mountains and a part of the Warszawa-Lublin Syncline and curve of average subsidence on the Kielce-Radom

cross section (after HakenbergA SnvidrOwska. 1997). 1 - la - lb: Nowe Miasto-Grojec fault zone; 2: Nowe Miasto-

Hza fault (NMIF); 3: Holy Cross fault (HCF). G: Grojec, NM: Nowe Miasto, RM: Rawa Mazowiecka. J: Ilza. PI: Early

Permian. P2: Late Permian. Tl: Early Triassic. T2: Middle Triassic. T3: Late Triassic. Jl: Early Jurassic. J2: Middle

Jurassic, Jo+k: Oxfordian and Kimmeridgian.

Fig. 3.— Canes des courbes d'iso-subsidence du Permien superieur au Jurassique superieur (A d G) au nord des Montagues

Sainte Croix et dans line partie du synclinal Varsovie-Lublin ; et courbe de subsidence moyenne le long de la coupe

Kielce-Radom (Hakenbf.RG & Swidrowska. 1997). I - la - lb : zone faillee de Nowe Miasto-Grojec ; 2 . faille Nowe

Miasto-llza (NMIF) ; 3 : Faille Sainte Croix (HCF) ; G : Grojec ; NM : Nowe Miasto ; RM : Rawa Mazowiecka ; J :

Ilza : PI : Permien inferieur. P2 : Permien superieur. T I : Trias inferieur, T2 : Trias moyen. T3 : Trias superieur. Jl :

Jurassique inferieur, J2 : Jurassic moyen. Jo+k : Oxfordien et Kimmeridgien.

THE Late PERMIAN AND Early TRIASSIC basin subsidence was closely controlled by the high activity

along the basin border faults (Fig. 3 A-B). The asymmetry of the Zechstein basin fill reflects the

geometry of two half grabens. In the south, a narrow half graben is located on the northern side of the

HCF. To the NW, a second half graben with opposite polarity is controlled by activity along the NW-SE

trending Nowe Miasto-llza fault/The two half grabens are limited by an accommodation zone transverse

to the basin axis (Nowe Miasto-Grojec zone, n° 1, la,b in Fig. 3 A-B). This zone coincides with a

decrease in evaporite content of the Zechstein succession toward the SE of the Pilica river line

(MORAWSKA, 1992). The polarity of rifted basins often changes where a rift crosses preexisting

dislocation zones (Colletta et al., 1988; MlLANl & Davison, 1988; ROSENDAHL et al., 1992; Ring,

1994); this appears to apply for the studied area in which there is evidence for Carboniferous activity

along the Grojec fault (Zelichowski et al., 1983). As main subsidence axes display a Z-shape, the

established fault pattern ressembles that of a convergent accommodation zone (terminology after

MORLEY et al., 1990).

During the Early Triassic, the two main bounding faults formed an overlapping set. Two half grabens

of opposite polarities, filled by lacustrine-continental sediments, dip away from each other (Fig. 3 B). At

the same time, an interference accommodation zone developed (terminology after ROSENDAHL et al..

Source: MNHN. Paris

MESOZOIC DEVELOPMENT AND DEFORMATION OF THE HOLY CROSS MOUNTAINS (POLAND) 8 1

1992), expressed in the central part of the basin by a ridge with relatively smal subsidence rates. When

rifting was initiated, two opposite low-angle detachments may have developed simultaneously

(BOSWORTH, 1985). Therefore it is possible that, at that time, a relative symmetry of the basin was

maintained. The most important characteristic of the Early Triassic basin is a high subsidence rate (550

m/Ma).

During the Middle and Late Triassic the two bounding faults were still active (Fig. 3 C-D),

although the subsidence rates decreased more than ten times. A few trough-parallel faults appeared

inside the basin. They delineate two subsident domains and a central horst. An interference

accommodation zone developed, limited by longitudinal faults (2b, 3a, b on Fig. 3 C.D). Such structures

dominate where the extension is relatively weak (Moustafa, 1996). Tilted fault blocks have been

described in many extensional basins (Colletta et al., 1988; YIELDING, 1990; Westaway &

Kusznir, 1993; Roberts & Yielding, 1995). The uppermost part of the central horst, was eroded

during the Late Triassic (big. 3 D). The erosional areas of Middle Triassic sediments does not coincide

with those of Upper Triassic, suggesting two separate deformation phases during the Late Triassic (the

early Cimmerian unconformities, ZIEGLER, 1990).

To the NW. in the prolongation of the central horst, a synsedimentary salt pillow grew inside the

Rawa Mazowiecka basin segment, indicating extensional conditions also in the central part of the

trough. Observed thickness changes in the NW are partly the result of Zeichtein salt displacements

underlying the Lower Triassic sediments.

During the EARLY-MIDDLE JURASSIC subsidence patterns were more uniform (Fig. 3 E-F). Activity

along the Holy Cross fault had almost ceased. By this time, the basin had assumed the geometry of a

large half graben dipping towards the NE, due to a continued activity along the north-eastern Nowe

Miasto - Ilza fault (NMIF) system. During the Early Jurassic the NMIF propagated southeastwards as a

system of right-stepping en echelon faults (Fig. 3 E). During the Middle Jurassic this bounding fault

zone evolved into rectilinear feature. The evolution of such an en echelon normal fault pattern consisting

of straight faults concentrated within a single band, may characterize oblique rifting as proposed by

Tron & Brun (1991). Therefore, we suspect southeastward propagation of this fault, controlled by

highly oblique sinistral NNE transtension. During the Early Jurassic, the surface extent of the basin had

decreased. The basin flanks were uplifted; simultaneously the thickness gradients increased, though

subsidence rate did not reach great values (a little more than 50 m/Ma) (Fig. 3 E).

Across the Nowe Miasto-Grojec fault zone (1 and lb Fig. 3 E-F) depocenters are offset, the polarity

of the half grabens switching during the Middle Jurassic. Such linking between basin segments of

diferent polarity across transfer zone are already evident in the Late Permian map (Fig. 3 A), however

with an opposite sense.

The Late JURASSIC was an episode of overall subsidence that was not associated with high thickness

gradients (Fig. 3 G). The basin expanded and downwarping of the basin floor was greater over the entire

area. Isolines of subsidence rate trend NW-SE, parallel to the border of the East European Platform. The

former stability characterizing the Southwest region had come to an end. However, there is no evidences

for synsedimentary activity along the former basin bounding faults. Therefore the hypothesis of a Late

Jurassic rifting phase in this area (KUTEK, 1994) cannot be validated. A Late Jurassic extensional

episode was proposed also for the central and northwestern part of the Polish Trough by DADLEZ et al.

(1995).

The decreasing of longitudinal asymmetry of the basin presumably resulted from the linking of the

southeastward propagating described segment with a supposed new one, located in the south-east

(present Carpathians) and developing northwestward.

The preliminary results on CRETACEOUS maps (HAKENBERG & SWIDROWSKA, in prep.) show that in

the area of the Holy Cross segment of the Polish Trough, a period of accelerated subsidence is recorded

during the Turonian and Coniacian. It occurred just before the first stage of tectonic inversion, Santonian

in age. In the central and northwestern parts of the Polish Trough, a similar phase of subsidence

acceleration occured during Cenomanian times (Dadlez et al., 1995) and is followed by the beginning

of the tectonic inversion during the Turonian and Coniacian (JASKOWIAK-SCHOENEICHOWA &

KRASSOWSKA, 1988).

JULIETTE LAMARCHE ETAL.

Micro-structural data

Micro-structural analyses provide information on the Late Permian-Early Triassic rifting period. In

Devonian rocks, highly folded by Variscan tectonics, we observed numerous open fractures showing a

complex history (Fig. 4). These fractures trend roughly N-S and cross-cut Variscan folds. Thus they

obviously post-date Variscan folding. The lips of the open fractures are covered by calcite. The calcite

fibers grow perpendicular to the lips, showing that the opening occurred perpendicularly to the fractures

plans. This opening is attributed to an E-W extensional and N-S compressional strike-slip regime (o 1 N-

S. o2 vertical, c3 E-W). It can be related to the dextral wrench regime along the TTZ dated as Permo-

Carboniferous and affecting western and central Europe. In the core of this calcite cover, occure red

sandstones, dated as Late Permian-Early Triassic (Lewandowski. in preparation). This sediment

contains clasts of the calcite fibers, and clasts of the Devonian host rock (limestone). This characterizes

a second phase of fracture opening that was accompanied by sediment infilling during Late Permian-

Early Triassic times. As such it is taken as evidence of the early rifting period. On the red standstones

and the pieces of broken calcite and Devonian limestone contained in it, we observed superimposed

strike-slip slickenside lineations. As they affect the Late Permian-Early Triassic sediments, this

deformation occurred later. The dextral sense of slickensides on the N-S oriented fracture plane is

compatible with a NE-SW trending major Laramide compression (see section: Tectonic inversion).

RZEPKA QUARRY

20cm

Calcite 1

Givetian limestone

Dextral striations

within Lower

Triassic

Carbonated

red sediment

age unknown

Triassic red

with clasts

limestones

id calcite 1

Calcite 2

Fig. 4.— Example of sedimentary dyke in the Givetian limestones of Rzepka quarry (SW part of Holy Cross Mountains)

showing a polyphased opening and the dextral reactivation: see explanations in text.

Fig. 4 .— Example de filon sedimentaire dans les calcaires du Givelien de la carriere de Rzepka (Sud-Ouest des Montagnes

Sainte Croix) montrant une ouverture polyphasee el une reactivation dextre ; cf explications dans le texte.

Source: MNHN, Paris

MESOZOIC DEVELOPMENT AND DEFORMATION OF THE HOLY CROSS MOUNTAINS (POLAND) 83

Excepted this illustration for first extensional stages during the Late Permian-Early Triassic, there are

no obvious traces of the Mesozoic extension in terms of microtectonic structures. We investigated

numerous sites in the Holy Cross Mountains, and did not find obvious normal faulting despite of the

tectonic subsidence regime. The lack of extensional data may partly result from the age of the

investigated rocks. Most of them were of Late Jurassic age. Rocks of other ages crop out in very few

areas and their lithologies are not favorable for palaeostress investigations. However the Palaeozoic

rocks in the core of the Holy Cross Mountains, do not provide evidence for normal faulting data. Thus it

is likely that normal faults were localized in specific areas, not accessible todays. Thus the outcrops we

investigated did not provide information about the Late Permian-Early Triassic and Early Jurassic stages

oi subsidence, characteristic for their important synsedimentary faulting. As third Late Jurassic

subsidence stage was not accompanied with significant fault activity, this may explain the lack of

corresponding micro-tectonic features. Nevertheless, we demonstrated from boreholes studies (section:

Subsidence and fault pattern) the occurrence of some important synsedimentary activity along border

faults (Nowe Miasto-Dza fault, and Holy Cross fault. Fig. 3), specifically during the Triassic and Early

Jurassic.

TECTONIC INVERSION

After the Late Permian to early Senonian subsidence period, the Polish Trough was affected by

compressional deformations resulting in its inversion during the late Senonian and Palaeocene, and the

uplift of the so called "Polish Swell". This inversion results in uplift of the Holy Cross Mountains,

faulting of its Palaeozoic basement and folding of the Late Permian and Mesozoic sediments (Fig. 2).

The Polish Swell trends NW-SE, strictly parallels and is superimposed on the Teisseyre-Tomquist Zone.

Tectonic inversion being so obvious and well documented, we aim to determine the precise orientation

and evolution of the stress pattern during the tectonic movements.

METHODS OF INVESTIGATION

In the field, we attempted to differenciate successive tectonic events and where possible, to establish

their relative chronology and date them. Arguments for relative chronology between faulting and folding

are the tilting of fault systems during subsequent stage of folding, or on the contrary, the primary

position of faults cross-cutting through previously folded rocks. Successive events of faulting are

deduced from the superposition of successive striae on the same fault plane or from the cross-cutting

relationships between different sets of faults. On the other hand, compressional events were often

accompanied by horizontal tectonic stylolites. The relative position of the stylolitic peaks compared to

the bedding and the cross-cutting of sets of stylolites also constrain the sequence of tectonic events.

Where available, sedimentary filling of open fractures may permit dating of activity along fractures.

Sometimes, the overprinted deformation (slickensides) on the sedimentary fill of fractures can be used to

date their reactivation.

The sequence of events being recognized in the field, we computed the orientation of palaeostress

axis by the mean of fault-slip data inversion following the Angelier's method (ANGELIER, 1990). This

method is based on the shear-stress relationships. The inversion of fault data consists of determining the

reduced stress tensor knowing the direction and sense of slip on numerous faults of various orientations.

The computation allows to determine the orientation of the main stress axes cl, o2 and o3, responsible

tor the faulting (ANGELIER, 1990). The sense of motion on individual fault is determined in the field: we

measured the direction and plunge of the faults and the slickenside lineations.

AGE OF THE DEFORMATION

The large scale features of the Laramide deformation was due to the inversion of the Polish Trough

(KUTEK & GlaZEK, 1972). In the Holy Cross Mountains surroundings, the youngest folded rocks are

Maastrichtian in age. The folds are sealed by Palaeogene sediments (Fig. 2), dated as late Eocene in the

axial part of the Middle Polish Swell. Most authors agree with a Maastrichtian and Palaeocene age of the

JULIETTE LAMARCHE ETAL.

tectogenesis. On the geological maps of Poland (scale 1:200 000), the Palaeogene rests unconformably

on Maastrichtian strata. Correspondingly the deformation is said to be "Laramide” sensu lato. However,

in the Holy Cross Mountains, folds on the SW part are not covered by Palaeogene sediments. The

nearest Cenozoic deposits resting unconformably on Cretaceous or older rocks, occur on the southern

part of the Holy Cross Mountains. They are Miocene in age (Badenian). Thus in the area of the Holy

Cross Mountains the age of the observed deformation is stratigraphically less well constrained. During

this long gap a complex and polyphased deformation could occurred as discussed below.

Table 1.— Palaeostress results in investigated sites, from left to right: name of the site; coordinates: lithology; age of rock;

stress regime : S = strike-slip faulting, R = reverse faulting. N = normal faulting; n: number of fault data; ol. o2.o3:

maximum, medium and minimum stress axes respectively; <J) = (o2-o3)/(ol-o3) ratio of stress differences; RUP:

estimator as refered to ANGELIER (1990): a: average angle between observed slip and computed shear: Q: quality

estimator of the fault data (A = good, B = fair. C = poor). All angles are in degree.

Tableau I.— Resultats des paleo-contraintes dans les sites etudies, de gauche d droite : nom du site : coordonnees ; lithologie :

age de la rache ; regime de contraintes : S = decrochant, R = inverse, N = normal; n : nombre de donnees de failles ;

ol. 02. o3 : contrainte respectivement maximale, intermediate et minimale ; ip = (o2-o3)/(ol-o3) rapport de forme ;

RUP : estimateur de qualite f Angeuer, 1990); a : angle rnoyen entre hi strie observer et le cisaillement calcule ; Q :

estimateur de qualite de la population de failles (A = bon, B = rnoyen, C = mauvais). Tons les angles sont en degres.

Name

Lat. °

Long. °

lithology

age of rocks

Stress

regime

trend plunge

trend

plunqe

ct3

trend plunqe

FLP

Skarbka

50,36

21.33

limestones

U.Oxf. L.Kim

1 0

289

162

0,4

Baltow

50,36

21,33

limestones

M.Oxf.

223

314

0,7

247

343

0,6

Ozarow

50,34

21,07

lime, marles

U.Kim Turo.

294

125

0,3

224

340

0,4

Jaworznia

50,31

20,2

limestones

Devonian

225

315

101

0,3

Gniezdziska

50,31

20,03

limestones

M.Oxf.

215

1 6

101

314

0,2

231

139

329

0,3

Zagnask

50,34

20.32

limestones

Devonian

221

124

316

0,3

343

239

1 4

0.4

1 1

Malogoszcz

50,29

20,09

clays sandst.

Kim. Alb.

235

1 4

141

0,4

Checiny

50,28

20,16

limestones

Frasnian

256

1 1

115

348

0,3

Ostrowka

50,3

20,12

lime, clays

Frasnian

200

1 4

295

1 8

0,6

237

1 6

328

0,4

Sobkow

50,25

20,16

limestones

Kim.

122

299

0,1

237

119

330

0,4

1 2

136

1 1

282

1 9

0.3

1 3

Wierzbica

50,25

20,16

limestones

M.U.Oxf.

306

167

0,7

1 2

Wolica

50,26

20,16

limestones

Oxf.

247

338

154

0,4

Starocheciny

50,27

20.17

limestones

Oxf.

1 6

1 3

153

273

1 9

0,3

1 1

Debska Wola

50,26

20,21

limestones

Oxf.

1 8

268

149

1 0

0,2

1 7

Wisniowka

50,33

20,32

quartzites

Cambrian

175

355

0,4

Czarnow

50,32

20,2

limestones

Frasnian

1 1

212

304

122

1 1

0,2

1 3

167

1 1

310

0,5

Rzepka

50,28

20,16

dolomites

Givetian

1 3

252

162

0,7

Wietrznia

50,3

20,23

limestones

Frasnian

301

123

0,4

1 1

155

289

0,3

Kadzielnia

50,3

20,22

reef lime.

Frasn. Fam.

191

287

0,3

1 7

357

232

0,3

1 3

Laskowa

50,33

20,21

dolomite

Givetian

212

343

120

1 0

0,5

1 98

1 4

291

0,5

1 5

100

213

1 1

0,4

1 2

354

140

264

0,6

1 3

1 2

332

240

0,1

1 6

Jazwica

50,28

20,2

lime. marl.

Frasn. Fam.

286

1 1

191

0,4

1 2

1 9

265

1 5

174

1 3

0,2

348

247

0,4

1 2

Josefka

50,3

20,3

lime, clays

Give, to Fam

156

246

1 0

0,2

1 1

279

187

1 7

0.1

189

1 5

280

0,3

1 4

105

273

0,5

1 3

Source: MNHN, Paris

MESOZOIC DEVELOPMENT AND DEFORMATION OF THE HOLY CROSS MOUNTAINS (POLAND)

Micro-structural analysis and palaeostress reconstruction

We collected microstructural data at 61 sites in the Holy Cross Mountains (active and old quarries

and natural outcrops) including 55 in the Mesozoic formations. In 22 of them, data allowed us to

compute palaeostresses.

The main Laramide direction of compression detected in the field and characterized in terms of

palaeostress tensor is a NE-SW compression (Figs 5 and 6) (see also JAROSZEWSKI, 1972;

SWIDROWSKA, 1980). We recognized this shortening over all the Holy Cross Mountains, in the

Mesozoic rocks as well as in the Palaeozoic ones. At most sites it is characterized by conjugate strike-

slip fault system (Fig. 7A). In scarce sites this compression is characterized by conjugate reverse faults

(Fig. 7B). In sites where the bedding is steep, the faults system appear tilted as well as the strata

Therefore the faulting took place before the folding, while the bedding was flat. Stylolitic peaks trendin'*

about N050 further constrain the NE-SW direction of compression ^Fig. 7C). The stylolitic peaks still

parallel to the bedding planes in the steep limbs of the folds. This is illustrated in figure 7D where the

stylolitic peak symbols are located on the bedding plane traces. This means that the stylolitic peaks

formed horizontally when the bedding was Hat. and were subsequently tilted during the folding of the

strata.

Fig. 5.— The Laramide palaeostress pattern in the Holy Cross Mountains. The NE-SW compression is marked by the

convergent black arrows at each measured site.

Fig. 5 .— Champ cle conlraintes laramien elans les Montagues Sainte Croix. La compression NE-SW est ftguree par les flashes

convergentes noires localisees stir chaque site de mesures.

JULIETTE LAMARCHE ETAL.

N-S COMPRESSION

NE-SW COMPRESSION

E-W COMPRESSION

UPPER JURASSIC

rocks

EUia* S«*c»

Starccbeciny

Balia* Oarcw Malcgawci Sc**o* VWica

# Bf #

Set* a* (V»M<toska Oetofcawda Cnezdnska Werzbca

Skvt*a Balia*

Ckarow Oieony

MIDDLE DEVONIAN

rocks

Cmto» WtovVa Jar***

Zagwk JoMlka Jotetka laikowa

La»*o»a Joiaf'J

- 0 - 0 ^

auowka ClUONka Jawaaia Zagnask

Czamow Kadz.W.na VWmma La»kowa

# & & 0*0

Jazvrca Jazwica Rz«i*a Jcaelka L*iko*a

Josefka La»ko*a

Jazwica jazwita

WUfKMU

♦ DIRECTION OF

♦ COMPRESSION

♦ DIRECTION OF

♦ EXTENSION

*§1

WiSO>ON*a

Fig. 6 .— Schematic representation of post-Variscan brittle micro-structures and palaeostress computation in the Holy Cross

Mountains (direction of compression and extension as black arrows: lower hemisphere Schmidt projection). The main

Laramide event corresponds to the NE-SW compression of the central vertical column.

Fig. 6.— Representation schematique des micro-structures cassantes post-varisques et paleo-etat des contraintes dans les

Montagues Sainte Croix (/leches noires: directions de compression et d’extension ; hemisphere inferieur projection de

Schmidt). L'evenement laramien principal correspond a la compression NE-SW dans la colonne centrale.

In some Palaeozoic outcrops, we described N-S calcite veins with a sedimentary fill (cf. section:

Micro-structural data). This fill, that was dated as Late Permian-Early Triassic, was affected by dextral

movements (Fig. 4). The dextral motion on N-S fault planes is coherent with the NE-SW shortening and

would be conjugated to a sinistral movement on nearly E-W faults. That means that in the basement,

pre-existing N-S structures were reactivated whereas in the cover new conjugate strike-slip faults were

formed.

Some sets of faults indicate other directions of compression. One direction is about N-S, marked by

conjugate strike-slip faults. This direction is local and poorly constrained in Mezosoic formations. On

the opposite, it is well determined in the Palaeozoic rocks (N-S compression in Middle Devonian rocks,

Fig. 6). As corresponding faults cross-cut the Variscan folds, they are post-Variscan. The age of this

event still uncertain. It could be related to the late Variscan N-S compression and E-W extension as

postulated for the calcite veins openning (section: Micro-structural data), as well as to a step of

deformation related to the Laramide tectonics.

An other direction of compression trends about E-W, and is characterized by conjugated strike-slip

faults in Mezosoic rocks and further constrained by E-W stylolitic peaks. The E-W stylolites show

sequencial relationships both with the N050 ones and with the bedding. In Wola Morawicka quarry (SW

border of the Holy Cross Mountains), a bedding plane cleared over a large surface allowed the

Source: MNHN. Paris

MESOZOIC DEVELOPMENT AND DEFORMATION OF THE HOLY CROSS MOUNTAINS (POLAND)

GNIEZDZSKA QUARRY

Fig. 7.— Example of typical Laramide structures in the Jurassic limestones in the Sobkow and Griiezdziska quarries. A,

conjugate strike-slip faults and palaeostress computation (faults as thin lines ; palaeostress axes as five (of) four (o2)

and three (o3) pointed stars; direction of compression and extension as black arrows; lower hemisphere Schmidt

projection); B, conjugated reverse faults and palaeostress computation; C, relationship between stylolites and bedding

planes.

Fig. 7.— Exemple de structure laramienne caracteristique dans les calcaires jurassiques des carrieres de Sobkow et

Gniezdziska. A. failles decrochantes conjuguees et calcttl de paleo-contraintes (lignes fines .-failles, axes de paleo-

contrainte : etoiles a cinq (ol) quatre (o2) et trois (o3) branches, fleches noires : directions de compression et

d’extension, hemisphere inferieur projection de Schmidt) ; B, failles inverses conjuguees et calcul de paleo-etat de

contraintes : C, relation entre les stylolites et la stratification.

observation of two sets of stylolites (Fig. 8A and B). The first one is N050 characteristic for the NE-SW

main Laramide shortening. The peaks were affected and partly dissolved by a second generation of

stylolites trending N090 in average (N095 on the Fig. 8). They were formed during an E-W

compressional event that occurred later than the NE-SW one (Wartolowska. 1972). N050 stylolitic

peaks stand parallel to the bedding planes (Fig. 8D). As shown on the stereoscopic projection, the peaks

symbols are located on the traces of the bedding. Thus the N050 stylolites occurred before the tilting of

the bedding, that means before the folding deformation related to a NE-SW compression (see section:

Large scale structures analysis). In this quarry orthogonal sets of joints developed without sequencial

relationships (Fig. 8C and D). However, the E-W set is more homogeneous and less scatered directions

than the N-S one. Moreover it is parallel to the E-W direction of compression deduced from the

stylolites. Thus it may result from the E-W compression event. The joints stand perpendicular to the

bedding. It is clear in the field as shown by the sketch C of figure 8, and on the stereographic projection

on which the intersection of the two sets of joints correspond to the poles to the bedding (open dots).

Thus the joints as well as the N050 stylolitic peaks are linked to deformation events which occurred

before the folding.

Large scale structures analysis

To the NW of the Holy Cross Mountains, the Radomsko elevation is related to en echelon folds (Fig.

2), dated as Laramide, like the folds in the Holy Cross Mountains. They affect Cretaceous rocks and are

blanketed by the Miocene rocks. These folds display a WNW-ESE alignment, identical to the Holy

Cross fault, and are isolated in the middle of a large NW-SE trending gentle syncline. Their "S" shape

suggests sinistral shear, coherent with the NE-SW major Laramide compression (POZARYSKI, 1976). We

carried out a detailed fault slip analysis on this area. The palaeostress computation show a single

direction of compression trending NE-SW. We interprete the en echelon folds as resulting from the

sinistral reactivation of the deep seated Holy Cross basement fault, synchronous with the NE-SW

Laramide shortening characterized in the Holy Cross Mountains.

JULIETTE LAMARCHE ETAL.

Fig. 8 .— Sequential relationship between stylolites, joints and tilting of bedding in Wola Morawicka quarry. A. stereoscopic

projection of stylolitic peaks measured on a cleared bedding surface and chronology between the NE-SW (1) and the E-

W (2) sets; B, sketch of the observed stylolite sequence on the bedding surface; C, sketch of the walls of the quarry

showing the tilting of the joints and of the bedding planes; D. stereographic projection of joints, stylolitic peaks and

bedding planes.

FIG. 8 .— Reunions chronologiques entre les stylolites, les joints et le basculement tie la stratification dans la carriere de Wola

Morawicka. A. projection stereoscopique des pics stylolitiques mesures sur une surface de stratification degagee et

clironologie relative entre les systemes 111 NE-SW et (2) E-W ; B. Schema des relations chronologiques entre stylolites

observes sur une surface de stratification : C, schema des murs de la carriere montrant le basculement des joints et des

plans de stratification : D. projection stereographique des joints, des pics stylolitiques et des plans de stratification.

In the SW part of the Holy Cross Mountains is located a narrow highly folded zone (Figs 2 and 5)

with folds wave lenght of 1 to 2 km. The axis of this zone trending NW-SE is oblique to the Palaeozoic

horst and parallel to the Teisseyre-Tornquist Zone. It forms the southwestern boundary of the uplifted

area (STUPNICKA, 1971). As proposed for the en echelon folds in the Radomsko elevation, the narrow

folded zone may result from the reactivation of a deep seated NW-SE striking basement fault during the

Laramide shortening, localizing above it the deformation in the Mesozoic cover.

The NE-SW Laramide shortening, oblique to the WNW-ESE Holy Cross fault caused its sinistral

reactivation (Radomsko Elevation) while the NW-SE striking basement fault was reactivated as a

reverse fault (SW border of Holy Cross Mountains). As a result, two different geometries of fold

developed in the Mesozoic cover above these deep seated large faults.

Source: MNHN, Paris

MESOZOIC DEVELOPMENT AND DEFORMATION OF THE HOLY CROSS MOUNTAINS (POLAND)

SYNTHESIS

Basin opening

From the Late Permian to the Middle Jurassic the Polish Trough propagated progressively towards

the SE by reactivation of the pre-existing crustal discontinuity of Holy Cross fault (during the early

continental rifting phase, i.e. in the Late Permian and Early Triassic time). The southeastwards

prolongation of the Nowe Miasto Ilza fault (Fig. 3), paralleling the Teisseyre-Tornquist Zone, occurred

later, mainly during Early and Middle Jurassic time. The geometry of the basin fill indicates many

similarities with features characteristic for rifting basins (COLLETTA et al., 1988; MlLANI & DAVISON,

1988; NELSON et al., 1992; RING, 1994; ROSENDAHL et al., 1992). These similarities are: (1) subsidence

connected with a big activity of bounding faults; (2) domination of clastic sediments at the beginning of

the basin opening, joined with (3) high subsidence rate (Fig. 3 A,B); (4) transverse asymetry of the

trough (Fig. 3 A, B, E, F); (5) changes of basin polarities resulting in the Z-shape subsidence axis (Fig. 3

A, F); (6) activity of transfert fault zone; and (7) developement of the accomodation zone expressed by a

ridge of relatively smaller subsidence in the central part of the basin (Fig. 3 A, C, D).

Three stages of high subsidence rate are recorded in the basin history; namely during the Late

Permian and Early Triassic, the Early Jurassic and the Late Jurassic. The first two episodes were strictly

connected with the tectonic activity along the major normal faults bounding the basin.

The southern part of the Polish Trough initiated during an early stage of intracontinental rifting

devoid of volcanism, probably due to simple shear regime during Late Permian and Early Triassic times

(lithospheric shear model of WERNICKE, 1981; ZIEGLER, 1990). In the field it is shown by an

extensional regime with opening and sedimentary filling of pre-existing N-S veins.

During the Middle and Late Triassic, faulting was associated with lithospheric flexuring

(HAKENBERG & Swidrowska, 1997) reflecting a vertical trajectory of the maximal principal stress axis

(cl). The Early and Middle Jurassic rocks of the basin was formed under sinistral NNE-SSW

transtensional stres regime which developed along the Teisseyre-Tornquist Zone, acting as oblique slip

fault. During the Late Jurassic, fault activity ceased and the basin entered apparently in the thermal sag

stage.

Basin inversion

The existence of different directions of compression and relative chronologies determined in the

Mesozoic sites indicate that the Laramide deformation occurred gradually. The main compression trends

NE-SW. It caused large scale structures involving previous micro-scale features. We saw that the first

markers of the NE-SW compression were N050 trending horizontal stylolitic peaks. There is no

available relative chronology between the stylolites and the faulting. But the conjugate strike-slip

faulting and the NE-SW stylolites occurred both before the folding, when the bedding was still Hat. An

E-W set of stylolites indicates an E-W compression subsequent to the NE-SW one. This compressional

phase was also marked by orthogonal sets of joints, also prior to the folding. Finally, with increasing

deformation, the Holy Cross Mountains were uplifted and folded.

The main folding stage in the Mesozoic cover is related to the reactivation of the deep Palaeozoic

structures. On the NW-SE fault, the perpendicular NE-SW trending Laramide shortening caused a

reactivation as reverse fault. It is revealed by NW-SE folds in the cover of the Holy Cross Mountains,

while on the oblique WNW-ESE Holy Cross fault, the Laramide shortening provocated a sinistral strike-

slip reactivation, reavealed by the en echelon folds in the Radomsko elevation. The Laramide

compression also reactivated smaller inherited structures: for instance the N-S sedimentary dykes

originated from the Late Permian-Early Triassic rifting extensional period, were favorably oriented for

reactivation as dextral strike-slip faults.

JULIETTE LAMARCHE ETAL.

CONCLUSION

The Late Permian-Mesozoic Polish Trough basin developed over a complex basement. The analysis

of the iso-subsidence curves in the Holy Cross Mountains area shows that the shape of the basin was

characterized by two directions, related to (1) the inherited Palaeozoic faults of which the Holy Cross

fault is a major one, and (2) the deep Teisseyre-Tornquist Zone resulting in the NW-SE faults as for

instance Nowe Miasto-Ilza fault. Some of the synsedimentary normal faults active during the basin

evolution were reactivated as reverse strike-slip faults during the Laramide inversion.

We pointed out variable subsidence rate from the Late Permian to the Late Jurassic characterized by

three stages of higher subsidence rates : Late Permian-Early Triassic, Early Jurassic and Late Jurassic.

The palaeostress computation revealed a N-S compression and an E-W extension that we associate to

the early stage of rifting during the Late Permian-Early Triassic.

I he Laramide inversion resulted from a NE-SW compression characterized by (1) uplifting of the

Holy Cross Mountains, and (2) reverse reactivation of the NW-SE bounding faults and of the WNW-

ESE basement fault and by folding in the Mesozoic cover. The NE-SW compression applied to the

WNW-ESE Holy Cross fault resulted in the developpement of en echelon folds in the Mesozoic

sedimentary cover and sinistral shear reactivation of the deep seated fault. The palaeostress pattern

computed from the minor faults analysis is coherent with the information provided by large scale folds.

The detailed analysis of microstructural data made obvious a complex continous deformation, starting

with joints, stylolites and faults development, all of them being subsequently tilted during the folding.

The field investigation, palaeostress computation and subsidence analysis from borehole data, were

necessary to get a synthetic view and understanding for basin subsidence, inversion process and role

played by crustal features responsible for deformation localization.

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The Mid-Cretaceous events in eastern Europe:

development and palaeogeographical significance

Evgenij J. BARABOSHKIN" 1 , Ludmila F. KOPAEVICH"'

& Alexander G. OLFERIEV 121

"Department ot Historical and Regional Geology, Geological Faculty. Moscow State University

Vorobjovy Gory; 119899, Moscow, Russia

1:1 PGO "Centrgeologia", Geosintez, VarshavskoeShosse, 39A, 113105, Moscow, Russia

ABSTRACT

Biostratigraphy and regional peculiarities of the Mid-Cretaceous (Albian to Turonian) of the Russian Platform and its south

framework are discribed in the paper. The similarity in the fossil content permits the application of the standard west European

ammonite and inoceramid zonation and gives a possibility to recognize some of the wide - distributed bio-events ( Turrilites

coshims, P rae cl i no cam ax plenus for example). The fauna assemblages support the idea that the studying area belongs to the

eastern part of the European palaeobiogeographical area during the Mid-Cretaceous. At the same time, short-term boreal

invasions were recognized for the early Albian due to the opening of submeridional seaways. Analysis of sedimentary

successions and unconformities of the first order demonstrates eustatlc and regional tectonic control of basins history. The

sedimentary succession of the Russian Platform reflects the record of the second order sea-level changes. For the Hercynian

Irame. the tectonical overprint of the sea-level effect is typical. Various combinations of these factors and their consequences

resulted in the general style of sedimentation (i.e. palaeogeography) and completeness of geological record. An observation of

the main basin events (sedimentary, anoxic and volcanic) demonstrates that all of them did not appear simultaneously, but with

a short time - shift.

RESUME

Les evenements du Cretace moyen en Europe orientale : developpement et signification paleogeographique.

La biostratigraphie et les particularity regionales du Cretacd moyen (Albien a Turonien) de la plate-forme russe et de sa

bordure sud sont analysees dans cet article. La similitude du contenu fossile permet l'application de la zonation standard

occidentale a ammonites et inocerames et donne la possibilite de reconnaitre quelques bio-evenements mondiaux (Turrilites

costatus, Praectinocamax plenus par exemple). Les assemblages fauniques eonfortent 1‘idee que la region etudiee appartient a

Baraboshkin, E. J.. Kopaevich, L. F. & Olferiev, A. G„ 1998. — The Mid-Cretaceous events in eastern Europe:

development and palaeogeographical significance. In: S. Crasquin-Soleau & E. Barrier (eds), Peri-Tethys Memoir 4:

epicratonic basins of Peri-Tethyan platforms, Mem. Mus. natn. Hist, nat., 179 : 93-110. Paris ISBN : 2-85653-518-4.

Source: MNHN. Paris

EVGENIJ J. BARABOSHKIN ET AL.

brfeves o»t t* reconnues per 1, base de rAlbic, “iffiS

sedimentaires el dee discordances dc premier ordre demon enUe £„“£ „ ’ raer dlsecond ordre. Pon, 1.

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INTRODUCTION

The investigation is a contribution to the "Peri-Tethys Program". It is a synthesis based on numerous

previous publications and new data obtained by the authors. Earlier geological studies focused mainly

on general stratigraphy and lithological aspects of the subject. Detailed stratigraphy and event analysis

we^Toutof interest The first works on t£t topic were made for the Russian Platform (Sasdncva &

Sasonov. 1967) and then for Mangyshlak and Turkmenia regions (SAVELIEV 1971 NaidW \et al

1904 1995 - TASHLIEV & TOVB 1 NA. 1992). It was demonstrated that different events had ditterent

importance in the global sense. Recently comparable data were obtained for the Mid-Cretaceous interval

of the Russian Platform and for the Crimean, northern Caucasus and Turkmenian ^memory'basins

(Great Balkhan and Tuarkyr. Fig. 1). A preliminary event scale was published in BARABOSHKIN &

KOPAEVICH (1996). Several groups of events are discussed in the paper: anoxic events, volcanic events

and significant stratigraphical gaps.

Re. l._ Map of the position of mentioned localities: 1. Aksu-Dere and Katcha - Bodrak Rivers sections, north-west Cnmea, 2

Kuma section, northern Caucasus: 3. Baksan River section, northern Caucasus; 4. Heu River section, northern

Caucasus; 5. Akusha section, northern Caucasus; 6 . Aksyirlau - Koksyirlau and Shetpe sections Mangyshlak 7

Besokty section. Mangyshlak; 8. Akkyr section. Tuarkyr; 9. Kiariz section. The Great Balkhan; 10, Vorona River

section. Riasan - Saratov Trough. Russian Platform; 11, Ulianovsk section, Simbirsk synecl.se, Russian Platform; 12.

Paromonovo section near Moscow. Moscow Syneclise, Russian Platform; 13, Eza River section near Vladimir, Moscow

syneclise. Russian Platform; 14. Borehole n°426. Smolensk district, Moscow syneclise, Russian Platform; 15. Borehole

n° 453, Kursk district, Moscow syneclise, Russian Platform.

Fig. /.— Carte de localisation. 1. coupes des rivieres Aksu-Dere el Katcha-Bodrak. nord ouest de la Crimee .2, coupe de

Kuma, nord du Caucase : 3. coupe de la riviere Baksan. nord du Caucase ; 4. coupe de la riviere Heu, nord du

Caucase ; 5. coupe d'Akusha, nord du Caucase ; 6. coupes d’Aksyirtau-Koksyirtau el de Shetpe. Mangyshlak : 7. coupe

de Besokty, Mangyshlak ; 8, coupe d'Akkyr. Tuardyr : 9. coupe de Kiariz, Grands Balkans ; 10 coupe de la riviere

Vorona, depression de Riasan-Saratov. plate-forme russe : 11. coupe d'Ulianovsk, synclinal de Moscou. plate-forme

russe ; 12, coupe Paramonovo pres de Moscou, synclinal de Moscou, plate-forme russe ; 13, coupe de la r,v, f re tzu

pres de Vladimir, synclinal de Moscou, plate-forme russe ; 14. forage n°426, district de Smolensk, synclinal de Moscou,

plate-forme russe : 15, forage n°453, district de Smolensk, synclinal de Moscou, plate-forme russe.

Source: MNHN, Paris

MID-CRETACEOUS EVENTS IN EASTERN EUROPE

BIOSTRATIGRAPHY AND GENERAL SEDIMENTOLOGY

Eastern Europe was a system of communicating epicratonic basins during the Mid-Cretaceous.

Geologically the area of investigations belongs to the ancient Russian Platform, the Hercynian Scythian

and Turan Platforms and to the Alpine mobile belt in particular (MlLANOVSKY, 1987-1991). The only

exclusion is the Peri-Caspian Basin that had its own geological history, which does not coincide with the

history of the surrounding area. It was already demonstrated that tectonic activity of those regions was

strongly different during Mid-Cretaceous time (NlKISHIN et al., 1998). The investigated Albian through

Turonian interval is characterized by various basin events and the main sedimentary change (terrigenous

to carbonate) around the Lower/Upper Cretaceous boundary.

Albian

Albian biostratigraphy is based mainly on ammonites for all of the investigated area. All regions

could be correlated by the zonation similarity (Fig. 2). It reflects, of course, general characteristics of

water mass and climate.

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BARABOSHK1N.

19 9 6 and 1997.

CRIMEA

BARABOSHKIN,

in press,

NORTH CAUCASUS

BARABOSHKIN.

1996

RUSSIAN PLATFORM

SAVELIEV. 1 9 9 2.

modified by BARABOSHKIN,

1 9 9 6 and in this paper,

MANGYSHLAK & PERI CAS PI AN

SAPOZHNIKOV, 1973,

LUPPOV, 19 8 1,

BARABOSHKIN,

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spathi

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Fig. 2.— Biostratigraphic zonation of the Albian of Crimea, northern Caucasus, Russian Platform. Mangyshlak - Peri-Caspian

and Great Balkhan area based on ammonites.

Fig. 2 .— Zonation basee sur les ammonites pour I'Albien de Crimee. du nord Caucase. de la plate-forme russe, du

Mangyshlak, de la region peri-Caspienne el des Grands Balkans.

EVGENIJ J. BARABOSHKIN ETAL.

The biostratigraphic scheme of Crimea - Northern Caucasus region is close to the “standard”

zonation for mediterranean region (HOEDEMAEKER el al., 1995; BARABOSHKIN. 1996). It is also very

similar to the zonation of the historical Albian “stratotype" (DESTOMBES, 1979) and to the well-

investigated zonation of European province (OWEN, 1996).

Crimea

The main peculiarity for Crimea is the great difference between the disposition of plains and

mountains and completeness of ammonite successions (BARABOSHKIN, 1996, 1997). Marine

sedimentation was more continuous in the plain Crimea than in the mountain Crimea and most of Albian

ammonite zones are present there (LESCHUKH, 1992). Albian successions in the plain Crimea are

presented mainly by coarse terrestrial facies, being more fine-grained towards the end of the Albian,

especially in central Crimea. Terrigenous sedimentation changed into volcanic deposits in the middle

Albian (LESCHUKH, 1992), due to the opening of the back-arc rift basin on the border of plain Crimea

and Russian Platform (NlKISHIN el al. , 1998). Total thickness of Albian sediments varies from 250 to

about 1000 m in the depressions of the plain Crimea.

Crimea was mountain region even during Albian time. Sedimentation started there only in the late

Albian. in the beginning of Hysteroceras orbignyi Chron (YANIN & VISHNEVSKY. 1989;

BARABOSHKIN, 1996. 1997) and after a widespread tectonic phase in the end of Dipoloceras cristatum

Chron (Owen, 1996). Generally, it coincides with the beginning of Albian transgression in many other

regions. Because of the elevated primary position of mountain Crimea, its Albian sequences reflect sea-

level falls and rises very sensitively. The basal parts of the terrigenous Albian succession are very coarse

and typical for ingressive conditions (YANIN & VISHNEVSKY, 1989). They were replaced shortly by

terrigenous-carbonate sedimentation in Mortoniceras inflation Chron (YANIN & VISHNEVSKY, 1989;

BARABOSHKIN, 1996. 1997). The latest Albian sequence in mountain Crimea is characterized by

terrigenous deposition with thin tuff layers near the Albian/Cenomanian boundary. Total thickness of

Albian succession reaches 80-100 m here.

Northern Caucasus

Albian succession of northern Caucasus is represented mainly by clays with limestone/marl

interbedding, sandy in the base (BARABOSHKIN, 1996). It contains many stratigraphic gaps marked by

erosional surfaces, softgrounds and phosphorites. The most complete succession is the Akusha section

(Fig. 2) in Daghestan (BARABOSHKIN et al., 1997a). An important feature of Albian successions is the

presence of series of strongly dysaerobic to anoxic events represented by “black shales” and the absence

of a benthic fauna. Tuff layers are also present in the topmost part of the succession. They have exactly

the same position as in the mountain Crimea. Albian sediments reach 100-120 m thick in depressions

and are completely eroded in uplifts.

Russian Platform

Albian deposits of the Russian Platform were observed by many investigators, and a general

summary was published by Sasonova & Sasonov (1967), Baraboshkin (1991, 1996) and

BARABOSHKIN & MIKHAILOVA (1987). The distribution of Albian sediments is very irregular

(BARABOSHKIN, 1996). Even ill the depressions and syneclises different parts of the Albian are

preserved in different places because of the numerous stratigraphical gaps and unconformities. For

example, it was counted up to 30 morphologically expressed gaps (erosion surfaces, softgrounds, etc.)

per 0.5 m of succession in some sections of Ryasan - Saratov Trough. This means that complete sections

are absent here and that it is very difficult to build up a composite section. The lower Albian is

represented by cross-bedded sands with phosphorites in the top. It is preserved in depressions of the

central part of the Russian Platform as well as on top of the Voronezh anteclise. The basin was

characterised by boreal water masses (with an Arcthoplites fauna) during early Albian time. The middle

Albian is represented by an anomalously thin succession in comparison with lower and upper Albian

Source: MNHN, Paris

MID-CRETACEOUS EVENTS IN EASTERN EUROPE

because of the numerous and polyphase gaps. It consists of quartz-glauconite sands rich in phosphorites,

which were deposited in waters of moderate temperature (BARABOSHKIN, 1996). The transgressive

upper Albian is built up fine-grained sands, silts and clays (as usual) under the influence of warm

tethyan water masses (BARABOSHKIN, 1996). Originally upper Albian sediments were widely distributed

all over the Russian Platform, but they were eroded in many of regions during Cenomanian time. The

former existence of upper Albian sediments was reconstructed owing to the presence of redeposited

phosphatic pebbles in the base of Upper Cretaceous succession. The total thickness strongly varies, but

commonly is 20-30 m.

Mangyshlak and Peri-Caspian

Albian succession of Mangyshlak and Peri-Caspian is represented by shallow-water terrigenous

sediments, mainly by silts and sands with sandstone carbonate concretions. The lower parts of the

Albian succession are more fine-grained than the upper ones. Usually the coarsest parts of the section in

Mangyshlak belong to the middle - basal upper Albian. They are represented by near-shore cross-bedded

sandstones. In opposite, the coarsest interval of Albian successions is occurred in the uppermost Albian

in Peri-Caspian. It consists of near-shore to continental cross-bedded sandstones, gravelstones with

pebbles and plant remains. It has regional distribution and is not connected with salt diapirism. The most

of the sections are incomplete (SAVELIEV, 1971), so we draw up a composite section. Stratigraphic gaps

are different in morphology and extent of the stratigraphic hiatus. The most condensed intervals are

marked by phosphatic nodules and phosphorite "plates". Very strong condensation is typical for the

lower Albian as well as for the uppermost Albian in Mangyshlak, but the main hiatus is dated as the

basal upper Albian (SAVELIEV, 1971). This is due to the fact that the base of the upper Albian coincides

with the transgressive phase in this area. The upper Albian reflects the regressive phase, during which

deltaic and continental facies prograded into the Peri-Caspian basin. This phase was initiated by the

compression of the Hercynian Scythian-Turan Platform and upliftings in the South Urals. In the

Aktubinsk area of the Peri-Caspian, volcanoclastic sediments are also known in the uppermost Albian

(Sasonova & Sasonov, 1967). The total thickness of Albian sediments reaches 300-400 m up to 1000

m in Mangyshlak and the Peri-Caspian.

Great Balkhan

The Albian succession of the Great Balkhan is similar to that of the Mangyshlak is represented by

sandstones, silts and clays. The lower Albian is represented by near-shore cross-bedded sandstones with

small phosphorite pebbles, placed above erosional surfaces. Basin deepening is indicated by appearance

of clays and silts with interbedded sands near the lower/middle Albian boundary. The basin became

more shallow in the lower upper Albian. when cross-bedded phosphorite sandstones appear again. In

particular, the succession is similar to the Peri-Caspian, but finally it is characterized by the strong

deepening in the uppermost Albian and basal Cenomanian. The succession does not contain

volcanoclastic material, nor anoxic levels in comparison with the other basins discussed in the paper. It

reflects the shallower conditions of the basin and weak tectonic activity of the region. The total

thickness is about 400 m.

Cenomanian

Crimea

The main peculiarity of the Crimea Cenomanian series is the carbonate composition of the

succession: rhythmically - bedded marls and limestones. Marls can have different colours - from light-

grey till completely black or dark-grey. The Cenomanian succession is very similar in plain and

mountain Crimea except the thickness, which varies from 20-70 m in mountain Crimea up to 500 m in

the plain Crimea (Tarkhankut Peninsula). Cenomanian sediments are completely eroded in the

Simpheropol city region. The most complete sections consist of two sedimentary successions, which

coincide with global cycles of sea-level-changes (Kopaevich. 1997). The first one consists ot four

EVGEN1J J. BARABOSHKIN ET AL.

lithological units while the second contains three units (NAIDIN & ALEKSEEV, 1981). There is an

erosional surface between these successions with the distinctive Thalassinoides-type burrows. The bed

above is a glauconite marl with about 6-7 cm pebbles of limestones and sandstones of Taurik and

Bodrak Formations (Triassic - Liassic). The surface coincides with the “mid-Cenomanian non-

sequence”, which has very wide distribution (see Fig. 4). The latest Cenomanian is well - marked by the

appearance of the black (or dark) marly clays with silt-size quartz grains, glauconite, volcanoclasts, and

a complete lack of calcite macro- and microfossil remains (see Fig. 4, Aksu-Dere section). In the other

sections the boundary is usually represented by a submarine erosional surface or horizon with intraclasts

and "Radiolarian sands”. The lower sequence corresponds with the lower Cenomanian and the second

one - with the middle and upper Cenomanian. The stratigraphical subdivision of the upper part of middle

and upper Cenomanian is based on foraminiferal data only (Fig. 3).

Cenomanian biostratigraphy in Crimea is based mainly on ammonite and inoceramid assemblages

(Fig. 3). The biostratigraphic scheme is very close to the “standard" zonation proposed by KENNEDY

(1984). Only the uppermost part of the scheme differs since macrofauna is practically absent. The

inoceramid scheme is identical to that of Central Europe (TROGER. 1989, 1996). The planktic

foraminiferal zonation is also very similar to the European “standard” and the Mediterranean zonal

scheme (ROBASZYNSKI & AMEDRO, 1980; RoBASZYNSKl et ill. 1996).

Russian Plat form

Cenomanian deposits are irregularly distributed over the Russian Platform. Different parts of

Cenomanian - lower Turonian succession are preserved in different areas due to the numerous

stratigraphical gaps and unconformities. Normal marine sedimentation characterizes early Cenomanian

time only. The middle and especially upper Cenomanian deposits are strongly condensed and

represented by phosphorite horizons, phosphorite plates or are completely missing. This is the reason

why the Cenomanian - Turonian composite profile is built up from different sections. The Cenomanian

succession is represented only by terrigenous facies, mainly by quartz sand with small phosphorite

nodules, fragments of black Hints and with Thalassinoides burrows. Two phosphorite horizons exist: in

the base and in the upper part of the Cenomanian (Fig. 4).

Characteristic fauna of the Cenomanian time is very poor: rare ammonites, remains of bivalves, shark

teeth and benthic foraminifera. The first appearance of Praeactinocamax plenus marks the base of the

upper Cenomanian. The benthic foraminiferal zonation is the same for this region and adjacent areas

(VASSILENKO, 1961, AKIMETZ el al., 1992, NAIDIN et al., 1984) and similar to the west European

shallow water sections in south England, north Germany, north France and Bohemian Massif (CARTER

& Hart, 1977; ROBASZYNSKI & AMEDRO, 1980; Hradecka. 1996). There are several correlative

bioevents: appearance of Gavelinella cenomanica near the Albian/Cenomanian boundary; appearance of

Lingulogavelinella globosa at the lower/middle Cenomanian boundary and appearance of Brotzenella

berthelini inside the terminal part of the Cenomanian succession. Gavelinella cenomanica is a very

important Cenomanian marker. It represents the most conspicuous component of the Cenomanian

assemblage in different geographical regions. First occurrences of this species were reported from upper

Albian of France and south England, however, its maximal development falls into the Cenomanian. It

also represents the index species of the Cenomanian foraminiferal assemblage not only for the Russian

Platform, but also at the Mangyshlak and Peri-Caspian Basin (VASSILENKO, 1961; NAIDIN et al., 1984),

Poland and Germany, Bohemian Basin (HRADECKA, 1996). The distribution of this species in the

Cenomanian series of Crimea coincides with the distribution of Rotalipora appenninica. The first

Lingulogavelinella globosa appears in the middle part of the succession and indicates beginning of the

middle Cenomanian. The upper part of Cenomanian is strongly condensed or is absent. It exists in a few

complete sections only and contains poor foraminiferal assemblage, very similar to the one of the

Lingulogavelinella globosa Zone, but younger, because Brotzenella berthelini developed here.

Mangyshlak

Cenomanian through middle Turonian exists in terrigenous facies whereas carbonates are present in

the upper Turonian - Coniacian of the Mangyshlak. The middle Cenomanian - middle Turonian interval

MID-CRETACEOUS EVENTS IN EASTERN EUROPE

FIG. 3

Fig. -

ALEKSEEV, 1989

ALEKSEEV et al., 1995

NADDIN et al., 1984;

KOPAEVICH & WALASZCZYK.

MARCINOWSKI et al.,1996

1990

MANGY

SHLAK

CRIMEA

RUSSIAN PLATFORM

—\

MOLLUSCA

FORAMIMFERA

MOLLUSCA

-ORAMINIFERA

MOLLUSCA

FORAMINIFERA

ZONES

Cremnoceramus

deformis

Marginotnmcana

Cremn.

brogniarti

Gavelinella

Cremn.

brogniarti

Reussella

ketleri -

Cremnoceramus

rolundalus

renzi -

Cremn.

rolundalus

ketleri

Cremn.

rolundalus

Gavelinella

praeinfrasan-

coronata

Cremnocera-

tonica

Cremnoceramus

mus wallers-

Mytiloides

waltersdorfensis

dorfensis

incertus

Ataxophrag-

mium

nautiloides

Inoceramus

£ 2

c 3

Inoceramus

costellarus

5 -5

o £?

costellatus

I 1

costellatus

D-

Inoceramus

Si £

Inoceramus

lamarcki

Gavelinella

— J

lamarcki

Inoceramus

apicalis

Marginotnmcana

apicalis

moniliformis

i—

Mytiloides

pseudolinneiana

Mytiloides

hercynicus

Mytiloides

labiatus

Helveto-

globotruncana

Mytiloides

labiatus

Cavelinella

Mytiloides

labiatus

Globorotaliles

Helvetica

hangensis

Prae-

Mytiloides

kossmati

Mytiloides

nana

plenus

,,n . tl

mytiloides

Whiteinella

Mytiloides

hattini

Whiteinella

_ 1

archeocretacea

triangulus

archeocretacea

Prae-

actinocamax

Lingulogave-

Praeactinoca-

max plenus

Brolzenella

Rotalipora

cushmani

plenus plenus

linella

bertlielini

—1

Inoceramus

globosa

Acanthoceras

Linguloga-

pictus

juckesbrownei

velinella

Turrillites

globosa

Turri Hites

costatus

Gavelinella

costatus

Rotalipora

deecki

Shloenbachia

various

cenomanica

Mantelliceras

dixoni

Gavelinella

Mantelliceras

Rotalipora

Mantelliceras

cenomanica

—1

mantelli

appenninica

mantelli

Biostratigraphic zonation of ihe Cenomanian - Turanian of Crimea. Russian Platform and Mangyshlak - Peri-Caspian

area based on ammonites (for Cenomanian), inoceramids (for Turanian) and forammitera.

- Zonation nor les ammonites (pour le Cenomanien), les inoceramides (pour le Turonien) et les forammijeres du

Cenomanien - Turonien de Crimee, de la plate-forme russe, du Mangyshlak et de la region pen-Casptenne.

Source

100

EVGENIJ J. BARABOSHKIN ETAL.

is characterized by a very reduced sedimentation. Only the lower Cenomanian had “normal”

sedimentary rates and a complete record being relatively thick in the most sections. The middle and

upper Cenomanian are strongly condensed or missing. There are two phosphoritic horizons inside the

Cenomanian: the first one is in the base of Cenomanian and the second one at the lower/middle

Cenomanian boundary. The thickness of Cenomanian changes from 35 up to 50 in in the Mangyshlak.

The biostratigraphic division of the Cenomanian of this area based on ammonites and inoceramids.

As for Crimea, the ammonite zonation based on the “standard” schemes, proposed by KENNEDY (1984).

The inoceramid scheme is the same as in central Europe (TROGER. 1989. 1996). Planktic forams are

very rare in Mangyshlak and were recognized in the restricted intervals of the sections. Benthic

foraminiferas are very abundant, in the contrary, and have long stratigraphical ranges. The base of the

Cenomanian is marked by the appearance of the ammonites Neostlingoceras, Mantelliceras and

Schloenbachia. The beginning of the middle substage is characterized by the mass occurrence of

Turrilites costatus. The upper Cenomanian is well developed in isolated sections (Aksyirtau -

Koksyirtau) and nicely marked by Praeactinocamax plants event. Neocardioceras juddi appears in the

top of the Plenus Zone (Marcinowski et al., 1996).

The foraminiferal zonal scheme is based on distribution of benthic taxa and therefore is of limited

value for correlation. Luckily, the same levels exist in the Mangyshlak as in the other regions described:

(1) the appearance of Gavelinella cenomanica near the Albian/Cenomanian boundary; (2) the

appearance of Lingulogavelinella globosa in the middle Cenomanian and (3) Brotzenella berthelini in

the upper Cenomanian.

TURON1AN

Crimea

In Crimea the Turonian succession is represented only by carbonate sediments. The lower part of the

succession consists of marls with flint intercalations at its top. A minute omission surface (1.4 m above

the base) and an incipient hardground (2 m above the base) exist in this part. The upper part of the

Turonian is built up of marly stylolitic limestones. The thickness of the lower part is 20 m and the

thickness the upper part is about 18 m. This succession terminates by a mature hardground (NAIDIN,

1987) with distinctive Thalassinoides- type burrows and very hard cemented surface.

The marls and flinty marls belong from the base to the top Mytiloides mytiloides Zone (1),

Mytiloides labiatus Zone (2) and Mytiloides hercynicus Zone (3) (KOPAEVICH & W.ALASZCZYK. 1990).

These biostratigraphical subdivisions belong to the lower (1 and 2) and middle (3) Turonian. The lower

part of succeeding Stylolitic Limestones represents the Inoceramus lamarcki and I. costellatus Zones of

the middle Turonian and Cremnoceramus waltersdorfensis Zone of the upper Turonian (Fig. 4). The

upper boundary of the Turonian is recognized by the appearance of Cremnoceramus rotundatus, which

is assumed to correlate with the entry of Forresteria petrocoriense index ammonite of the lower

Coniacian. Some events of planktic and benthic foraminifers can be followed from the Crimea to west

European sections (e.g., RoBASZYNSKI & AMEDRO, 1980) inside Turonian. They are: (1) the common

entrance of numerous Whiteinella species; (2) the appearance of Helvetoglobotruncana Helvetica and

Globorotalites Itan gens is in the lower Turonian; (3) the first appearance of the of the genera

Marginotruncana and Gavelinella moniliformis in the middle Turonian and (4) the appearance of

“Grandes Rosalines ” ex gr. Marginotruncana coronatarenzi with Gavelinella cf. vombensis (Brotzen) (=

G. praeinfrasantonica (Mjatliuk) around the Turonian/Coniacian boundary (KOPAEVICH, 1996).

Russian Platform

Turonian sections of the Russian Platform consist of white and light-grey coarse chalk with

inoceramids fragments. Two thin layers (2-3 cm) of bentonite exist in the middle and the terminal part of

the sections. The thickness of the sections is about 25 m. The upper boundary of the Turonian could be

distinguished only by paleontological data.

Source: MNHN. Paris

MID-CRETACEOUS EVENTS IN EASTERN EUROPE

101

SEA-LEVEL CURVE,

after HAQelal., 1988;

AGE after

HARLAND cl al., 1989

RUSSIAN PLATFORM

Smolensk district,Borehole No.426

Kursk district,Borehole No.453

MANGYSHLAK

AKSVIRTAl - KOKSYIRTAU

MA.88.5-

imfl

Pig. 4.— Relative sea-level changes, main unconformities and anoxic events for Cenomanian - Turanian of Crimea. Russian

Platform and Mangyshlak - Peri-Caspian. Abbreviations in columns mean names of ammonite zones/subzones and

horizons illustrated on fig. 3. Same legend as fig. 5.

4 _— Variations du niveau marin, principales discordances et tenements anoxiques pour le Cenomanien - Turonien de

Crimee. de la plate-forme russe. du Mangyshlak et de la region peri-Caspienne. Les abreviations dans les colonnes

correspondent aux zones / sous-zones a ammonites et aux horizons de la fig..I Meme legende cpie fig. 5.

The faunal assemblage is very rich in inoceramids, with zones very similar to the one of Crimea,

west and central European regions (Fig. 3). The benthic foraminifera zonation includes the same levels

as in Crimea and Mangyshlak. The lower Turanian contains Gavelinella nana zonal assemblage, but

with high planktic foraminifera content in the base. This assemblage probably coincides with the

Whiteinella archeocretacea Zone in Crimea. The abnormal consistence of planktic foraminifera exists

near Turonian/Coniacian boundary as well as in the Crimea and Mangyshlak.

Mangyshlak

Turanian succession begins by a thin layer of black clays (0.2 m). A second horizon ot black clays is

placed higher, above 0.9 m of green limy clays and shows Chondrites structures. The black clays lie

inside poorly cemented siltstones and sandstones. The total thickness is about 10 m.

The overlying lithological unit is built up of yellow-greenish soft marly quartz - glauconite

sandstones. Two concretiona] horizons exist in the lower and middle parts of the succession, which are

characterised by inoceramids. The thickness is 25 m.

The following carbonate succession begins with a horizon with numerous dark-brown phosphorite

concretions in a sandy marl matrix. The thickness is 0.5 m. The phosphatic concretions are very rare

higher in the succession. The numerous fauna, represented by ammonites, echinids and brachiopods, is

phosphatized. The top of the succession is represented by coarse "spherical chalk" with hardground

surfaces on the Turonian/Coniacian boundary.

Turanian biostratigraphy in Mangyshlak mainly based on inoceramid fauna. The inoceramid

zonation is similar to the one of central and eastern Europe. It is more precise than the ammonite

zonation for the whole stage. The inoceramid fauna is well represented for both condensed and non-

condensed intervals (Naidin et al.. 1984; Marcinowski et al.. 1996). The base of the Turanian is

determined by the appearance of Mytiloides hattini and the lower 1 uronian inoceramid zonation

102

EVGEN1J J. BARABOSHK1N ETAL.

comprises three zones (Fig. 3). The lower/middle Turonian boundary is marked by Mytiloides

hercvnicus , and the base of the upper Turonian coincides with the first occurrence of Inoceramus

costellatus. The Turonian/Coniacian boundary is determined by the appearance of Cremnoceramus

rotundatus.

The foraminiferal zonation is as follows: the base of Turonian corresponds to the first planktic

foraminiferal Zone - Whiteinella archeocretacea and with an anoxic episode; the appearance of

Globorotalites hangensis is correlated with lower Turonian Mytiloides labiatus Zone; Gavelinella

moniliformis Zone coexists with middle Turonian Mytiloides hercynicus - Inoceramus apicalis -

Inoceramus lamarcki Zone and upper Turonian Ataxophragmium nautiloides with Inoceramus

costellatus - Mytiloides incertus Zones; the Turonian/Coniacian boundary is determined here by the

appearance of Reussella kelleri and high content of planktonic species of Marginotruncana (Fig. 3).

MAIN BASIN EVENTS

Anoxic events

Anoxic events were recognized only for the northern Caucasus area by analysis of total organic

carbon content (TOC. made in Moscow State University), magnetic susceptibility (Ax= X - X.. made in

Palaeomagnetic laboratory of Saratov State University) and fauna palaeocoenoses. Several dysaerobic to

anoxic events were recognized in the succession (BARABOSHKIN & KOPAEVICH, 1993).

The analogue of "Paquier Level" (Hart et al ., 1996) is weakly developed near the base of regularis

Zone (Fig. 5). It is characterized by absence of benthic fauna, development of Chondrites -beds and fine

lamination in clays.

Dysaerobic conditions prevailed in the middle Albian time. This view is supported by the

development of a Actinoceramus (Byrostrina) - Nucula benthic bivalve assemblage and high dispersed

pyrite content (Ax=60-70 units SI ; Baraboshkin et al., 1997b). The level extends from the base of

middle Albian up to roissyanum Zone with a maximum in spathi and roissyanum Zones.

For the upper Albian time three dysaerobic events were recognized.

The orbignyi - varicosum Zones are characterized by dysaerobic conditions, where the

Actinoceramus (Byrostrina)-Variamussium-Nucula benthic bivalve palaeocoenoses changed into an

Aucellitia palaeocoenoses. The maximum of anoxic conditions in this level was reached in the

varicosum Zone, where Ax is maximal (=80-90 units SI).

Dysaerobic conditions started in the uppermost part of the inflatum Zone and reached their maximum

in the middle of the rostratum Subzone, where Ax=60-80 units SI and TOC=5%. The level is probably

the analogue of “Breistroffer Level" (BREHERET & Delamette, 1989). This anoxic event was reflected

in Aucellina benthic paleocoenosis reduction in the Albian succession of northern Caucasus. In some

sections it could be recognized as fine-laminated interval (0.7-1 m) with rare belemnites.

The uppermost anoxic event found in the sections is in the perinflatum Subzone. This event was the

shortest one. with Ax=60-70 units SI. about 2% TOC and the same Aucellina palaeocoenoses reduction.

This event was interrupted locally by volcanic ash "rain”.

The development of Aucellina paleocoenosis is a typical feature of the northern Caucasus Basin,

indicating dysoxic conditions. In the Crimea and Mangyshlak - Great Balkhan areas, Aucellina are also

present in the sections, but they do not produce great populations because of the quite good bottom

oxygenation.

Upper Albian maximum sea-level rise coincides with the maximum of dysaerobic and anoxic-

conditions in a relatively shallow basin. The model of transgressive "black shales” (WlGNALL &

MAYNARD, 1993) could explain the appearance of such conditions, characterized by the coexistence of

“normal marine" nektonic and planktonic faunas with poor benthic assemblages.

Anoxic events are more easily recognizable in the Cenomanian time of the Crimea and northern

Caucasus areas, due to their lithological peculiarities and high TOC content. The analogue of the

"Bonarelli Level” was recognised near the Cenomanian/Turonian boundary. It is characterized by the

Source: MNHN. Paris

MID-CRETACEOUS EVENTS IN EASTERN EUROPE

103

existence of organic-rich sediments (•‘black shales”), the development of Chondrites beds and by the

absence of benthic fauna. Pre-Cenomanian sediments of these areas are characterised by ow 1UL

content with an important terrestrial component. During the Cenomanian, TOC increased, culminating

around the Cenomanian/Turonian boundary. Organic-rich sediments have progressively declined since

the Turanian, being replaced by “normal” sediments (Gavrilov & Kopaevich, 1996).

A dysaerobic event can be determined in the base of the lower Turanian in terrigenous facies of

Mangyshlak. It is represented by “black clays” with Chondrites burrows, rare remains of inoceramid and

ammonites. Above, sediments contain an exclusively planktonic foramimferal assemblage. This is the

only planktic zone for the whole Upper Cretaceous in Mangyshlak.

In the Russian Platform the Cenomanian/Turonian anoxic event is not represented in the sections.

Only a positive 5"C isotope shift helps to recognise dysaerobic conditions inside the Lower Turanian

succession, coeval with the anoxic event in the other areas.

Thus Cenomanian/Turonian organic-rich sediments occur in a wide range of different iacies from

planktic carbonate to terrigenous facies. It is easy to see that all dysaerobic and anoxic events coincide

with short-term sea-level changes (Fig. 4) and that the duration of the interval depends from long-term

sea-level change.

The same intervals of the Mid-Cretaceous are also characterised in the Atlantic and Mediterrenean

regions (REYMENT & BENGTSON, 1986. KUHNT et ai. 1992).

Volcanic events

Several volcanic events were recognised in the Crimea - Peri-Caspian region .The ™ost inter^ive

intermediate volcanism developed in the plain Crimea during the rifting stage in this region (NlKlSHlN et

a l 1998). n started in middle Alhian time and was most active during late Albian - early Cenomanian

times (LESCHUKH, 1992), when volcanic tuffs spread also over the Mountain Crimea.

Tuff layers were recognized in the uppermost Albian (Durnovarites prinflatum Su bzon e ), near the

Albian - Cenomanian boundary in Heu River and Baksan River in northern Caucasus. TheThickest tuff

layer was found in the Akusha and in some other sections of Daghestan (GORBUNOVA. 1966) It is close

to'the area of intensive Albian - Cenomanian intermediate to basic volcanism in the south slope of the

Great Caucasus There is an evidence that some volcanism was developed in the north-west Caucasus in

Phe tate ApUan time (Kornev. 1965) or. more likely, in the late Albian time. Unfortunately,

palaeontological data are very poor and could only be obtained from borehole cores.

The unique evidence of the existence of a tuff layer in the Peri-Caspian j SAS ONOVA & Sasonov

1967) is known in the uppermost Albian, near the Albian/Cenomaman boundary. In other^ sections, the

tuff layer is not preserved due to erosion at the beginning of Cenomanian time. It seems that the volcanic

ash source was the same as for the north-east Caucasus.

The maximum of the eustasy deduced from mountain Crimea and northern Caucasus series, correlate

with the position of the tuffs (Fig. 5). This is quite understandable, because voicanicevents were related

to (he rifting stage of Scythian Platform. For this reason, tuff layers do not exist on the Russian latform.

T h elauS fajT a rigidTsemen. was not affected by the movements of the north tethyan margm.

Hence, the appearance of tuffs in Peri-Caspian is occasional and was possibly due to aerial transport.

In contrast to the Scythian Platform. Mangyshlak - Great Balkhan region developed in a different

Crimea'c^casus-Ri^sian'Vlatfoum'regiorPas welf as'to that 'of the^Nortfi'^neri^continental margin

supposed have been connected with the Atlantic opening.

(ALEKSEEV, 1989). The volcanic ash sources were placed in the Small Caucasus voicam

104

EVGEN1J J. BARABOSHKIN ET AL.

collision volcanism occurred during Late Cretaceous time. The next volcanic event took place during

late Turonian on the Russian Platform (OLFERIEV data, unpublished). The sources of ashes were

probably the same as during the Cenomanian. It is puzzling that these bentonite layers are absent in the

southern area - Crimea and northern Caucasus.

Clay-rich beds, containing altered volcanic ashes (bentonites), are present in Turonian sediments of

the Munster Basin and Lower Saxony region of northern Germany. Analyse of these beds demonstrate

that it is possible to correlate individual bentonites and to use them as stratigraphical markers (WRAY et

al ., 1996).

Fig. 5. — Relative sea-level changes, main unconformities, anoxic events and position of volcanoclastic levels in Albian of

Crimea, northern Caucasus, Russian Platform. Mangyshlak - Peri-Caspian and Great Balkhan. Abbreviations in

columns mean names of ammonite zones/subzones and horizons illustrated on fig. 2. 1, sands, sandstones; 2, soft

sandstone / hard sandstone alternation; 3, silts, siltstones; 4, clays; 5. marls; 6. limestones; 7, shelly oolitic limestones;

8, tuff layers; 9. pebbles, conglomerates; 10. phosphorite pebbles and conglomerates; 11. flint levels; 12, cross -

bedding; 13. hiatuses; 14. eroded intervals, that could be reconstructed from fossil record in the basal horizons; 15,

erosional surfaces; 16, hard/softgrounds; 17. relative sea-level fluctuations of the 1th order; 18, relative sea-level

fluctuations of the 1th order for Peri-Caspian (only); 19. relative sea-level long-term fluctuations; 20, assumed relative

sea-level short-term fluctuations for reconstructed intervals; 21, anoxic and dysaerobic intervals.

Fig. 5.— Fluctuations du niveau marin. principales discordances, tenements anoxiques et position des niveaux volcano-

clastiques dans FAlbien de Crimee. du nord Caucase, de la plate-forme russe, du Mangyshlak, de la region peri-

Caspienne et des Grands Balkans. Les abreviations dans les colonnes correspondent aux zones / sous-zones d

ammonites et aux horizons de la fig. 2. 1, sables, gres ; 2. alternances de gres metibles et indures ; 3. limons.

microgres ; 4. argiles; 5. inames ; 6. calcaires ; 7, calcaires oolithiques coquilliers : 8. niveaux de tuff; 9, galets.

conglomerats ; 10, galets phosphates et conglomerats ; 11, niveaux siliceux ; 12. stratifications entrecroisees ; 13.

hiatus ; 14, intervalles erodes pouvant etre reconstruits a partir des fossiles dans les niveaux basaux ; 15, surface

d'erosion ; 16. surfaces durcies, surfaces meubles ; 17, fluctuations de ler ordre du niveau marin ; 18. fluctuations de

ler ordre du niveau marin pour la region peri-Caspienne : 19, variations a long terme du niveau marin ; 20. variations

a court terme supposees du niveau marin pour les intervalles reconstruits ; 21, intervalles anoxiques ou disaerobiques.

MID-CRETACEOUS EVENTS IN EASTERN EUROPE

105

Stratigraphic unconformities

Each of the studied sections reveals numerous stratigraphical gaps which differs in genesis and

morphology. The most complete succession is in the northern Caucasus - Crimea area, and the most

incomplete is in the Russian Platform.

We can divide stratigraphic gaps in several orders correspondingly to their significance and the area

of their development. In this paper we discuss only stratigraphic unconformities of the first order (SU-I).

which could be recognised for all of the mentioned regions. SU-I extents from one ammonite zone up to

a substage or even more. They were recognized almost in every region at the following levels.

Aptian/Albian boundary. Everywhere it is represented by a phosphorite conglomerate with reworked

Aptian/Albian fauna above an erosional surface (BARABOSHKIN, 1996). Probably the time of non¬

deposition corresponds to the Proleymeriella schrammeni Zone of Europe. The presence of the

Schrarmneni Zone in northern Caucasus (MIKHAILOVA & SAVELIEV, 1989) was not supported by the

new data. The lowermost Albian beds were recognised there in the Akusha section, where Leymeriella

( Leymeriella ) co-occurs with Hypacanthoplites. The hiatus corresponding to this SU-I varies from one

zone (northern Caucasus sections) up to two zones (Russian Platform and Peri-Caspian sections).

Basal part of the middle Albian. Phosphorite levels in the Eodentata and Lyelli Zones marked short

stops in sedimentation in the northern Caucasus. In the Mangyshlak - Peri-Caspian area and in the

Russian Platform this SU-I was “erased" in the S pathi Chron. during the sea-level rise. This led to the

strongest condensation of Albian sediments in the Moscow syneclize, with reworking ol the lower-

middle Albian ammonite faunas in a single horizon (BARABOSHKIN, 1996). In the Great Balkhan region,

this SU-I was not so significant, but the interval is marked by coarsening of sediments. It seems that this

SU-I appeared due to the influx of tethyan waters rather than of boreal ones. It is supported by finds of

tethyan ammonites Lyelliceras in northern Caucasus and Mangyshlak sections together with European

ammonites Hoplites.

Basal part of upper Albian. An erosional SU-I unconformity is characteristic for the Dipoloceras

cristatum Zone (= Semenovites tamalakensis Subzone of the Russian Platform - Mangyshlak).

An additional and stronger SU-I is recognised for the Hysteroceras orbignyi Zone. It was the time

when the low mountainous relief of the Crimea began to be covered by sea (digressive series). In the

Transcaspian area, it is marked usually by cutting and eroding of the sediments below, in the Russian

Platform - by the next stage of condensation.

The base of Mortoniceras inflatum Zone. This SU is recognized by the erosion in Mangyshlak -

Great Balkhan area (up to Intermedius Zone of the middle Albian), by phosphorite condensation in the

Russian Platform (including the whole lower - middle Albian in Ulianovsk section. Simbirsk Syneclise)

and by erosion in mountain Crimea. In the northern Caucasus this SU is recognised by the relative

coarsening of sections.

Base of Stoliczkaia dispar Zone. A SU-I is recognized by strong condensation in the Mangyshlak -

Great Balkhan area, and strong erosion in the Russian Platform. In mountain Crimea this SU was

reflected by erosion and deposition of conglomerate member (Yanin & Vishnevsky, 1989). Sections

of the central northern Caucasus are also marked by an erosional surface and phosphorite - belemnite

condensation (Kuma section). Even in Akusha section (the very complete one) sandy rocks were

deposited during this SU (BARABOSHKIN et al., 1997a).

Albian/Cenomanian boundary. This SU exists everywhere, but has a very variable morphology. It is

represented by erosional surface and phosphorite condensation in Crimea. In northern Caucasus three

phenomena express that SU: (a) erosion, (b) non-deposition and soft-ground development, and (c)

phosphorite condensation. Section-to-section those phenomena could be recognized in a 2-3 cm thick

interval. In other cases the last phenomenon completely reworked the previous ones. In the Russian

Platform and Peri-Caspian the boundary is marked by an erosional surface, and the hiatus is more

important, as a rule. The boundary SU is represented by condensed phosphorite horizon in Mangyshlak

and Great Balkhan area. The hiatus usually corresponds to one ammonite Zone, but in Tuarkyr (Akkyr

106

EVGENIJ J. BARABOSHKIN ETAL.

Mountains) it embraces the whole Stoliczkaia dispar Zone and the lower-middle Cenomanian. This SU

occurs also in Europe (England. France, Germany), Tunisia, and other regions.

A mid-Cenomanian SU is well recognised all over the studied area, but very variable in morphology

and the extent of the stratigraphical hiatus. In Crimea the SU is characterized by an erosional surface and

a hiatus shorter then one foraminiferal zone. In the North Caucasus mid-Cenomanian SU practically

exists in all sections, but the hiatus varies from a part of one zone up to the whole upper Cenomanian.

The mid-Cenomanian SU is well represented in the Russian Platform, Peri-Caspian region and

Mangyshlak basin, in the terrigenous facies. The phosphoritic horizon marks this SU and the hiatus

changes from of part of one bioslratigraphical zone to the all upper Cenomanian - lower Turonian

interval.

Cenomanian/Turonian boundary. A horizon of condensation or a submarine erosional surface is

sometimes situated at the Cenomanian/Turonian boundary. The duration of this hiatus corresponds to the

lower part or the whole Whiteinella archeocretacea Zone in Crimea and northern Caucasus. This SU

exist in the terrigenous facies of Mangyshlak, even in relatively complete sections. The appearance of

stratigraphic gaps could be controlled by short-term sea-level changes (Fig. 4).

DISCUSSION

The combined appearance of different events makes possible to formulate hypotheses about the

combined effect of different factors.

Tectonic movements

Tectonic subsidence rate is the main factor that determines the completeness of the sedimentary

record. This is well illustrated by comparison of northern Caucasus and mountain Crimea sections.

Aptian/Albian folding movements led drainage of the mountain Crimea, whereas the upper Albian

record in that part of the Crimea is much more complete. The rifting processes accelerated the

subsidence in the late Albian even in the mountains region. At the same time, northern Caucasus

successions were deposited in more stable conditions, far from the shore-line. This resulted in more

complete record, but delayed filling of the depressions.

Another effect of tectonic movements is the opening/closing of sea-way connections between

different basins (Baraboshkin, 1996). This led to the formation of numerous phosphorite levels in the

Russian Platform - Mangyshlak area, especially during the early - middle Albian, when cool water

penetrated from the Boreal Realm into the northern Tethys shelf area through a system of depressions on

the Russian Platform. In other regions, phosphorite horizons are less frequent and are not so rich in

phosphate. Local tectonic factors can also have a strong influence on the sedimentary conditions. Albian

through Turonian transition was characterized by global warming (REYMENT & BENGTSON, 1986) and

overall eustatic sea-level rise (Hancock & Kauffman, 1979; Haq et al., 1988). In the Albian of the

Peri-Caspian area, we have an opposite situation in terms of facies. According to us an activation of the

Hercynian basement during the Austrian compressional stage led to an accelerated denudation in the

south Urals (Mugodzhary) area and intensive deposition in the prograding delta system. This effect was

not so strong in the Mangyshlak-Great Balkhan of the Turanian Platform (TASHLIEV & TOVBINA, 1992),

because of the different tectonic position, and not so weak as for the northern Caucasus.

The Albian is characterized by an acceleration in tectonic activity. The Cenomanian-Turonian

interval is thus be largely controlled by the original basin geometry and eustatic changes. The effects of

local tectonics would be rather small though in some places the strata geometry has been influenced by

synsedimentary tectonics. In the Russian Platform local tectonics had only a minor influence on the

general composition of the studied successions, though the synsedimentary activity of the particular

blocks leads to the SU appearance.

MID-CRETACEOUS EVENTS IN EASTERN EUROPE

107

Volcanic events

Volcanic events are closely related with tectonic activity. They were initiated by the back-arc rifting

stage in the Crimea region and collisional volcanism in the Small Caucasus region. Volcanic

sedimentation strongly affected the depositional system, having the avalanche type in the volcanic area.

It leads to the intensive water exchange. Probably this was the main reason for the absence of anoxic

Albian sediments in the plain Crimea in opposite to the northern Caucasus.

Sea-level fluctuations

Another important factor are long- and short-term sea-level fluctuations. All of the anoxic beds are

located in the deepest parts of basins and their appearance was controlled by the first order sea-level

changes. This is one of the main reasons, why the strongest anoxic conditions developed during upper

Albian time in northern Caucasus: this was the time of a long-term eustatic rise. In other regions it was

too shallow for anoxia development (mountain Crimea and Russian Platform) or the relative sea-level

trend had an opposite direction. It could be possible when the rate of the tectonical uplift is higher than

the rate of the eustasy. Short-term sea-level changes controlled the appearance of stratigraphic gaps in

the successions.

Several recent publications deal with the sea-level curves during Aptian - Cenomanian times

(ALEKSEEV et ai, 1996) and Bajocian - Santonian times for the Russian Platform (SAHAGIAN & JONES,

1993; SAHAGIAN et ai, 1996). The former authors are very close to our point while one of the latter

publications has been criticized (Naidin & Baraboshkin, 1994).

Climatic changes

General climatic changes were reflected in the facial record. Almost everywhere in the studied area

Albian - lower Cenomanian succession exists in terrigenous facies. Exclusively carbonate deposition

took place there since the late Turonian time. An expansion of the warm climate and Tethyan water was

the main cause of the depositional break: carbonate sedimentation starts in the early Cenomanian in

Crimea, in the middle-late Cenomanian in the northern Caucasus. Carbonate sedimentation appears only

in the late Turonian time in the central parts of the Russian Platform, Peri-Caspian and Mangyshlak

basins.

The Cenomanian, lower and middle Turonian ammonite assemblages of Mangyshlak and the Peri-

Caspian Basins are dominated by hoplitids, schloenbachiids and acanthoceratids of European type

(Marcinowski et ai, 1996). Heteromorph ammonites, puzosiids, phyllo- and lytoceratids were

observed with European forms in the Crimea and northern Caucasus area. This suggests the existence

here of deep offshore environments. Foraminiferal assemblages confirm that in Crimea and Caucasus

the Cenomanian - Turonian succession contains a significant quantity of planktic foraminifera (about

50-75%). At the same time, Mangyshlak, Peri-Caspian and Russian Platform successions contain

assemblages where benthic forms prevail (about 90%: Kopaevich, 1989).

Massively ornamented forms are noted within terrigenous facies of the lower and middle Turonian of

Mangyshlak. The late Turonian change of the ecomorphic characteristics in ammonites reflects the

relative deepening of the basin and the appearance of carbonate sediments (MARCINOWSKI et al ., 1996).

In this interval the ratio planktic/benthic foraminifera increases also. Thus, the fluctuations of the

ammonite and foraminifera assemblages can be described to some environmental conditions

(bathymetry) rather than to climatic one.

108

EVGEN1J J. BARABOSHKIN ETAL.

CONCLUSION

Examination of different event data from the Russian Platform and adjacent areas to the south

demonstrate that most of the events were occurred during brief time spans and furthermore did not

appear simultaneously. The main causes originating the events were tectonics and sea-level fluctuations

forced by climatic changes. Various combinations of these factors and their consequences resulted in the

general style of sedimentation (i.e. palaeogeography) and completeness of geological record.

ACKNOWLEDGMENTS

Authors are grateful to Peri-Tethys Program (Grants N° 95/43 and 95-96/43), Programme IGCP 362,

1NTAS (Grant N° 94-1805) and RBSF foundation (Grants N°95-07-19015, 96-05-657339 and 97-05-

567) for the financial support of the investigations.

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Evolution of the eastern Fore-Caucasus basin

during the Cenozoic collision: burial history

and flexural modelling

Andrei V. ERSHOV ", Marie-Frangoise Brunet 21 ,

Anatoly M. Nl KISH IN' 11 , Sergey N. BOLOTOV 0 ',

Maxim V. KOROTAEV 01 & Svetlana S. KOSOVA ,3>

Geological Faculty. Moscow State University, Vorobievy Gory. 119899 Moscow, Russia

'' CNRS ESA 7072. Universite Pierre et Marie-Curie, case 129. 4 place Jussieu, F-75252 Paris Cedex 05, France

Central Geophysical Expedition. Moscow, Russia

ABSTRACT

The Late Cenozoic evolution of the eastern Fore-Caucasus molasse basin was controlled by the collisional history of the

Caucasus segment of Alpine-Himalayan fold bell. There are two main stages of syncollisional evolution of the basin: (I) 34-

15.8 Ma (Maikopian stage) - “soft” collision in the area of Lesser Caucasus, simultaneously with a rapid subsidence of a broad

area which could be caused by flow in the mantle induced by a modification in the subduction regime (rotating down of the

slab); and (2) 15.8-0 Ma - collisional climax, Great Caucasus orogenesis, accompanied by formation of the molasse basins. This

paper presents the mean results of backstripping of 129 wells, a 2D burial history along a seismic section and a 2D flexural

model for the eastern Fore-Caucasus molasse basin during the second stage of syncollisional evolution. During the first

(Maikopian) stage, investigated basin underwent rapid long wavelength subsidence, nearly homogeneous in the investigated

basin, slightly increasing to the south. Palaeowater depths were near 500-800 in the central part and reached 1200 m at the

southern edge (estimation proposed with the technique of palaeobathymetric restoration from the shape of clinoforms

accounting for the compaction of sediments and regional isostatic compensation). Two-dimensional restoration of the evolution

shows the presence of a post-Maikopian uplift, visible by an important erosion in the north of the basin. Two-dimensional

flexural modelling demonstrates that observed subsidence of this area at late Miocene - Quaternary time can be explained by an

effect of the elastic flexural response of lithosphere, with EETnear 60 km. to the loading in the area of Great Caucasus orogen.

Ershov. A. V.. Brunet. M.-F., Nikishin, A. M., Bolotov, S. N„ Korotaev, M. V. & Kosova, S. S„ 1998. — Evolution

of the eastern Fore-Caucasus basin during the Cenozoic collision: burial history and flexural modelling. In: S. Crasquin-

Soleau& E. Barrier (eds), Peri-Tethys Memoir 4: epicratonic basins of Peri-Tethyan platforms, Mem. Mus. now. Hist. not..

179 : 1 11-130. Paris ISBN : 2-85653-518-4.

Source: MNHN, Paris

1 12

ANDREI V. ERSHOV ETAL.

RESUME

Evolution du bassin du Pre-Caucase oriental durant la collision Cenozoique: histoire de I'enfouissement et

moderation flexurale.

L'evolution fini-Cenozoique du bassin molassique d'avant-pays du Caucase oriental a ete controlee par I’histoire dc la

collision du segment caucasien de la chaTne Alpes-Hintalaya. L'histoire syncollision du bassin comprend deux etapes: (I) 34-

15.8 Ma (stade Maikopien) - debut de la collision dans la zone du Petit Caucase, simultanement avec une subsidence rapide

d'une large zone qui pourrait etre due a des mouvements niantelliques induits par une modification du regime de subduction

(rotation du “ slab ” vers le bas); (2) 15.8-0 Ma - climax de la collision, orogenese du Grand Caucase, accompagn^e de la

formation de bassins molassiques. Ce papier presente les resultats moyennes du ''backstripping" de 129 forages, une

reconstitution 2D de l'histoire de I’enfouissement le long d'une section sismique et un modele flexural 2D pour la portion

orientale du bassin molassique d'avant-pays du Caucase pendant le second stade de revolution syncollision. Durant le premier

stade (Maikopien), le bassin etudie a subi une subsidence rapide de grande longueur d'onde, assez homogene dans I’ensemble

du bassin. et s'accroissant legerement vers le sud. Les paleoprofondeurs etaient proches de 500-800 m dans la partie centrale et

atteignaient 1200 m dans la partie meridionale (estimation proposee en utilisant la technique de reconstitution

paldobathymetrique it partir de la forme des “ clinoformes ” tenant compte de la compaction des sediments et de la

compensation isostatique regionale). La reconstitution en deux dimensions de revolution met en evidence la presence d'un

soulevement post-Maikopien visible par une erosion importante au nord du bassin. La modelisation flexurale bi-dimensionnelle

montre que la subsidence observee dans cetie region au Miocene superieur - Quaternaire peut etre expliquee par un effet de

reponse flexurale elastique de la lithosphere a la surcharge de l’orogene du Grand Caucase, l'epaisseur elastique equivalente

etant proche de 60 km.

INTRODUCTION

The Caucasus region is a part of the Alpine-Himalayan orogenic belt, located between the Black Sea

and the Caspian Sea. Tectonically, it can be subdivided into: the Great Caucasus orogen, the western

(Indol-Kuban) and eastern (Terek-Caspian) Fore-Caucasus molasse basins (to the north of Great

Caucasus), which are separated by the basement uplift (the Stavropol High), and. finally, the western

(Rioni) and the eastern (Kura) Trans-Caucasus molasse basins (to the south of Great Caucasus) (Fig. 1).

The area of the eastern Fore-Caucasus molasse basin is well studied. It is a productive oil province

with many wells and seismic sections. Extensive literature describes the geology of this region, mainly

in Russian. The stages of geological history and the reconstruction of palaeogeography and

palaeotectonics are presented briefly in NIK1SHIN et at. (1998a-b).

In contrast to the geological studies, only a few numerical geodynamical models have been made.

ARTEMIEV & BalavaDZE (1973) presented an analysis of isostatic anomalies of the Caucasus region.

Ruppel & McNutt (1990) analyzed gravity anomalies in the framework of the model of elastic flexure

and reconstructed the flexural rigidity of the lithosphere. MIKHAILOV (1993) made a 2D kinematical

restoration and palaeotectonical analysis for the evolution of the Terek-Caspian trough. BOLOTOV

(1996) calculated 129 subsidence curves for wells located in the eastern Caucasus molasse basin.

In this paper we present 1D and 2D burial history models of the eastern Fore-Caucasus molasse

basin. The results of the kinematic restoration form the basis for flexural modelling.

GEOLOGICAL DATA

This region has for a long time been the object for oil production. Existing data (network of seismic

sections, more than thousand wells, heat flow data and gravity data) provide a good basis for modelling.

Our kinematic restoration of burial history of the basin was made on the basis of one seismic section and

more than one hundred wells, which were averaged to produce a statistically mean burial history for the

whole basin.

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

113

44°

46°

48°

44°

42°

Fig. 1.— Schematic map of investigated area, backstripped wells, seismic section (black line) and synthetic section (grey line).

The location of backstripped wells is shown by the open circles (one circle may represent a set of wells in its area). The

closed circles show location of wells presented on the figure 5: 1, Zapadno-Aksaiskaya-3. 2, Tarumovskaya, 3,

Vostochno-Ozernaya, 4. Profilnaya-8.

Fig. /.— Carte schematique de la zone d'etude : forages , section sisrnique (ligne noire) et section synthetique (ligne en grise).

La localisation des forages etudies par la methode de backstripping est indiquee par des cercles (un cercle pent

representer un ensemble de forages). Les cercles pleins montrent la localisation des forages presentes stir la figure 5 :

I. Zapadno-Aksaiskaya-3. 2. Tarumovskaya. 3. Vostochno-Ozernaya. 4. Profdnaya-8.

Crustal structure

The eastern Fore-Caucasus basin is the eastern part of the Scythian Platform which is situated

between the Russian Platform and the Great Caucasus, the Crimean and the Carpathian orogens. The

basement of the Scythian Platform is Hercynian in age (Letavin, 1980). The main source of

information about crustal structure of the region is the deep seismic sounding section Volgograd-

Nakhichevan. crossing the eastern part of Caucasus orogen and molasse basins, which was used to

produce a crustal section of the investigated region (Fig. 2). The location of this synthetic section (grey

line on Fig. 1) is close to the location of the modelled seismic line (black line on Fig. 1) in the northern

Fore-Caucasus basin. Geophysical processing of this crustal section was done by Krasnopevtseva

( 1984). Unfortunately we do not have new high resolution deep seismic data in this region, details of

crustal structure under the Great Caucasus orogen and in the Trans-Caucasus areas are not

discriminated. Upper part of the section is constructed on the basis of geological data resulting from

field observations in orogenic area, and from seismic and well data in the basins.

We can characterize four layers in the section of the Scythian Platform on the basis of seismic data.

(1) Jurassic-Quaternary sediments; (2) Palaeozoic (Hercynian) basement with Triassic inclusions

ANDREI V. ERSHOV F.TAL.

I 14

(seismic velocities 5.3-5.8 km/sec); (3) Precambrian folded rocks with seismic velocities 6.0-6.6 km/sec

and (4) lower crust with seismic velocities 6.8-7.2 km/sec. The crust below the Scythian platform is

about 40 km in thickness and it thins below the Terek-Caspian basin to about 30 km.

South

Kura Basin

Position of the modelled seismic section

I-1

Terek-Caspian Manych Karpinsky

basin trough swell North

304125

7.2

500 600 700 km

J-1-1

Great Caucasus

orogen

km -

200

400

Sediments Basement

14 Pliocene-Quaternary Ejjtl Jurassic - Eocene [y. j Paleozoic |yj Lower Crust Higher density zones Faults

I 1 Oligocene- Miocene H Triassic GD Precambrian |_| ^ndwided ^ Lo wer density zones

FiG. 2.— Crustal scale synthetic section through the eastern Caucasus and adjacent sedimentary basins. Position of the synthetic

section is shown on the figure 1 (grey line). The section is drawn on the basis of deep seismic section Volgograd-

Nakhichevan (based on the interpretation of Krasnopevtseva. 1984). Upper part is constructed on the basis of field

geological data in orogen areas, and of seismic and well data in basins areas.

Fig. 2 .— Section crustale synthetique a travers le Caucase oriental et les bassins sedimentaires adjacents. La position de la

section synthetique est ituliquee stir la figure I (ligne grisee). La section a etc construite sur la base de la section de

sismique profonde Volgograd-Nakhichevan (basee sur /'interpretation de Krasnopevtseva. 1984). La partie superieure

est construite sur la base des donnees geologiqties de terrain dans les zones orogeniques et des donnees de sismique et

de forages dans les zones de bassins.

Palaeozoic rocks are penetrated by the wells in the areas of the Karpinsky swell and the Kuma High

(Letavin, 1980); this layer thins towards the Great Caucasus. To the north, the bottom ot this layer is

correlated with the bottom of Palaeozoic sediments (or with top of crystalline basement) on the Russian

Platform (KRASNOPEVTSEVA, 1984). On the deep seismic section Stepnoe-Bakuriani

(Krasnopevtseva, 1984, just to the west of our section, not presented here) it is possible to trace the

third seismic layer to the surface, where Precambrian crystalline, metamorphic schists, gneisses and

Hercynian granitic intrusions are outcropped.

Sedimentary data

As a basis for the modelling we have chosen a seismic section traversing the main tectonic units ot

the eastern Fore-Caucasus molasse basin: the Karpinsky swell, the east-Manych basin, the Kuma High,

Source : MNHN , Paris

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

1 15

F,G 3.— Geological section constructed on the basis of regional seismic section V (black line on Fig. 11)i and well data

(exaggeration 110)- fragment of the seismic section (horizontal scale in kilometers, vertical scale seconds two-way

travettime); numbers 1-4 near the wells denote wells presented on the Fig. 5. The numbers on the sections correspond

to units: 1. Quaternary; 2. Akchagylian; 3. Pontian; 4. Meotian; 5. Sarmatian; 6. Chokrakian-Karagaman. 7. Maikopian.

8. Palaeocene-Eoeene; 9, Cretaceous; 10. Jurassic.

Fir ? Coune eeoloeiaue construite d'apres la section sismique regionale V (ligne noire Fig. II et les donnees de forages

^ ^exag/radon tiW) 6 ; ‘fragment de la section sismique f ,fchelle horizon,ale en kilometres, echelle verncale en secondes

temps double) ; les chiffres 1-4 situes a cote des forages indiquent les forages presents dans la figure 5 Les t nft -

surYes sections correspondent aux unites : I. Quaternaire ; 2. Akchagylten ;3 Pontten : 4. Meotien . 5. Sauna,ten . 6.

Chokrakien-Karaganien : 7. Maikopien : 8. Paleocene-Eocene : 9. Cretace ; II). Jurasstque.

Source: MNHN. Paris

1 16

ANDREI V. ERSHOV ETAL.

the Terek-Caspian basin_(Fig. 1). A geological section based on seismic data and a portion of the seismic

section are presented on figure 3. We have used the seismostratigraphical interpretation of eastern

Caucasus seismic sections made by KUNIN et al. (1990). The section contains three complexes with

clinoforms: one each in the lower-middle Maikopian (unit 7), the Sarmatian (5) and the Akchagylian (2)

sedimentary complexes. Buried erosional relief is present in the northern part of the section. A detailed

seismostratigraphical interpretation of this seismic section, representative of the basin subsidence

history, was used to produce a 2D burial history of the basin. Wells situated along the profile were used

to validate geological interpretation of the seismic line.

It is difficult to correlate the regional stratigraphic units with the global time scale for the late Eocene

- Quaternary time, because a common time scale does not exist for the northern intercontinental basins

of Tethys during the Middle-Late Cenozoic time. The use of palaeomagnetic data is problematic because

of lack of some parts of section (in the stratigraphical sense), due to numerous erosional events.

For an absolute dating of Maikopian units (Oligocene-early Miocene), we have used the

biostratigraphical scale based on the micropalaeontological zonation correlated with mediterranean time

scale (POPOV et al., 1993). The early Maikopian part of section is composed by the clinoform bodies. To

define time span of deposition of each clinoform. we use the calculations based on the analysis of the

total 3D volume of each clinoform (reconstructed from seismic network) and the hypothesis that the rate

of clastic material input was constant through time (KUNIN et al., 1990). For late Miocene-Quaternary

(13.7-0.5 Ma). the radiometric dating of Chumakov (Chumakov et al., 1992: Chumakov, 1993) was

used. It is based on the analysis of' "U fission tracks in volcanic glass from tuffs.

These datations as well as seismic and well data were used to construct a chronostratigraphical chart

(Fig. 4) of the basin. The seismic section was used to show general architecture of the basin. Wells

situated along seismic line gave informations on the lithological composition and stratigraphy of the

basin. It is also shown a comparison of regional units with time scales of HARLAND et al. (1989) and

Odin (1994). Scale of Odin (1994) was used in the modelling. These scales are close for Middle and

Late Cenozoic times. In general, lithological composition of the Oligocene-Quaternary sediments is

represented by two distinct complexes. The lower complex (Maikopian-Tarkhanian) is composed by

thin clastic sediments (clays and siltstones with rare sandstone lenses). The upper one (Chokrakian -

Quaternary) contains mainly limestones, sandstones, marls, siltstones and conglomerates. The Meotian-

Pontian part of the section contains numerous unconformities corresponding to hiatuses and erosional

events in the basin history during which a part of sediments was removed on the northern side of the

section.

SUBSIDENCE EVOLUTION OF THE FORE-CAUCASUS BASINS

ON THE BASIS OF BURIAL HISTORY RESTORATION

Method

A standard backstripping technique

(Steckler & Watts, 1978)was used to restore

ID burial histories. The compaction correction

was made according to the porosity-depth

dependencies, which were calculated using

published porosity data for western Caucasus

basin (AVCHYAN & OZERSKAYA, 1985). We

have supposed an exponential compaction law

for five standard lithological types (clay,

siltstone, sandstone, limestone and marl) and

used least-square fit to obtain statistically

averaged compaction dependencies. Obtained

parameters of exponential porosity-depth

relationships are presented in Table 1.

Table I.— Parameters in exponential porosity-depth

dependencies for basic lithotypes, obtained by the

least-square fitting of measured porosities in the

western Caucasus basins (data from Avchyan &

OZERSKAYA, 1985); f=fe ' ,c ; f, porosity at depth z; f -

surface porosity; c, scale factor.

Table I .— Parametres de dependance exponentielle de la

porosite avec la profondeur pour les lithologies de

base, obtenus par un ajustement (methode des

moindres carres) aux porosites mesurees dans les

bassins situes dans la parlie occidentale du Caucase

(d'apres les_donnees de Avchyan & Ozerskaya,

1985); f=fe ' Jc . f porosite d la profondeur z. f o

porosite de surface, c. facteur d'echelle.

Lithotype

Surface Porositv (%)

Scale Factor (km)

Clay

3.9

Sandstone

6.4

Marl

3.6

Limestone

2.6

Siltstone

4.7

Source: MNHN. Paris

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

1 17

Fig. 4. — Chronostratigraphical chart along seismic section (black line. Fig. 1). time scales of Harland el al. (1989) and Odin

(1994), datations of Chumakov et al. (1992). Legend: 1. sandstones; 2. clayey-sandstones; 3. siltstones; 4. clays: 5.

clayey siltstones and limestones; 6, sandy limestones; 7. clayey limestones: 8. limestones: 9. organogenic detritic

limestones; 10. underwater hiatus due to uncompensated sedimentation; 11. eroded rocks; 12. hiatus.

Fig. 4.— Charte chronostratigraphique le long de la section sismique etudiee Iposition ligne noire, Pig. 1). echelles des temps

de Harland et al. (1989) et Odin (1994). dotations de Chumakov et al. (1992). Legende : I. gres : 2. gres argilenx : J.

silts ; 4. argiles ; 5. silts et calcaires argilenx : 6. calcaires sableux : 7, calcaires argilenx ; 8. calcaires ; 9,calcaires

organogenes detritiques ; 10. hiatus sub-aquatique du a une sedimentation non compensee ; 11. roches erodees : 12.

hiatus.

Source: MNHN, Paris

ANDREI V. ERSHOV ET AL.

Subsidence curve of one well is often reflecting local tectonic or sedimentation conditions and often

may not be a good representative of whole region. We use data and results alter the work of BOLOTOV

(1996) who calculated subsidence curves on 129 wells in the Fore Caucasus basin. From these data, we

have computed an average subsidence curve of the basin. Whole time interval was subdivided into

subintervals so that any boundary present in any well was present also in the average curve. For each

time span, in this subdivision, the rates of tectonic subsidence and basement subsidence were averaged

only for the wells really penetrating this interval of the section. After that the tectonic subsidence and

basement subsidence were found by an integration of corresponding rates.

Palaeobathymetric and sea level corrections are not performed on the 1D tectonic subsidence curves

due to poor knowledge of absolute values of sea level variation and palaeobathymetry. Knowing also

that there were 3 main periods of clinoformal sedimentation, during the Maikopian, the Sarmatian and

the Akchagylian, sedimentary thicknesses and palaeobathymetries might be very different from one

point to another one and rapidly changing with time. Consequently the changes in tectonic subsidence

rates (Figs 5, 6) are the results of a combination of tectonics and conditions of sedimentation. We have

restored palaeobathymetries for clinoformal stages in 2D case when it was possible.

To make 2D reconstructions, the section was subdivided into a set of pseudowells and ID

reconstructions were made for each pseudowell, then the section is reconstituted through time with

sediments decompacted and palaeowater depths. The main difficulty is the estimation of the

palaeobathymetry/palaeotopography. An estimation can be attempted for the clinoformal stages

(Maikopian. Sarmatian. Akchagylian) as geometrical shape of clinoforms is correlated with

palaeobathymetry. A special algorithm was used to reconstruct palaeobathymetry from the shape of

clinoforms allowing to take into account correction for the compaction and regional isostasy.

The clinoform has two parts: shelf and slope. The shelf part is near the sea level during deposition.

The problem is to restore palaeobathymetry of the clinoform slope and of the bottom of the deep-water

non-compensated basin, not covered by sediments. During its deposition, a clinoform fills the

accomodation space created by the subsidence before and during deposition and also by the variation of

sea level. We cannot discriminate a general subsidence from a sea level variation and later we will say

subsidence, meaning subsidence or sea level variation or their combination. If we can discriminate the

subsidence which was existing before from the subsidence during deposition, then we will be able to

restore palaeobathymetry. Subsidence appeared during clinoform deposition contains tectonic

component and component due to loading of clinoform itself. For the simplicity, as a first order

approximation, we suppose that tectonic component of subsidence during deposition is constant or

proportional to the total thickness of whole layer composed by the clinoforms, along the horizontal axis.

In this case we can define it from the thickness of the shelf part of following clinoform which is

overlapped by shelf parts of preceding one, because bathymetry of shelf part is known.

Let us suppose that the bathymetry of the layer deposited after a considered clinoform is known.

Then we can restore the bathymetry during the deposition of clinoform by subtraction of thickness of

above layer from its bathymetry and adding tectonic and isostatic components of subsidence during

deposition of the clinoform. Starting from the layer with known bathymetry (it may be layer of the end

of clinoformal stage when all the basin is filled by the sediments) we can subsequently restore

palaeobathymetry for each clinoform backstripping them step by step and performing corresponding

corrections for the compaction, subsidence/sea level variation during the deposition of the clinoform and

isostasy. We have performed such procedure for the Maikopian and the Akchagylian stages, using

regional isostatic corrections (EET: 60 km).

On the modelled section some layers in the northern part are partly removed due to erosion. The

thicknesses of eroded parts of these layers were restored by the interpolation of thickness of remaining

parts. The interpolation was performed for the Maikopian, the Chokrakian and the Sarmatian layers.

Results

The burial histories of four selected wells along the studied section are presented on figure 5. The

location of these wells is shown on figure 1 and on the section on figures 2 and 3. A statistically

averaged burial history of the basin is presented on figure 6, after the work of BOLOTOV (1996) on the

Source: MNHN, Paris

KVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

1 19

Geological time (Ma)

s - j

•8

I -

(/)

5 -

(4) Profilnaya-8 well

150 -

2 100 :

■IG. 5.- Burial history (basement subsidence [curve 1), tectonic subsidence (air-loaded, p„,=3.3 g/cm’) [2] and ratej of tectonic

subsidence [3]) for 4 selected wells near the seismic section stuuied in eastern Fore-Caucasus basim 1 Zapadno-

Aksaiskaya-3.2 Tarumovskaya, 3 Vostochno-Ozemaya. 4 Protilnaya-8. Location of wells is shown on the figure 1 by

the closed circles with numbers and on the figure 3. Lower part of Zapadno-Aksaiskaya well is synthetic, constructed

on the basis of seismic section.

■ IG . 5.- Histoire de l'enfouissemeni <subsidence du socle Icourbe I], subsidence technique (a Lair

mux de subsidence tectonique 13]) pour 4 forages procl.es de la section ^Zsi^n dL forages

Caucase 1 Zapadno-Aksaiskaya-3, 2 Tarumovskaya. 3 Vostochno-Ozemaya, 4 Profilnaya-8. La post ion des forage i

est montree sur la figure I par les cercles pleins name rotes el sur la figure 3. La partie infer, cure du forage Zapad

Aksaiskaya est synthetique, construite d'apres la section sismique.

c '50:

t3 ioo :

(3) Vostochno-Ozemaya

s 1504

2 100 :

50 :

(2) Tarumovskaya well

0 Zapadno-Aksayskaya-3 well

120

ANDREI V. ERSHOV ETAL.

Geological Time (Ma) Geological Time (Ma)

300 250 200 150 100 50 0 40 30 20 10 0

Fig. 6.— Burial history (basement subsidence and rate of tectonic subsidence) averaged for 129 wells (after Bolotov, 1996) in

the eastern Fore-Caucasus basin (location of wells is shown on figure 1). a) for Permian-Quatemary time interval, b)

more detailed for end of Eocene-Quaternary interval (time scale of Harland et al. (1989)). The grey areas indicate

periods of increased subsidence rate discussed in the text.

Fh;. 6.— Histoire de I'enfouissement (subsidence du socle el laux de subsidence tectonique), moyennee pour 129 forages

(d'apres Bolotov. 1996) dans le bassin oriental du Pre-Caucase (la position des forages esi montree stir la figure I).

a) pour I 'intervalle de temps Permien-Quaternaire. b) avec plus de details pour Pintervalle de temps fin de V Eocene-

Quaternaire (echelle des temps de Harland et al. ( 1989). Les zones en grise indiquent les periodes d’augmentation du

laux de subsidence discutees dans le texte.

subsidence curves of 129 wells, using the time scale of Harland et al. (1989). Subsidence curves for

Permian-Quatemary time interval are shown on figure 6a ; figure 6b presents a portion of the figure 6a

for the end of Eocene-Quaternary interval. Chronostratigraphical chart (Fig. 4) and two-dimensional

(Fig. 7) along the seismic section (black line, Fig. 1) illustrate the 2D late Palaeogene - Neogene burial

history of the basin. As our main subject is Late Cenozoic history of the basin we will describe previous

stages only briefly.

The Mesozoic history of the basin started with Triassic riftogenesis and subsidence of the whole

basin during postcollisional relaxation of Late Palaeozoic Scythian orogen (NlKlSHlN et al., 1998b). The

Triassic history is not well known because the most part of Triassic sediments was removed during

orogeny in Late Triassic - Earliest Jurassic and only some remnants of deformed Triassic sediments are

preserved. Next major subsidence event occurred during the Middle - Upper Jurassic (Figs 5, 6) as a

result of rifting with maximum of extension located in the area to the south, which led to formation of

the Great Caucasus basin (NlKlSHlN et al., 1998a-b). During the remaining of Cretaceous and

Palaeocene-Eocene, investigated region was a part of the shelf basin of the East European Platform

opening into the deep-water Great Caucasus basin (SCHERBA. 1993). A decrease of the subsidence is

observed at this time (Figs 5, 6). Such quiet and decreasing subsidence is characteristic for the postrift

basins and we speculate that this subsidence was caused by the thermal cooling of lithosphere.

At the end of Eocene, sediments were deposited in shallow water environment (Koronovsky et al.,

1987). The Eocene/Oligocene boundary is pointed by a fall of the eustatic sea level which caused a

separation of the northern part of Tethys named Paratethys (Baldi, 1980). At the same time, in the

eastern part of Paratethys, a specific deep water Maikopian basin was formed. Subsidence of the basin

Source: MNHN. Paris

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

121

was nearly homogeneous with a slight tilting towards the south (Fig. 7A-D). Water depth estimations are

ranging from 500 to 1000 m, on the basis of palaeontological criteria (Scherba, 1993). Our estimations

based on the shape of clinoforms (as it is described above) give values 500-800 m in the central part ot

the modelled section and up to 1200 m in its southern part (Fig. 7A-B). During the early and middle

Maikopian time, the basin was filled by clinoforms prograding from the north-east (Fig. 7A-B) and later

the basin continued to subside (Fig. 7 C). In the early Miocene, after filling of the basin by sediments,

the palaeowater depths were not deep in the investigated area. From a total amount of near 2 km ot the

Maikopian subsidence, approximately 1.3 km is induced by loading ot sediments and 0.7 km is of

tectonic origin.

On the basis of analysis of subsidence curves and 2D restoration, we can separate two mam stages in

the Oligocene-Quaternary evolution of the basin: an Oligocene-early Miocene (34-15.8 Ma)

(Maikopian) stage and a late Miocene-Quaternary (15.8-0) (orogenic) stage. The latter stage began with

a short Chokrakian-Karaganian (15.8-15 Ma) event of rapid subsidence (Figs 5, 6). Another event ot

high subsidence rates took place in the middle-late Sarmatian (12.2-9.3 Ma) (Figs 5, 6). It was coeval

with significant changes in the palaeogeography, when the eastern segment of the Great Caucasus

orogen was exposed palaeogeographically as a continental area, tans ot conglomerates and reets were

formed on the periphery of The orogen (KORONOVSKY et ai, 1987). In plane configuration of the basin

was changed (Nevesskaya et ai, 1984), shape of the basin became asymmetrical with deepening

towards the orogen (Fig. 7 D-E).

The Meotian-Pontian-Kimmerian time is characterized by alternating periods ot opening and closing

of the eastern Paratethys and associated variations of sea level (NEVESSKAYA etai, 1984). During most

of this time the basin was in continental conditions and periods ot sedimentation were interlaced with

erosional periods (Fig. 4). Thicknesses of Meotian-Pontian sediments are small (Figs 3 7 F) they are

composed mainly by clastic material (Fig. 4) which was transported by slope sliding from the Great

Caucasus orogen. The most significant fall of sea level occurred in the middle-late Pontian (6.5-5.6 Ma)

and led to separation of the Palaeo-Caspian sea from the Palaeo-Black sea (Nevesskaya et ai, 984 .

This event is correlated with the Messinian event in the Mediterranean sea (CHUMAKOV, 1993).

Kimmerian (5.2-3.4) sediments are absent everywhere in the basin (Fig. 4).

Small thicknesses of the Meotian-Pontian sediments can be explained either by the small subsidence

at this time or by the small input of clastic material from the Caucasus. The Meotian and Pontian

sediments have a shape similar to clinoform, but as sedimentation occurred in continental conditions by

slope sliding its upper part is not necessarily horizontal and may be inclined. Even it we suppose that

inclination is small (basing on the small rate of sedimentation) we can restore palaeotopography only at

the southern part of the section as its northern part is eroded. The only possible thing is to restore Pre-

Akchagylian topography. The rapid rise of sea level in the Akchagylian (3.4-1 8 Ma) led to the

clinoformal sedimentation, when clinoforms filled the accommodation space created betoie (Fig. / G-

H). We can suppose different ways of subsidence before Akchagylian: either the accomodation space

filled by the Akchagylian clinoform was created just before the Akchagylian as a result ot abrupt

tectonic processes or it was formed continuously during the Meotian-Pontian-Kimmerian due to

gradually increased loading of Caucasus. Data do not allow to discriminate between these two

hypotheses.

To the north of the niolasse basin a peripheral bulge uplifted and this uplilt led to the erosion ot the

northern part of the section (Figs 4, 7 F-G). We cannot discriminate the time ot beginning of uplift as

related part of the section is removed. It is possible only to say that it began not in Maikopian but

probably after Chokrakian. as thicknesses of these layers are constant on the most part ot the section and

not decreasing gradually but sharply truncated by the erosional boundary. The amplitude ot the erosion

in the northernmost part of the section is more than 1 km and the erosion had lasted some time to be able

to remove such large amount of sediments, therefore uplift began at least several million ot.years be ore

the Akchagylian when sediments covered the erosional palaeoreliet (Fig 7 H). buch logical

argumentation allows us to put beginning of uplift into Sarmatian-Pontian interval ol time.

In the Quaternary the whole basin, including its northern flank, has subsided and was covered by

sediments (Fig. 7 I). The Late Quaternary is characterized by a fall of sea level and now the basin is in a

continental environment.

122

ANDREI V. ERSHOV ET AI-.

Water

Fig. 7.— 2D burial history restoration along the section (black line. Fig. 1) shown on figure 3. The chronostratigraphical chart

along the section is shown on figure 4; selected time slices for Oligocene-Quaternary (34-0 Ma).

Fig. 7.— Reconstitution de I'histoire de I'enfouissement en 2D le long de la section (ligne noire, Fig. I) presenteesur la figure

3. La charte chrondstratigraphique le long de la section est montree sur la figure 4 ; etapes selectionnees dans

I’intervalle de temps Oligocene-Quaternaire (34-0 Ma).

GEODYNAMICAL MODEL

Late Cenozoic geodynamics of the Fore-Caucasus basin is a part of collisional dynamics of a more

general region. The collisional history of the Caucasus region is not well constrained by data yet and

several different interpretations exist (e.g. KORONOVSKY et al., 1987; BELOV & SATIAN, 1989;

DERCOURT et al., 1993; ZONENSHAIN et al.. 1990). Here we follow the recently published interpretation

of NlKISHIN et al. (1998a-b). A scheme, illustrating the collisional history of Caucasus and giving the

geodynamic context of the area through time, is presented on the figure 8.

Source. MNHN, Paris

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

123

Present time

0 25 50 75 100 km

Middle Jurassic - Eocene

Oiigocene -Early Miocene (Maikopian)

Late Miocene - Quaternary

Water

The Great Caucasus polyphase orogeny started at the Eocene/Oligocene boundary In the Eocene

(pre-coll^^nal'tim^a^eep^water basin T/al. 1 ! l^l))! ^HhestTbasins

ef a a/ S * t 'l^93) t0 At e ,ke ll Eocene/OlfgoceM 1 boundary" the°north-dipping subduction was changed into

Source

124

ANDREI V. ERSHOV ETAL.

Transcaucasus region, thrusting along the northern margin of the Great Caucasus trough (MlLANOVSKY,

1968), and subsidence (Maikopian subsidence) of a broad area including Black Sea, south Caspian Sea,

Fore-Caucasus basin and Great Caucasus trough (Scherba, 1993; Popov el al., 1993). The central

segment of the Great Caucasus orogen began to grow from this time (NESMEYANOV. 1992). It means

that a zone of underthrusting in the area of recent southern slope of Great Caucasus orogen was formed

also probably at the same time due to a blockage of the subduction to the south by collision. Thrusts

formed at earliest Oligocene were observed in the field by SHARAFUTDINOV (1991) in the Dagestan (see

Fig. 1 for location) to the north of Great Caucasus, but they were not active during the remaining of

Maikopian.

Great Caucasus

Trans-Caucasus trOU °* 1

Oceanic crust terrane

E.-European

continent

area of rapid subsidence

F G ' 8 ' Sche'iuinc illustraiion of geodynamical evolution of eastern part of Caucasus and adjacent areas (modified after

ERSHOVer ol 1916). Three main stages are shown: 1, pre-collisional Eocene configuration; 2. Maikopian stage, soft

colhsion in the Trans-Caucasus area, rapid subsidence of a broad region; 3. orogenic stage. Great Caucasus orogeny

moiasse basins formation. ° 6

FlG - de r ^° lutio " geodynamique du Caucase oriented el des regions adjacenles (modifie d’apres

ERSHOv a a\. 1996) Trots stades pnncipaux sont presentes : 1. configuration ante-collision Eocene : 2. stade

Matkopten, collision faible dans la region de Trans-Caucasie, subsidence rapide d une large region : 3, stade

orogemque, orogenese du Grand Caucase, formation des bassins molassiques.

The Maikopian subsidence is too long in wavelength to be explained by a flexural response to

orogenic loading. This broad platform subsidence can be driven by loading from a deep source, probably

by flow in the mantle induced by subduction. The proposition of the subsidence of continental

lithosphere above a subduction zone has been made and modelled by MITROVICA et al. (1989) and

GURNIS (1992. 1993). In their model, oceanic lithosphere subducting under a continent acts as a load

inducing the subsidence of a large area in the continent above (scale of 500-1000 km, width increasing

with the shallowing of the slab dip). The model has been used to explain a broad subsidence shown by

deep palaeowater depth in the Late Tertiary development of the Taranaki basin. New Zealand (HOLT &

Si ern, 1994), which, as in the Caucasus, precedes the evolution of a more restricted flexural foreland

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

125

basin. In this model, the subsidence is associated with the beginning of subduction; termination of

subduction leads to an uplift of the area. In our case, the subsidence is contemporaneous with

termination of subduction and new zone of underthrusting only began to form when deep water basin

already existed in the broad area. We suggest that Maikopian subsidence was induced by a rotation

down of the slab after the termination of “southern” subduction. This led to a dragging “of mantle wedge

above the slab downward, resulting in a depression at the surface” as it was discussed by HSUI et al.

(1990J. This process is suggested to induce 1 km excess subsidence in back-arc basins and we have

similar amplitude of Maikopian subsidence taking into account loading of sediments. On the other hand

this process is transient in nature. Influence of the rotating down slab will be decreasing with time and

after some period such “dynamically supported” subsidence has to be changed into uplift. This post-

Maikopian uplift can be attributed as a cause of excess uplift of the bulge on the north of the basin,

which has led to more than I km of erosion. But on most of the territory of the basin the effect of this

uplift is masked by subsidence of the next stage induced by the processes of the next stage of collisional

history.

A collision between the Arabia and the “ Europe ” took place in the middle Miocene-Quaternary

(SENGOR & YlLMAZ, 1981) further to the south in the Zagros area. This continent-continent collision

has led to orogeny in the Caucasus-Crimea region and molasse basins formation. Since 3.4 Ma, a drastic

change in the vertical movements regime occurred in the general area. The Peri-Caspian basin

underwent uplifting in the Miocene which was dramatically changed by rapid subsidence up to 600

meters during ihe last 3.4 Ma (ZHIDOVINOV et al., 1995). The eastern Black Sea basin had a decrease of

the subsidence rate 17-3.4 Ma ago changed by rapid subsidence till the recent time (ROBINSON et al.,

1996). In the south Caspian Sea, the onset of rapid sedimentation and tectonic subsidence began during

early Pliocene at around 5 Ma and the tectonic subsidence reached a very high rate during the mid-

Pliocene (BRUNET et al.. 1997).

As it is clearly seen on the 2D restorations (Fig. 7), the Maikopian basin (34-15.8) differs from

Chokrakian-Quaternary basin (15.8-0 Ma). The shape of Maikopian basin is flattened with slight

dipping to the south, the characteristic wavelength is larger than the size of the section. On the other side

the geometry of the molasse basin (Chokrakian-Quaternary) has a characteristic asymmetrical shape

with flexural deepening to the orogen. This shape is typical for flexural foreland basins formed due to

elastic flexure of lithosphere in response to orogen loading. Such basins were recognized broadly across

Alpine-Himalayan orogenic belt (e.g. KARNER & Watts, 1983;Lyon-Caen & Molnar. 1983;

BRUNET, 1986; LILLIES’/ al., 1994) and for the Caucasus such model was supposed by RUPPEL &

MCNUTT (1990).

Some alternative models of Caucasus foredeep have been presented in the literature. ARTYUSHKOV

(1993) suggested a basalt-eclogite phase transition in the lower crust as a cause of the Caucasus foredeep

origination. He emphasized the deficiency of the Great Caucasus topographical loading and the

diachronism in the appearance of topographic elevation of orogen (since middle Sarmatian) and molasse

basin subsidence (since Maikopian). Indeed, insufficiency of topographic loading itself was recognized

by many researchers for different orogens (e.g. KARNER & WATTS, 1983) and additional loading factors

were proposed as subsurface loading or bending momentum of the slab (Karner & Watts. 1983,

BRUNET, 1986; Sheffels & McNutt, 1986). Phase transitions may be a part of subsurface loading,

new in ARTYUSHKOV's model is the fact that phase transition acts as subsurface loading also in the

basin area. The physical properties of basalt-eclogite phase transition is poorly studied and existing

information shows that in dry conditions the P-T conditions in the lower crust are insufficient for it; the

arguments about input of the fluids are only speculative and do not allow quantitative test at this time.

The contradiction of diachronism between topographic elevation and basin subsidence disappears it we

discriminate Maikopian subsidence and later foreland-type subsidence as induced by different causes.

Other model of Fore-Caucasus foredeep basin was proposed by MIKHAILOV et al. (1997). The

origination and the evolution of the foredeep is connected with small scale viscous convection in the

crust and upper mantle. This model was proposed recently but not fully published and now we have not

enough informations to discuss it.

We will not model the Maikopian subsidence as its characteristic length is larger than the

investigated region and we need to include data on a larger area which is not subject of the present

paper. In this paper, we will model in the flexural mode, only the second part of the basin evolution with

the formation of molasse basin near the orogen. We use the dynamic model of the Fore-Caucasus basin

126

ANDREI V. ERSHOV ET AL.

evolution during the last 16 Ma based on the proposition that the main control is elastic response of

basin lithosphere to the loading in the area of Great Caucasus orogcn.

FLEXURAL MODEL OF LATE MIOCENE-QUATERNARY STAGE

Model of foreland basin origination due to flexural response of lithosphere to loading was proposed

by Jordan (1981) and Beaumont (1981) and was widely used in the 80'th (e.g. Karner & Watts,

1983: Royden&KARNER, 1984; Lyon-Caen & MOLNAR, 1983, 1985, 1989; Lyon-Caen etal., 1985;

Brunet. 1986; Sheffels & McNutt, 1986). Ruppel & McNutt (1990) made such modelling for the

Caucasus orogen. These works were based mainly on the gravity and topography data and often these

constraints were insufficient (e.g. LYON-CAEN & MOLNAR, 1989). In our case, we have an additional

constraint coming from 2D restoration of burial history. It is the shape of the basin and as we know its

evolution in time we can apply flexural model through time. The deep structure of the Caucasus orogen

is complex and poorly known and, in turn, structure of basin lithosphere is more simple and relatively

well known. Our approach allowing to avoid the indefinities related to complexity of orogen deep

structure is to divide the whole system of orogen and adjacent sedimentary basins into two parts: a basin

and a orogen - and to consider the interplay between these parts (Fig. 9) (ERSHOV, 1997). The geometry

of flexural basin depends mainly on three factors: loading of orogen, intraplate stress and elastic-

properties of lithosphere. The knowledge of the basin geometry allows us to estimate the orogen loading

force. Knowledge of the basin shape through time (reconstituted from the 2D kinematical restoration.

Fig. 7) allows us to obtain loading history through time.

The model is based on the numerical solution of standard equation of elastic flexure:

(D w” )”+( P w’ )'+p ast gw=q sed

where D(x) - flexural rigidity, P - intraplate stress, w(x) - vertical deflection of lithosphere, q sed =

p(z) g dz — loading of sediments and water, p as ,gw - buoyancy force. The effective elastic thickness is

expressed through the flexural rigidity:

D=E T e 3 /12(1-V 2 ),

where E - Young modulus, v- Poisson coefficient.

The difference from the standard model is the considered area (basins area only) (Fig. 9) and,

correspondingly, the boundary conditions. The boundary conditions on the right corner were a deflection

w(x/), derived from backstripped section, and zero bending moment (D(xi)w"(xj)=0). The boundary

conditions on the left corner were a deflection w(xq) and a bending momentum D(x 0 ) w"(x 0 ), which both

were varied to obtain the best fit with observed shape of the basin. By changing intraplate stress, flexural

rigidity (EET), left corner deflection and bending momentum values, we have matched the shape of the

basin for each time slice.

Fig. 9.— Configuration and boundary condition of the flexural

model. Only basin lithosphere is considered in flexural

modelling. Observed deflection (w) and zero bending

moment are used as right-corner boundary conditions;

loading force and bending moment as left-comer

boundary conditions. The values of EET (T e ), intraplate

stress P. left-corner bending moment M and loading

force Vq were varied to fit observed geometry of the

basin at each time span.

Fig. 9.— Configuration el conditions aux limiles du modele

flexural. La lithosphere du bassin est settle consideree

dans le modele en flexion. La deflexion observee (w) el

le moment flechissant mil sont utilises comme conditions

aux limites a droite du modele tandis que la force de

surcharge et le moment flechissant sont utilises comme

conditions aux limites a gauche du modele. Les valeurs

de I’epaisseur elastique equivalente EET (T e ), de la

contrainte intraplaque P, du moment flechissant a

gauche M et de la force de surcharge Vq ont ete variees

pour ajuster la geometrie du bassin observee a chaque

etape.

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

127

Fig. 10.— Set of diagrams, illustrating the agreement between backstripped section and profile obtained from the flexural

modelling. The dashed line represents the top of Maikopian from the flexural modelling, the solid line - the top of

Maikopian from the backstripped section (Fig. 7). The time slices are the same as on the picture 7 from the late

Sarmatian.

Fig. 10 .— Ensemble de diagrammes illustrant le bon accord entre les coupes resultant du “ backs! ripping " el celles obtenues

par le modele flexural. La ligne en pointiUes correspond au toil du Maikopien deduit du module flexural, la ligne

continue correspond au toit du Maikopien sur la section apres “backstripping " (Fig. 7). Les tranches de temps sont les

memes que sur la figure 7 a partir du Sarmatien superieur.

As a result, we have time slices of modelled best-1 itted flexural shapes ot the basin. We have chosen

as reference boundary top of Maikopian which is bottom of the foreland-stage basin. The results ot the

flexural modelling for selected time slices are presented on figure 10. The solid line represents the

reference boundary (top of Maikopian) from kinematical restoration of the profile (Fig. 7). The dashed

line represents the modelled position of this boundary from flexural dynamic modelling. The results

show the good agreement between backstripped and flexurally modelled basin geometry.

128

ANDREI V. ERSHOV ETAL.

The fitted level of intraplate stress is far from critical value and its influence on basin shape has a

second order effect. The variation of EET value with time used to obtain the best fit was not large and

all the values were near 60 km. These results are in general agreement with those of RUPPEL & McNutt

( 1990) for the central and eastern parts of Caucasus, where they have found a 40 km thick elastic plate.

To go further in the modelling of this area, we need now to take into account the rheological structure

of the fithosphere and the gravity anomalies for a model of a section crossing the Caucasus and using the

constraints, even poorly known of the southern basin. Other sections in the central and western part of

the Caucasus will be modelled to compare the difference of behaviour of the basins and lithosphere

along the Caucasus orogen. through a different history of the basins evolution.

CONCLUSION

The collisional history of Caucasus area started at the Eocene/Oligocene boundary when north¬

dipping subduction was changed by collision in the Transcaucasus area with Tauride-Anatolide terranes.

It led to the uplifting of the Transcaucasus region, compressional tectonics in the northern areas and

subsidence of broad area including the Fore-Caucasus and Caucasus, the Black Sea and the south

Caspian Sea. On the basis of restored burial history we can separate two main stages of syncollision

molasse basin formation: (1) 34-15.8 Ma ago (Maikopian stage) - early collision, with rapid subsidence

of a broad area; (2) 15.8-0 Ma ago - collisional climax, contemporaneous with a rapid subsidence of

molasse basins, upthrusting of the Great Caucasus to the south, and a local retrothrusting to the north.

The Maikopian subsidence has a too large wavelength to be explained by the elastic flexure of

lithosphere. The cause for Maikopian subsidence of a broad area could be related with the change in

subduction system, when slab rotated down after the termination of subduction in the Transcaucasus

area and induced large scale flow in the mantle causing the subsidence of the continental crust above.

Such subsidence is “dynamically supported" and after some time subsidence has to be changed into

uplift.

The mean palaeowater depths during the early Maikopian estimated on the basis of shape of

clinoforms were near 500-800 m in the middle part and up to 1200 m in the southern part of the basin.

These estimated values are in general agreement with palaeontological data.

Two-dimensional flexural modelling of eastern Fore-Caucasus molasse basin demonstrates that the

observed subsidence of this area during late Miocene - Quaternary time can be explained by the effect of

loading of Great Caucasus orogen. The EET lies near 60 km on the basis of flexural modelling.

On the northern edge of the basin the peripheral bulge uplifted at least during last 5 Ma and probably

since Sarmatian. The time of beginning of uplift is difficult to establish as northern part of the section is

eroded now. The amplitude of erosion is more than 1 km in the northernmost part of investigated area.

The cause of it may lie in a broad uplift inherited from Maikopian subsidence. An asymmetrical

foreland-type subsidence due to the loading of orogen surpassed the effect of post-Maikopian uplift in

the areas adjacent to Great Caucasus orogen.

ACKNOWLEDGMENTS

This work was funded by Peri-Tethys Program (funds n° 95/66. 95-96/66. 95/44 and 95-96/44). The

international programmes Europrobe, INTAS. IGCP-369, and Lithosphere supported our

communications and discussions. We thank A. S. ALEKSEEV, S. CLOETINGH, J. DERCOURT, V. E.

KHAIN, N. V. KORONOVSKY, E. E. MlLANOVSKY. B. P. NAZAREV1CH. D. I. PANOV, Yu

Podladchikov. P. ZlEGLER for fruitful! discussions. J. Granath. R. Stephenson and an anonymous

reviewer for their constructive remarks on a first version of the paper.

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

129

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ZHIDOVINOV N A., ffiDKOViCH. Z.N. & Kovalenko. N.D.. 1995— New data on the stratigraphy of the Upper Pliocene and

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Source: MNHN. Paris

Stratigraphic analysis of the Upper Jurassic

(Oxfordian-Kimmeridgian) Antalo limestone in the

Mekele outlier (Tigrai, Northern Ethiopia):

preliminary data

Luca Martire, Pierangelo Clari & Giulio Pavia

Dipartimento di Scienze della Terra, via Accademia delle Scienze 5, 10123 Torino, Italy

ABSTRACT

The Antalo limestone is an Upper Jurassic formation mainly consisting of interbedded limestones and marls, and is

comprised between two arenaceous, continental formations, the Adigrat sandstone and the Amba Aradam formation. The

Antalo limestone has been studied in its type-area, the Mekele outlier. Two stratigraphic sections have been measured and

correlated. Four units have been distinguished in the Antalo limestone on the basis of gross lithological features. From bottom

to top: a) calcareous-marly unit A (170 m). Massive stromatoporoid- and coral-rich limestones at the base, and cross-bedded

oolitic grainstones, in the upper half, are interbedded with a poorly exposed succession of marls; b) arenaceous unit B (115 m).

Herringbone cross-bedded coarse-grained brown sandstones grade upwards into prevailing marls with thin-bedded sandstones

with parallel and low-angle oblique laminae; c) calcareous unit C (180 m). After a poorly exposed marly unit, a thick

succession of micritic grey to light brown limestones follows with subordinate marly interlayers. The only ammonites to date

found in the Antalo limestone of the Mekele outlier come from these layers; and d) marly calcareous unit D (280 m). It consists

of alternating marls and limestones. Noteworthy is the presence of oolitic grainstones and of stromatoporoid floatstones in the

lower part of the member, and of whitish micritic limestones in the upper part. At the top, the Antalo limestone formation

grades into the overlying marls of the Agula Shales. Stromatoporoids and benthic foraminifer assemblages show that units A

and B are referable to the Oxfordian whereas the units C and D to the Kimmeridgian. Ammonites found in unit C confirm this

picture. Although the geometry of sedimentary bodies is tabular, some slight lateral changes in thickness and facies have been

recognized. The overall depositional setting was probably represented by a low-gradient ramp basically controlled by storm

processes and gently dipping to the East.

RESUME

Analyse stratigraphique du calcaire Antalo dans la region de Mekele (Tigrai. nord de I'Ethiopie) (Jurassique

superieur, Oxfordien - Kimmeridgien): donnees preliminaires.

Le calcaire Antalo est une formation du Jurassique superieur, compose essentiellement d'alternance de calcaires et de

marnes et est encadre de deux formations arenacees continentales, les gres d'Adigrat et la formation de Amba Aradam. Le

calcaire Antalo a ete etudie dans sa region type, dans les environs de Mekele. Deux coupes stratigraphiques ont ete levees et

Martire. L.. Clari, P., & Pavia, G.. 1998. —Stratigraphic analysis of the Upper Jurassic (Oxfordian-Kimmeridgian)

Antalo limestone in the Mekele outlier (Tigrai. Northern E'ihiopia): preliminary data. In: S. Crasquin-Sjleau & E Barrier

( eds), Peri-Tethys Memoir 4. epicratonic basins of Peri-Tethyan platforms, Mem. Mus. natn. Hist, nat., 179 : 131-144. Paris

ISBN : 2-85653-518-4.

Source. MNHN, Paris

132

LUCA MARTIRE ETAL.

correlees. Quatre unites ont ete distinguees dans le calcaire Antaio sur la base de caracteres lilhologiques generaux. De la base

au sommet: a) une unite calcaro-marneuse A (170 m) ; calcaires massifs riches en stromatoporides et coraux a la base et des

c a lea ires oolithiques a stratifications entrecroisees dans la partie superieure, intercales avec des marnes affleurant mal • b) une

unite arenacee B (115 m) ; gres brans grossiers a stratifications entrecroisees en chevrons passant graduellement vers le haut a

des marnes dom.nantes avec des gres en petits bancs avec des lamines parallels ou faiblement obliques ; c) une unite calcaire

, v 80 m >- A P res une unite marneuse affleurant mal, on rencontre une epaisse succession de calcaires micritique gris h marron

clair avec des interlits marneux Les seules ammonites trouvees dans le calcaire Antaio de la bordurc Mekele proviennent de ces

ntveaux ; d) une unite de calcaires marneux D (280 m). Elle es, formee d'une alternance de marnes et de calcaires A noter la

mrrfe , snnAi!M a rl nS A l 1 0ol,th '? ue f s et de . ,1oatsIon f s a stromatoporides dans la partie basale et de calcaires blanchatres dans la

partie superieure. Au sommet la formation du calcaire Antaio passe graduellement aux marnes de la formation Agula Les

Sr b r a ffn d ! St [? mat0p °; ,d6s e ,‘ de f° raminif ^es montrent que les unites A et B peuvent etre rattachees a I'Oxfordien et les

C . el D f u Kln,me ndgien. Les ammonites tfecouvertes dans funite C confirment ce schema. Bien que la geometric des

| quelques changements lateraux d'epaisseur et de facies ont ete reconnus. Le milieu

p,r Ul " r,mpe gr “ dicn ' “ ble - fo " dame " tata **

INTRODUCTION

The Antaio limestone consists of a package of shallow marine limestone-marl alternations about 700

th ' C i k r w e l ab , le 10 ! he Lale Jurassic - The type-area of the Antaio limestone, defined by Blanford

l«/0) is the Mekele outlier, in northeastern Ethiopia, where it crops out over an area of about 7000 km 2

(rig. I). Heie, this succession of marine sedimentary rocks is comprised between continental

terrigenous sediments The older ones are represented by the Adigrat sandstone in turn unconformably

overlying the Upper Paleozoic Karroo complex. The boundary between the Adigrat sandstone and the

Antaio limestone is considered conformable and transitional. The upper continental formation (Amba

Aradam formation) consists of conglomerates and sandstones. An erosional angular unconformity

8l ;Pf rates th f. Antal ° limestone from the Amba Aradam formation which, in the westernmost parts of the

Mekele outlier directly rests upon the Adigrat sandstone. Because of the extreme scarcity of fossils,

direct dating of both Adigrat and Amba Aradam formations has never been possible. The Adigrat

CO £ Sldered 0 P erm °-Triassic age, after paleobotanical studies (Beauchamp &

LEMOIGNE, 1974), or Tnassic -Bathoman on the basis of the supposed transitional boundary to the

Lallovian-Kimmendgian Antaio limestone (MERLA & MlNUCCi, 1938; MERLA etal., 1979). The Amba

Aradam instead, is totally devoid of fossils. It can therefore only be dated in a very general way, bein°

bracketed between the Upper Jurassic Agula Shales and the Eocene volcanics. It is however generally

referred to the (Early) Cretaceous. 6 y

Many references to the Antaio limestone from different parts of the Horn of Africa may be found in

hterature (e.g. Merla & MlNUCCi, 1938; Dainelli, 1943: ARKIN et al., 1971 • Bf.YTH

'wVSArir^; “r el Ql X 19 , 7 ?' TURI et al - 1980: Russo et al - 1994; BOSELLINI et al.',

nniiir le f ,u " 8 f' T . h ® most detailed description of the stratigraphic succession of the Mekele

outlier is due to the work of Blyth (1972) who compiled the explanatory notes of the Mekele sheet

within L a m e ,| Ge . gl ^ ^7 Eth '° pia i ARKIN et al -' 197l) - Five members were distinguished

ml rVL limestone and four broad fames identified on the basis of sediment composition,

nrnoL 6 d the . s P a t ial arrangement of these facies, according to the author, points to a

AmM r Ve ea . stward dee P en,n § from nearshore to deeper marine basin. Moreover, the upper part of the

Antaio limestone, mainly represented by marls and scarcely exposed, was separated in a new

because of!he nrn Un,t T AgU ‘f ShalC (BE 7 TH ’ 1972) ‘ 11 was stl " cons 'dered of Jurassic age and.

because of the presence of gypsum lenses, attributed to a marginal marine environment.

Fossils with precise biostratigraphic resolution, such as ammonites, are generally lacking in the

bS °o& n rth f lhe Mekele outlier and therefore its age is not well constrained. However, on the

rnvfJJr ? h 7 USC and brachl0 P° d associations, it has been referred to the Late Jurassic

(Oxfordian - Kimmendgian: Merla & Minucci, 1938; Dainelli, 1943; Merla etal.. 1979).

strabpTflnhv hLT Pt ° f TL Si °S ° f the Antal ° limestone in lhe Mekele outlier in terms of sequence

Lt o fiLLo h m f by * OS f LU ™ er “ L (I"5). Four units have been distinguished on the basis

mem her Thee 8 basal u m u ember; subtidal member; stromatoporoid-oolitic member; marly

fn a ‘ T Un ‘ tS ' loget , her Wlth the over| y> n g Agula shale, are interpreted as a single 2nd order

transgressive-regressive cycle named Mekele Sequence (BOSELLINI et al, 1995).

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

133

Berahale -•

UKROi

HAG I RF.

SELAM

MEKELE

KHARTOUM

ANTALO

50 kjn

ADDIS ABABA

Fig. 1.— Geographic map of the Mekele outlier and location of the two measured stratigraphic sections (white stars).

Fig. I .— Carte geograpliic/ue de la region de Mekele et localisation des deux coupes levees (etoiles blanches).

Marine, mainly carbonate, deposits of comparable facies and stratigraphic position, still defined

Antalo limestone, are known from other regions of eastern Africa: Blue Nile Basin: RUSSO et al. (1994);

east central Ethiopia: FlCCARELLl et al. (1975), Turi et al. (1980): Danakil Alps: Sagri et al. (1998). In

all these cases, however, the base of the formation seems to be older, Callovian or even Bathonian on

the basis mainly of benthic foraminifera associations (e.g. Pfenderina gr. trochoidea) or ammonites

(Peltaceras sp.) and nannofossils (SAGRI et al., 1998).

Detailed studies are still needed for defining variations in lithology, facies and paleobiological

communities, identifying discontinuities and cyclic patterns, and eventually tracing depositional

sequences across the Mekele outlier. In this paper, the results of a first field trip will be presented. Two

stratigraphic sections have been measured and sampled both for sedimentologic and biostratigraphic

purposes. In spite of the preliminary character of the analysis, some new and interesting data have been

obtained regarding both the age and the sedimentary evolution of the Antalo limestone in the Mekele

outlier.

REGIONAL GEOLOGIC FRAMEWORK

The Mesozoic stratigraphic succession present in the Mekele outlier reflects the tectonic evolution of

the Horn of Africa which is essentially the result of the breakup of the Gondwana supercontinent with

opening of the Indian Ocean as recently summarized by BOSELLINI (1992). This crustal extension was

preceded, in Late Paleozoic times, by a rifting phase that gave rise to a series of faulted basins mainly

134

LUCA MARTIRE ETAL.

oriented NE-SW. These basins were basically filled with continental sediments of the well known

Karroo complex and are best represented in Somalia, Madagascar and India. This rift system was

inundated by the sea, likely coming from the paleo-Tethyan margin sited to the North East (Oman,

Pakistan, North India), at the beginning of the Jurassic (Pliensbachian or even before: Hamanlei

sequence of BOSELLINI. 1992). On the contrary, to the the North e.g. in North Somalia, Ethiopia and

Arabia, the deeply incised Karroo topography was replaced by a Hat landscape of alluvial plains. Here

the first marine deposits are therefore represented by the much younger Callovian, or even Oxfordian, to

Kimmeridgian Antalo limestone (Uarandab sequence of BOSELLINI, 1992). The Late Jurassic

transgression is obviously due to sea-floor spreading between Africa and the Madagascar-India-

Seychelles block that began in Callovian-early Oxfordian time. This marine episode, however, was

short-lived because an Early Cretaceous tectonic event, interpreted as a distal intraplate effect of the

South Atlantic opening, caused an upwarping of the whole Horn of Africa. This resulted in emersion of

most of the Ethiopian and northern Somalia territory and in the deposition of alluvial conglomerates and

sandstones of the Amba Aradam formation.

THE ANTALO LIMESTONE IN THE MEKELE OUTLIER

The study has been carried out in the north-western part of the Mekele outlier geographically

comprised between Mekele, Hagere Selam and Wukro (Fig. 1). Several localities have been visited

during a first campaign (january 1996) and two stratigraphic successions have been measured and

sampled: one is in the western sector, close to the small village of Agbe, between Hagere Selam and Abi

Adi. where only the lower part of the formation is present because of a deeply^incising erosional

unconformity which is directly overlain by the continental sediments of the Amba Aradam formation

(Cretaceous) (Fig. 2). The other section was measured few kilometres north of Mekele along the road to

Wukro. where the middle and upper parts are present (Fig. 2). This section was already described by

BOSELLINI ei al. (1995). It has been measured and sampled in greater detail with both petrographic-

sedimentologic and biostratigraphic purposes. The physical correlation between the Agbe and Mekele

sections is possible because of the presence of an arenaceous unit overlain by micritic limestones and

marls where the only ammonite moulds hitherto found have been collected. This correlation has been

confirmed by microfacies analysis, foraminifers and ammonite biostratigraphy (Fig. 2).

A collection of about 100 rock samples from limestones and sandstones for petrographic analysis of

thin sections and peels, and of 50 samples from marls for micropaleontological purposes (calcareous

nannotossil analysis) has been made.

Lithostratigraphy

The Antalo limestone may be subdivided in four main lithostratigraphic units to be provisionally

considered as informal members. This subdivision has no sedimentological/ paleoenvironmental

connotation or even less sequence stratigraphic meaning: it is just based on gross lithologic differences

and on morphology of weathering profiles with the main aim of enabling identification of “the lithosomes

tor mapping purposes. Furthermore, each unit is not homogeneous internally but consists of a succession

of several packages of beds with even marked lithologic and facies differences from one another. In the

following description all these lithostratigraphic units will be treated with some detail in order to give a

clear, albeit synthetic, picture of the Antalo limestone stratigraphy and to pose the basis for an

interpretation of the sedimentary evolution of the basin.

From bottom to top the succession of the four units is (Fig. 2):

~ Calcareous-marly unit A (about 170 m). The boundary with the underlying sandstones of the

Adigrat formation is rather sharp: the colour changes from white or red to yellow ochre, burrows and

marine fossils appear (bivalves and brachiopods), and the carbonate component of the rock, mainly

represented by bioclasts, becomes abruptly important. Quartz grains, however, are very abundant at the

base and remain still common in the first metres of the Antalo limestone. This unit is here described for

the first time because it is not exposed in the Mekele section studied by BOSELLINI et al. (1995). The

calcareous-marly unit may be further subdivided into three subunits:

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

135

Cross-bedded

sandstones

- T—

Marls

EziL-i

Limestones

1 |

inierDeaaeo

marls and

.•..Ac. ""

- ■ -Ji-|

limestones

Inlerbedded

marls and

sandstones

Conglomerates,

sandstones

and clays

Stromatoporoids

Ammonites

Covered

interval

££) Corals

Ooids

Poorly

exposed

interval

i iy r

i t , u i:

Mekele

Section

Fig. 2.— Simplified stratigraphic columns of the Mekele and Agbe sections.

Fig. 2 — Colonnes stratigraphiques simplifies des coupes de Mekele el Agbe.

Source: MNHN, Paris

OXFORDIAN KIMMERIDGIAN _ KIMM.?

ANTALO LST. Aguia Sh.

136

LUCA MARTI RE ETAL.

A1 (55 m) - Stromatoporoid- and coral-rich floatstones to rudstones are interbedded with grainstones

to wackestones. Stromatoporoids and corals are found mainly in life position (Fig. 3). The grainstones

are usually well sorted and contain skeletal grains (benthic foraminifers, debris of crinoids, ostreid

bivalves) which are commonly coated by thin oolitic cortices or show a micritized rim; intraclasts and

small oncoids are also present. In the wackestones, instead, the grains are represented by sponge spicules

and rhaxes, gastropods and small fragments of stromatoporoids. In the middle part of this subunit a

clearly recognizable interval, 4-5 metres thick, consists of limestones with lisjht grey to yellow chert

nodules. In thin section they appear to consist of packstones with abundant reniform sponge rhaxes. This

subunit is characterized by the presence of several discontinuities: omission surfaces (sensu BROMLEY

1975, 1996) identified by firm ground burrows and the reddening of the surface; a hard around

underlined by borings, encrustation by oysters, serpulids and iron oxides, which marks the top of the

subunit A1 (Fig. 4). K

Fig. 3.— Antalo limestone, subunit Al: globose stromaloporoids encrusted by corals. Agbe section.

hiG. 3 — Calcaire Antalo, sous-unite Al: stromatoporides globuleux incrustes par des coraux. Coupe de Agbe.

A- (55 m) - This subunit is mainly made up of poorly exposed yellowish marl-limestone alternations.

Brachiopods and pholadomiid bivalves, in life position, are common in the marls. Limestone beds, from

10 to 80 cm thick, consist ot a variety of lithologies, from bioclastic rudstones or grainstones with

stromatoporoid and echinoderm fragments, to oolitic grainstones and subordinated bioclastic

wackestones. Some limestone layers show basal erosional features (burrow casts) and/or parallel to low

angle laminae. Hard grounds, highlighted by bivalve borings and oyster encrustations, are occasionally

present at the top of wackestone beds.

A3 (18 m) - Cross-bedded oolitic grainstones with locally abundant siliciclastic sand fraction. Many

quarlz grains make up the nuclei of ooids. Bivalve-rich, coquinoid beds are common especially in the

lower part. Rare bnnodality in the dip of oblique laminae suggest a possible tidal influence. Thin beds of

dasyclad-rich wackestones are also present (Fig. 5). In the upper 8 metres, overlying a burrowed and

reddened horizon (hard ground), the facies changes again to alternations of medium beds of bioclastic-

ooidal grainstones still showing low angle laminae with mottled locally nodular bioclastic marls A

EVOLUTION OF THE EASTERN FORE-CAUCASUS BASIN

137

covered 40 m-thick interval, likely consisting of fine grained marly sediments, separates the A3 subunit

from the overlying arenaceous unit.

— Arenaceous unit B. In the Agbe sector only 14 metres of cross-bedded, often burrowed, tobacco

sandstones crop out; they are interbedded with coquinoid packstones rich in ostreid valves. Higher up

the section continues with about 50 metres of limestone-marl alternations in which scattered sandstone

layers still occur. The arenaceous unit is instead best developed in the Mekele section (Fig. 6). Here two

subunits are recognizable.

Fig. 4.— Antalo limestone, subunit A1: hard ground bored and encrusted by Fe oxides and ostreids at the top of the subunit.

Agbe section.

Fig. 4 .— Calcaire Antalo, sous-unite A1 : surface dttrcie creusee et encroutee par des oxydes defer et ostreides au sommet de

la sous-unite. Coupe de Agbe.

B1 (65 m) - Upward thickening and coarsening cycles evolving from marly siltstones or sandstones

to cross-bedded coarse-grained brown sandstones. Coquinoid sandy limestones are frequent. A tidal

influence on deposition of coarse sandstones is documented by herringbone structures. At the base,

black-coloured, phosphatic ooid grainstones are present.

B2 (49 m) - This portion of succession is mainly represented by marls and therefore is poorly

exposed. Scattered thin to medium layers of fine sandstones with variable amounts of ostreid

disarticulated shells however are recognizable along gentle slopes. These beds are characterized by

parallel or low angle laminae and by erosional bases which show casts of Rhyzocorallium or

Thalassirtoides burrows.

— Calcareous unit C (180 m). The lower part (subunit Cl) is represented by a mainly marly unit

(about 50 m), poorly exposed but clearly distinguishable from the underlying marls because ot the

lighter colour and the absence of sandstone layers (Fig. 6). A thick succession of micritic grey to light

brown limestones follows with subordinate marly interlayers (subunit C2: about 30 m). At the very base,

stromatoporoid and coral fragments together with sponge spicules and rhaxes, benthic foraminifers

( Everticyclammina , Alveosepta ) and oncoids occur. Higher up in the section, Zoophycos are common.

138

LUCA MARTIRE ETAL.

brachiopods and Pholadomiid bivalves are frequently found in life position. Some ammonite moulds

have also been found in these layers. The third subunit C3 (75 metres) is characterized by limestone-

marl alternations. Most limestone beds display typical features of storm layers: grain-supported textures

(peloidal grainstones to coquinoid rudstones), erosional bases with burrow casts (Rhyzocorallium,

Planolires, Tlialassinoides), parallel to low angle laminae (Fig. 7). Both thinning and thickening upward

cycles occur: the former consists of thin to very thin beds, whereas the latter end with medium to thick

beds showing omission surfaces or even reddened and bored hard grounds. The paleontological content

is similar to that of the lower subunit, except for the absence of ammonites and the greater abundance of

benthic foraminifers. At the top of the unit C, marly interlayers disappear and purely micritic limestones

give rise to a cliff 25 metres high (subunit C4. Fig. 6). Mudstones and wackestones are the prevailing

textures: they are organized in thick beds quite regularly bounded by omission surfaces. No meaningful

change in palaeobiologica! assemblages has been recognized.

Fig. 5. Antalo limestone, subunit A3: dasyclad-rich (Trinocladus perplexus?) wackestones interbedded with cross-bedded

grainstones. Agbe section.

Fig. 5. Calcaire Antalo, sous-unite A3 : wackestones riches en dasycladales (Trinocladus perplexus?) intercales avec des

grainstones d stratifications entrecroisees. Coupe de Agbe.

— Marly-calcareous unit D (280 m). On the whole this unit is poorly exposed because marls prevail

over limestones especially in the upper part. Some prominent calcareous intervals however are

recognizable which are potentially precious in facies analysis and lateral lithostratigraphic correlation.

Over about 70 metres of poorly exposed marl-limestone alternations showing an increase of bioclastic

packstones towards the top, the first of these calcareous intervals crops out. It is represented by a 10

metres thick set of beds of cross-bedded oolitic-bioclastic grainstones. Nerineid gastropods over 10 cm

long are abundant and often display iso-orientation. Under the microscope, the presence of a debris of

dasyclad algae is noteworthy. In the top 2 metres, the texture changes to wackestones and packstones;

stromatoporoids, both in fragments and entire in life position, dominate the paleobiological assemblage.

The second calcareous interval is located at 240 metres from the base of unit D. It consists of whitish

micritic limestones about 20 metres thick. Bedding surfaces are plane parallel and beds range from thin

Source: MNHN. Paris

STRATIGRAPHIC ANALYSIS OF THE UPPER JURASSIC ANTALO LIMESTONE (ETHIOPIA)

139

to medium. Both fossils and sedimentary structures are missing (Fig. 8). A hard ground, overlain by a

thin lag of lithoclasts of the same micritic limestones, separates this interval from the following

alternations of marls and bioclastic, current laminated limestones probably corresponding to storm

layers. Worth mentioning are scattered thin beds occurring in the lower part of a 100 metres thick

covered interval directly underlying the micritic limestones. These beds consist of spiculitic cherty

limestones showing parallel and small scale cross laminations.

Fig. 6 .— Antalo limestone: the tract of section from subunits B1 to C4 is observable in the lower part of the Mekele section.

The subunits BI and C4 are particularly well exposed and recognizable in the weathering profile. Note the sharp change

of colour between units B and C (large arrow).

Fig. 6 — Calcaire Antalo : I'ensemble de la coupe pour les unites Bl a C4 est observable dans la partie inferieure de la coupe

de Mekele. Les sous-unites Bl et C4 sont particulierement bien exposees el reconnaissables dans la coupe erodee. A

noter le changement de couleur entre les unites B et C (fleche large).

In the studied area, the uppermost Antalo limestone is very poorly exposed. Therefore, the boundary

with the overlying Agula Shale, defined by Beyth (1972) probably on the basis of photogeological

interpretations, cannot be recognized, as already observed by BOSELLINI et al. (1995).

The diagenetic features of the Antalo limestone have also been investigated and some selected

samples have been studied also by means of cathodoluminescence (CL) observations. Some interesting,

though preliminary, results have been obtained. They concern dissolution features present within ooid-

bearing facies both in the subunit A3 and in the unit D. In the subunit A3 cm-wide, irregularly shaped

dissolution vugs cut through grains and previous cements. In the other case, dissolution affected only

nerineid shells. Cement stratigraphy, revealed by CL analyses, demonstrate that generation and filling of

biomoldic cavities took place after the complete lithification of the surrounding sediment. In both cases

dissolution was likely related to flushing of meteoric waters.

140

LUCA MARTI RE ETAL.

Biostratigraphy

Biostratigraphic data concerning the Antalo

limestone in the Mekele outlier are scattered.

They are based essentially on foraminifers and

stromatoporoids and allow to confirm an overall

Oxfordian-Kimmeridgian age. The first signi¬

ficant micropalaeontological assemblage occurs

about 30 metres over the base of the Antalo

limestone, within the stromatoporoid-rich subunit

Al. It is represented by Kurnubia palastinienis

Henson, Nautiloculina oolithica Mohler and

Pseudocyclammina sp. and points to the

Oxfordian (e.g. Simmons & Al-Thour, 1994)

(Fig. 9a). This assemblage is replaced by a one

dominated by taxa like Alveosepta powersi

(Redmond) and Everticyclammina virguliana

(Koechlin) characteristic of the early

Kimmeridgian (Fig. 9b) (e.g. SIMMONS & AL-

Thour, 1994). This change occurs in the

calcareous unit C about 20 metres above the top

of the arenaceous unit B in the Agbe section. The

data based on foraminifers seem to be confirmed

by preliminary studies of stromatoporoids (A.

RUSSO, pers. comm.). Taxa recognized in the

same subunit Al include Shuqraia zuffardi

(Wells), Dehornella harrarensis (Wells), D.

crustans Hudson and Actinostromarianina praesalesensis Zuffardi Comerci. According to TOLAND

(1994), this assemblage may be referred to the Oxfordian because of the absence of the genus

Burgundia. On the contrary, the stromatoporoid-rich layers occurring in the marly-calcareous unit D, is

characterized by Dehornella harrarensis (Wells), IPromillepora pervinquieri Dehorne, Burgundia

ramosa Pfender, B. trinorchii Dehorne, Actostroma damesini Hudson, Actinostromarianina lecompti

Hudson, which point to a Kimmeridgian age (TOLAND, 1994). Nannofossil assemblages have been also

studied but, owing to the poor preservation state, they do not contribute to the refinement of the

biostratigraphic framework (LOZAR, pers. comm.).

Fig. 7.— Antalo limestone, subunit C3: one of the frequent

shell-rich storm layers. Note the sharp basal boundary.

Mekele section.

Fig. 7.— Calcaire Antalo. sous-unite C3 : un des frequents

niveaux de tempetes riches en coc/uilles. A noter le

contact basal brutal. Coupe de Mekele.

Ammonites have been found in the lower part of the calcareous unit C in both sections. At A»be at

the top of the section, few metres below the boundary with the Amba Aradam formation, ammonites

referable to Ataxtoceras (Parataxioceras) gr. polyplocum (Reinecke) have been collected (Fig. 9c, d). In

the other section (Mekele) the assemblage is richer although only two taxa have been found:

Ptychophylloceras sp. (juv. specimens) and Ataxioceras (A.) gr. discoidale Schneid (Fig. 9e). These

assemblages are not comparable to the ones described by Sagri et al. (1998) in the Danakil Alps which

are dominated by Mayaitids and indicative of the middle Oxfordian. The Mekele ammonites instead

bear more elements of similarity with forms reported by VENZO (1959) from the Harar region and may

be referred to the early Kimmeridgian. J

DISCUSSION

The available data are not sufficient to propose a well-grounded paleoenvironmental and

sedimentologic interpretation of the Antalo limestone in the Mekele outlier. The two measured sections

are about 40 km apart and their stratigraphic overlap is minimum (Fig. 2). Moreover, the percentage of

■ ‘u tervals 1S more than 40% at . A § be and in the lower part of the Mekele section, and exceeds

00 4 in the upper part. Facies analysis, although biased by the just exposed factors, has led to the

recognition of some diagnostic facies or facies associations: cross-bedded oolitic grainstones associated

to minor dasyclad-bearing wackestones, herringbone cross-bedded sandstones with ostreid-rich layers,

stromatoporoid- and coral-bearing rudstones to floatstones, bioclastic or peloidal storm layers with

erosional bases interbedded with marls, thin bedded micritic limestones and marls characterized by

Source : MNHN, Paris

STRATIGRAPHIC ANALYSIS OF THE UPPER JURASSIC ANTALO LIMESTONE (ETHIOPIA)

141

pelagic biota (ammonites, nannofossils). These facies point to an overall carbonate ramp system

episodically affected by a high siliciclastic input as already suggested by previous authors for the Antalo

limestone in the same area (BOSELLINI el al., 1995) or in other regions (SAGRI el al., 1998). The vertical

organization of these facies, ranging from inner ramp oolitic shoals or sandy estuarine systems to outer

ramp or basin muddy sediments deposited below storm wave base level, reveals several relative sea-

level changes. The complex pattern of these changes still bears some points of uncertainty because of

FIG. 8.— Antalo limestone, unit D: detail of the evenly bedded, barren micritic limestones present at the top of the unit. Mekele

section.

Fig. 8 .— Calcaire Antalo, unite D : detail tie calcaires micritiques, regulierement stratifies, azoiques, presents au sommet de

I'unite. Coupe de Mekele.

the presence of enigmatic facies such as the scarcely fossiliferous, homogeneous micritic limestones

(subunit C4 and top of unit D) whose paleoenvironmental interpretation is doubtful. They could be

interpreted either as deposits of a restricted inner ramp or as (hemi)pelagic basinal or outer ramp

deposits. In fact the former interpretation has been applied to similar and coeval facies of the Antalo

limestone by SAGRI et al. (1998). The absence of both biota and sedimentary structures distinctive of a

lagoonal setting together with the presence of calcareous nannofossil remains, revealed by SEM

observations, suggest a more likely basinal origin.

For the same reasons above exposed, a clear picture of lateral facies and thickness variations of

sedimentary bodies cannot be reconstructed as well. However, reconaissance field work in the

northwestern part of the Mekele outlier has evidenced some slight but significant changes. The thickness

of the whole formation increases from west to east and. more in particular, the basal calcareous-marly

unit A shows the following trends from west to east: a) massive coral- and stromatoporoid-bearing beds

decrease in thickness and fossil content, and are separated by increasingly thicker marly layers; b) the

oolitic unit (subunit A3), thick-bedded and characterized by large-scale cross bedding in the Agbe

section, grades into a succession of thin bedded calcarenites with hummocky cross-stratification and

142

LUCA MARTIRE ETAL.

Fig. 9.— a. Km nubia palastiniensis Henson and Nautiloculina sp. Agbe section, subunit Al; b, Alveosepta powersi

(Redmond). Mekele section, subunit C3; c, d. Ataxioceras (A.) gr. discoidale Schneid. Agbe section, unit C. (1.65x); e,

Aiaxioceras (Parataxioceras) gr. polyplocum (Reinecke). Mekele section, subunit C2. (1.4 x).

FIG. 9 —a. Kurnubia palastiniensis Henson el Nautiloculina sp. Coupe de Agbe. sous-unite AI : b. Alveosepta powersi

I Redmond). Coupe de Mekele. sous-unite C3 ; c. d. Ataxiocera.v (A.) gr. discoidale Schneid. Coupe de Agbe. unite C -

xl.65 : e. Ataxioceras (Parataxioceras) gr. polyplocum (Reinecke). Coupe de Mekele. sous-unite C2 - xl.4.

STRATIGRAPHIC ANALYSIS OF THE UPPER JURASSIC ANTALO LIMESTONE (ETHIOPIA)

143

wave ripple lamination in the surroundings of Wukro. In addition to this, the arenaceous unit B, clearly

recognizable in the morphology in the Mekele section, seems to disappear west of Wukro. This picture

is congruent with an eastward trend of thickening and deepening of the Antalo limestone as suggested

by BOSELLINI et al. (1995) and SaGRI et al. (1998) in the Shekat region and Danakil Alps respectively.

A so far underestimated feature of the Antalo limestone is the common presence of discontinuity

surfaces which are widespread in every member except for the arenaceous one. They range from

omission surfaces, evidenced by firm-ground burrows, to hard grounds, documented by borings, Fe-

oxide coatings and/or bioencrustation by ostreids (Fig. 4). These surfaces, which underline hiatuses of

variable extent and correspond to significant changes in the environmental parameters controlling

deposition, may be a great aid in lateral correlations. They should be considered as potential tools for

subdividing the formation in physical stratigraphic units (allostratigraphic units) correlatable across

facies. Moreover, once the more laterally persistent surfaces are recognized, they will enable

chronostratigraphic correlations with deeper parts of the basin more detailed than biostratigraphy can

allow in a formation where ammonites are very scarce, nannofossils poorly preserved and benthic

foraminifers poorly resolutive.

CONCLUSION

The preliminary results of this study may be summarized as follows:

— refinement of the lithostratigraphy of the Antalo limestone, which consists of more than 150

metres of limestones and marls underlying the well recognizable arenaceous member, previously held as

the base of the formation (BOSELLINI et al., 1995);

— recognition that the arenaceous unit is separated from the Adigrat sandstones by about 150 m of

limestones, poses the question of the causes of this terrigenous input of sediments: a climatically driven

increase in continental run-off or a tectonic-related rejuvenation of the inland are the more probable

candidates. Moreover, the sequence stratigraphic interpretation of the Mekele sequence (BOSELLINI et

al., 1995) needs to be revised in the light of these new data;

— confirmation of the Oxfordian - Kimmeridgian age of the Antalo limestone based on benthic

foraminifer and stromatoporoid assemblages. Ammonites, newly found in the middle part of the

formation, allow to refer the lower part of the calcareous unit C to the early Kimmeridgian in accord to

the other biostratigraphic data;

— paleoenvironmental interpretation: stratigraphic and sedimentologic analyses suggest that the

overall depositional setting was represented by a low-gradient ramp basically controlled by storm

processes. Relative sea-level changes are considered to be the main factor in causing the sharp

superposition of outer ramp (micritic limestones, marls with thin tempestites) and inner ramp (oolitic

grainstones, coral-stromatoporoid rudstones) facies;

— recognition of slight lateral changes in thickness and facies in an east-west direction revealing a

possible eastward deepening of the ramp, in accord with palaeogeographic reconstructions proposed by

other authors (BOSELLINI et al., 1995; SAGRI et al., 1998);

— recognition of several discontinuity surfaces, which are potential tools for subdividing the Mekele

sequence (BOSELLINI et al., 1995) in groups of cycles, or parasequences. and for correlation with deeper

parts of the basin to be studied in the future.

ACKNOWLEDGMENTS

We wish to thank Dr. Solomon Tadesse and Dr. Getaneh Assefa (Addis Ababa) for introducing us

into Ethiopian geology and stratigraphy, and for their kind collaboration in organizing the field work. C.

NERI (Ferrara 1 ) and^A. RUSScf (Modena) are gratefully acknowledged for their help in field and

laboratory analyses, and F. ATROPS (Lyon) for useful advices about Kimmeridgian ammonites. Many

144

LUCA MARTIRE ETAL.

thanks to A. Paganl N. Colanero and G. Balbi of the Italian Cooperation for logistic facilities

during our stay at Mekele. Financial support by Peritethys programme, funds n° 94-65, 95-78 and

95/96-78.

REFERENCES

Arkin, Y„ Beyth, M„ Dow, D.B., Levitte, D.. TLmesgen Haile & Tsegaye Hailu, 1971.— Geological map of Mekele,

sheet area ND-37-11, Tigre Province, scale 1:250.000. Ethiopia Geological Survey.

Beauchamps, J. & Lemoigne, Y., 1974.— Presence d'un bassin de subsidence en Ethiopie centrale et essai de reconstruction

P^Jeogeographique de l’Ethiopie durant le Jurassic. Bulletin de la Societe geologique de France, Paris, (7), 16: 563-

Beyth, M.. 1972.— Paleozoic-Mesozoic sedimentary basin of Mekele outlier, northern Ethiopia. The American Association of

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Bos ellini, A.. 1992.— The continental margins of Somalia. Structural evolution and sequence stratigraphy. American of

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Bosellini, A., Russo, A. & Getaneh Assefa, 1995. — 11 Calcare di Antalo nella regione di Makalle (Tigrai, Etiopia

settentrionale). Atti della Accademia Nazionale dei Lincei. Rendiconti Fisiche. serie 9. 6: 253-267.

Bromley, R.G., 1975.—Trace fossils at omission surfaces. In: R.W. Frey (ed.). The Study of Trace Fossils. Springer-Verlag

New York: 399-428 b

Bromley. R.G.. 1996.— Trace fossils: Biology. Taphonomy and Applications. Chapman & Hall, London: 1-361.

Dainelu, G., 1943.— Geologia dell Africa orientate italiana. Reale Accademia d'ltalia, Roma: 4 vol.

Ficcarelli, G., Pirini-Raddrizzani. C. & Turi. A.. 1975.— Analyses of the microfacies of Antalo Limestone in the Dire

Dawa area. Ethiopia. Societa Geologica Italiana, Bollettino, 94: 759-770.

Merla, G. & MiNUCCI, E.. 1938.— Missione geologica nel Tigrai. Reale Accademia d'ltalia, Roma: 1-336.

Merla, A.. Abbatf., E„ Azzaroli. A., Bruni. P.. Canute P.. Fazzuoli. M.. Sagri, M. & Tacconi, P., 1979.— A Geological

Map of Ethiopia and Somalia. CNR, Firenze: 1-95.

Russo, A., Getaneh Assefa & Balamwal Atnafu, 1994.— Sedimentary evolution of the Abbay River (Blue Nile) Basin.

Ethiopia. Neues Jahrbuch fiir Geologie und Palaeontologie. Monatshefte. 5: 291 -308.

Sagri, M.. Abbate. E.. Azzaroli, A., Balestrieri. M.L., Benvenuti, M., Bruni, P., Fazzuoli M Ficcarelli G

Marcucci, M„ Papini. M.. Pavia, G„ Reale. V„ Rook, L. & Tecle. T.M.. 1998.— New data on the Jurassic and

Neogene sedimentation in the Danakil Horst and Northern Afar Depression. Eritrea. In: S. Crasquin-Soleau & E.

Barrier (eds). Peri Tethys Memoir 3: stratigraphy and evolution of Peri-Tethyan platforms. Memo ires du Museum

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Simmons, M.D. & Al-Thour. K.. 1994.— Micropaleontological biozonation of the Amran Series (Jurassic) in the Sana'a

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FUR', a - b |GL L. & Pirini-Raddrizzani. C„ 1980.— Microfacies of the Antalo Limestone (Middle to Upper Jurassic) in some

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Source: MNHN, Paris

Stratigraphic and palaeogeographic survey of the

Lower and Middle Jurassic along a north-south

transect in western Algeria

Serge Elmi Yves ALMERAS M’Hamed Ameur i2 \

Jean-Paul BASSOULLET A Mohamed BOUTAKIOUT ,4 >

Miloud BENHAMOU i21 , Abbes Marok m , Larbi MEKAHLI ,2 \

Abderrahmane MEKKAOUI (S> & Rene MOUTERDE 161

"’UFR des Sciences de la Terre, University Claude Bernard, UMR 55-65 CNRS

27-43, boulevard du 11 Novembre, F-69622 Villeurbanne Cedex, France

<2> Institut des Sciences de la Terre (IGMO), Equipe de Recherche 3101-05-03-92, Universite d'Oran,

B.P. 1524 El M'daouer. DZ-31000 Oran, Algerie

’’’CNRS, UPRES EA 2250 Laboratoire de Geobiologie, Biochronologie et Paiyontologie humaine

Universite de Poitiers, 40, avenue du Recteur Pineau, F-86022 Poitiers, France

l4) Institut des Sciences de la Terre, Faculte des Sciences, Universite Mohamed V

Avenue Ibn Batouta, MA-Rabat, Maroc

<5 ’Etablissement de Recherche et d’Exploitation Minieres, Centre de Bdchar, Algerie

<61 Centre International d’Etudes du Lias, Universite catholique,

25, rue du Plat, F-69288 Lyon Cedex 02, France

ABSTRACT

A general review of the available data on the Lower and Middle Jurassic of western Algeria is briefly summarized here. The

Tlemcen Domain is characterized by: a) late development of the initial carbonate platform (late Sinemurian to early

Pliensbachian); b) a late transgression or a late deepening on the more prominent shoals (late Pliensbachian to early Bathonian);

c) limited geographic expansion of the middle carbonate platform (Aalenian-early Bajocian); d) strong deepening during the

late Bajocian and the early Bathonian leading to the submerging of the major part of the shoals with the exception of some

Elmi, S„ Almiras, Y„ Ameur, M„ Bassoullet, J. P„ Boutakiout, M„ Benhamou, M„ Marok, A., Mekahli, L.,

Mekkaoui, A. & MOUTERDE, R„ 1998. — Stratigraphic and palaeogeographic survey of the Lower and Middle Jurassic along a

north-south transect in western Algeria. In: S. CraSQUIN-Soleau & E. Barrier (eds), Peri-Tethys Memoir 4: epicratomc

basins of Peri-Tethyan platforms, Mem. Mus. natn. Hist, nat., 179 : 145-211. Paris ISBN : 2-85653-518-4.

Source: MNHN, Paris

146

SERGE ELMI ETAL.

seamounts within the Tiaras Mountains; e) influxes of siliciclastic turbidites within the marly sedimentation during the

Callovian and the early Oxfordian. The most important feature of the High Plains is the renewal of the sabkha regime during the

Toarcian. in relation to tectonic reorganisation of the palaeogeographic pattern. The major feature of the Atlas domain (Ksour

Mountains) is. by comparison with the Tlemcen domain, the early development of the initial carbonate platform, probably as

early as the Rhaetian-Hettangian in the most subsiding subbasin (Ain Ouarka, Chemarikh). The lower Hettangian age has been

proved by the first known occurrence of an Hettangian ammonite, in the south of the Rif-Tell (Caloceras sp.). The Sinemurian

is well dated by rich ammonite faunas. The subsiding umbilics became hemipelagic during the Sinemurian with radiolarian

limestones. Regional peak deepenings happenned during the late Pliensbachian. the early Toarcian and the late Bajocian. The

return to a platform environment began diachronously during the late Bajocian and the early Bathonian. The Figuig (eastern

Morocco) Atlas sustained a rapid and strong subsidence and deepening during the late Sinemurian in the Figuig Umbilic.

Sedimentary and structural features suggest the importance of local tectonic control. The transition to the Saharian Craton is

documented in the Southern Grouz (Koudiat el Ha'fddoura) where newly collected brachiopods indicate late Pliensbachian

(Domerian) and late Bajocian relative sea level rises. All these data are coherent with the model of aborted rifts or aulacogens

developed along the Saharian Atlas and along the Tlemcen domain. But the evolution of these two longitudinal furrows has

been diachronous. The present study clearly indicates that regional tectonic events overprint the global signal and that an

eustatic sea-level chart must be the result of comparisons between different plates as tectonically uncoupled as possible. A new

ammonite species (Hammatoceras roubanense n. sp. Elmi) from the middle Toarcian is described.

RESUME

Etude stratigraphique et palcogeographique du Jurassique inferieur et moyen le long d'un transect nord-sud en

Algerie occidentale.

Un expose succint des facies et des donnees biostratigraphiques sur le Jurassique inferieur et moyen de I'Ouest algerien

conduit a une reconstruction palcogeographique et paleodynamique d'une transversale, longue de 700 km. depuis la

Mediterranee et la ChaTne alpine jusqu'au Craton saharien. Le domaine tlemcenien se distingue par': a) installation tardive de la

plate-forme carbonatee initiale (Sinemurien superieur- Pliensbachien inferieur = Carixien) ; b) enfouissement tradif des hauts-

fonds les plus saillants (du Pliensbachien superieur-Domerien au Bathonien inferieur et meme au Callovien inferieur dans la

region des Traras ; c) extension geographique limitee de la plate-forme carbonatee mediane sur les bords de sillons ou

d’ombilics en cours d'approfondissement par suite d'un decouplage tectoniquement control^ (Aalenien-Bajocien inferieur) ; d)

fort approfondissement pendant le Bajocien superieur et le Bathonien inferieur; e) arrivee de turbidites silicoclastiques au cours

du Callovien et de FOxfordien inferieur. La profondeur maximale est atteinte h 1'Oxfordien terminal. Elle est suivie d'une

inversion rapide illustree par la progradation des gres prodeltaiques de FOxfordien supdrieur-Kimmeridgien inferieur. Les

Hautes Plaines sont caracterisees par la reapparition des facies confines, et meme des sebkhas, pendant le Toarcien. II s'agit, la

encore, d'une preuve de l’intensite de la differenciation tectonique au debut de cet etage puisque, dans les regions contigues, un

approfondissement notable se deroule contemporainement, illustre par des phenomenes de resedimentation en masse (turbidites

calcaires). La principale caracteristique des Monts des Ksour (domaine atlasique) consiste dans le developpement precoce de la

plate-forme carbonatee initiale. probablement des le Rhetien et le debut de l'Hettangien dans l’axe des futurs sillons (Ain

Ouarka, Chemarikh). La presence d’une ammonite de l'Hettangien inferieur est etablie. pour la premiere fois dans le Maghreb

au Sud de la Chaine alpine (Rif et Tell). II s'agit probablement d'un Caloceras sp. Les ombilics deviennent hemipelagiques

pendant le Sinemurien avec des calcaires a radiolaires. Apres cette periode de differenciation, des approfondissements

important se developpent pendant le Toarcien inferieur et le Bajocien superieur. Ces phenomenes sont largement controles par

la tectonique locale. Le cycle sedimentaire s’inverse ensuite avec le retour diachrone a un environnement de plate-forme

proximate (de la fin du Bajocien superieur a la fin du Bathonien inferieur). Dans F Atlas de Figuig (Maroc oriental a Fextremite

occidentale des Monts des Ksour), la subsidence et Fapprofondissement deviennent dominants pendant le Sinemurien

superieur. Les controles paleotectoniques provoquent la differenciation de Fombilic de Figuig ou les breches de pente, la

resedimentation de materiaux transports depuis les bordures et les phenomenes de glissement sont spectaculaires. La transition

au Craton saharien intervient brutalement; ainsi il y a passage en quelques kilometres depuis les series de sillon (Grouz

marocain) a celles de la bordure saharienne (Grouz algerien : Koudiat el Haiddoura). Dans ces dernieres, la decouverte de

gisements de brachiopodes permet de reconnaitre les episodes de haut niveau marin du Domerien et du Bajocien superieur. Une

nouvelle espece d'ammonite du Toarcien moyen (Hammatoceras roubanense sp. nov. Elmi) est decrite.

INTRODUCTION

Preliminary remarks

O ur P re yi° us publications have set the framework for precise correlations at the regional scale,

especially along transects situated westward and eastward of the Algeria-Morocco border (BASSOULLET

1966, 1968, 1971; ELMI, 1971a, b; 1978, 1981a, 1983, 1987, 19963*; 1997; MEKAHLI et al., 1994). Many

Source: MNHN. Paris

JURASSIC OF WESTERN ALGERIA

147

data are presented in several unpublished Ph-D and Master thesis (Bassoullet, 1973; Guardia, 1975;

DouiHASNl, 1976; AMEUR, 1978, 1988; BENHAMOU, 1983; Mekahli, 1988, 1995; AiT OUALI, 1991;

MAROK, 1995, 1996; Ouali-MEHADJI, 1995; TLlLl, 1995). A rapid survey has been also made by

ClSZAK (1993) using data available in the litterature. Kazi-TanP S thesis (1986) is also a general review

of second hand data. Some lithostratigraphic synthesis have tried to give a simple chart for a large part

of Western Maghreb (FEDAN, 1989; KAZI-TANI, 1986; AfT-OUALI, 1991) but the units are often

diachronous and/or sedimentologically heterogenous and they suppose that the correlations are better

established than they really are. Only a brief summary of some important results can be given here.

Tables 1 and 2 summarize the chronostratigraphic and biostratigraphic units used for this report. They

will not be discussed here. The general location of the Jurassic outcrops is given on figures 1 and 26.

The present paper has been written under the direction of Serge Elmi. The authors of the different

parts are: Serge ELMI (Introduction; The Rhar Roubane and Tlemcen Mountains; Main

palaeogeographical and palaeostructural events; Palaeontological remarks); Serge ELMI, M‘Ahmed

AMEUR (felviiloud BENHAMOU (The Traras Mountains); Abbes Marok, Serge ELmi & Larbi Mekahli

(Oran High Plains, The Sidi el Abed Mountains); Larbi MEKAHLI, Serge ELMI, Jean-Paul BASSOULLET,

Yves ALMERAS & Rene MOUTERDE (The Ksour Mountains and the Atlas Domain); Serge ELMI &

Mohamed BOUTAKIOUT (Figuig Subbasin or Umbilic); Abderrahmane MEKKAOUI, Serge ELMI, Miloud

BENHAMOU & Larbi MEKAHLI (The transition to the Sahara).

The Jurassic of north west Maghreb can be divided conveniently into three formal lithostratigraphic

“Groups” (AUGIER, 1967; GUARDIA, 1975) which are diachronous as they are related to the tectono-

sedimentary history of the area as well as to more general controls (Tethyan and Atlantic dynamics and

global eustacy). These groups are named here in the north-west corner of Algeria:

— the Lower Carbonate Group or Traras Group (Lower Jurassic to Bathonian);

— the Middle Sandy-Argillaceous Group or Selib Group (Callovian to lower Kimmeridgian);

— the Upper Carbonate Group or Tlemcen Group (Kimmeridgian-Tithonian).

In the Atlas of Morocco and western Algeria, the Upper Carbonate Group is replaced by deltaic

sediments (Ksour Sandstones Group, for instance). Sequential divisions will be used with care because

they are often interpretative and controversial. The present sequential language is too much linked to a

sedimentologic model which does not take into account the actual physiography of the sedimentary

areas.

The charts of the formations (Tables 3 and 4) are relatively detailed in order to reflect the structural

and palaeogeographical complexity of the area and to avoid simplified and erroneous correlations. They

reflect alstTthe diversified pattern of the facies in a region during a period of intensive taphrogenetic

differentiation. Formations will be briefly defined when necessary. The tentative division of the Lower

Jurassic in four formations (LI to L4) by AiT OUALI (1991) is based on sequential hypothesis. Their

chronologic correlations are rarely proved. They are roughly comparable to the "tectono-stratigraphical

episodes” of ELMI (1996b).

Lists of fossils will be given only if they are necessary for the correlations or when they have been

newly established. Some ammonites will be figured because of their stratigraphic or palaeontologic

importance.

Concerning the spelling of the transcriptions of arabic names, we have adopted the common use as

given on recent maps or as established by national rules. Thus we shall write “Djebel" for Algerian

localities and “Jebel” for Moroccan ones.

Palaeogeographic units between the Mediterranean (Traras Mountains) and the Sahara

From north to south, the major structural zones can be defined on their palaeogeographic and

structural features, illustrated on a palaeogeographic map for the Toarcian (Fig. 1; see also Fig. 26).

North Africa is classically divided in two major structural domains, north of the Saharian craton.

148

SERGE ELMI ETAL.

Table 1.— Chronostratigraphic and biostratigraphic units used in NW Maghreb (Lower Jurassic = Lias) and explanation of the

abbreviations used on the figures. Remarks on the zonal divisions. 10: identification of the Jamesoni Zone is not easy in

NW Maghreb; 11: the local Demonense Zone (ELMI 1987) is approximately comparable to the European Ibex Zone but

its lower limit is probably older since Tropidoceras appears at the end of the Jamesoni Zone in Europe; 13-15: classic

Tethyan equivalents of. respectively, the Stokesi, Margaritatus and Spinatum Zones; 20-23: cf. Elmi et al. (1993, 1997).

Tableau I.— Divisions chronostratigraphiques et biostratigraphiques utilisees dans le NW du Maghreb (Jnrassique tnferieur =

Lias). Les symboles el abrevialions soul ceux utilises sur les figures. Remarques sur les divisions. 10 : l'identification

de la zone a Jamesoni n'est pas facile dans le NW du Maghreb : II: la zone a Demonense locale (ELMt, 1987) est

approximativement comparable a la zone a Ibex europeenne, mais sa limite inferieure est probablement plus ancienne

car Tropidoceras apparait a la fin de la zone a Jamesoni en Europe ; 13-15 : equivalents tethysiens classiques,

respectivement, des zones a Stokesi, Margaritatus et Spinatum : 20-23 : cf. Elm I et al. (1993, 1997).

STAGES (and SUBSTAGES)

Ammonites Zones

South Tethyan Domain

AALENIAN (Lower) L Aa

MIDDLE JURASSIC

24 OPALINUM Op

LOWER JURASSIC

UPPER UTo

23 AALENSIS Al

22 MENEGHINII Me

21 SPECIOSUM Sp

20 BONARELLII Bo

< (2 MIDDLE MTo

19 GRADATA Gr {

18 BIFRONS Bi ^

LOWER LTo

17 LEVISONI ^

16 POLYMORPHUM Po

I UPPER =

5 DOMERIAN Do

co sr

rf\ n.

15 EMACIATUM Em

14 ALGOVIANUM Ag

13 CELEBRATUM Ce£

3 LOWER =

^ CARIXIAN Cx

12 DAVOEI Da

11 "DEMONENSE" De

10 (JAMESONI) Ja

UPPER U Si

LOWER L Si

UPPER

MIDDLE

LOWER

RARICOSTATUM

OXYNOTUM

OBTUSUM

TURNERI

SEMICOSTATUM

BUCKLANDI

ANGULATA

LIASICUS

PLANORBIS

Regional Markers

Alticarinata

Gradata

Bifrons

■ Sublevisoni

Mirabile Horizon

Celebratum Subzone

Portisi Subzone

appearance of

Tropidoceras

Margarita "Horizon"

Rejectum Interval

— The Rif-Tell domain, part of the Alpine Chain of North Africa (Maghrebids), related to the

opening of the central Atlantic since the Bathonian-Callovian. Before, it appears to belong to the

Tethyan Domain. North of the transect, it includes a composite Oran Basin (GUARDIA, 1975). It

overthrusts the Alpine foreland.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

149

Table 2.— Chronostratigraphic and biostratigraphic units of NW Maghreb (Middle Jurassic = Dogger) and explanations of the

abbreviations used on the figures. Remarks. 41: the range of the Retrocostatum Zone is here considered as extended to

all the Upper Bathonian because Clydoniceras appears as early as the lower Bathonian and because the Discus Zone is

always poorly documented in the Tethyan realm and no reliable equivalent is defined; 44 and 46: local indexes for.

respectively, the Anceps and Athleta Zones (Elmi, 1971a); they are used here because the correlations are not

definitively established. The uppermost Callovian (Lamberti Zone) is not documented in the studied area.

Tableau 2 .— Tableau des divisions chronostratigraphiques el biostratigraphiques utilisees dans le NW du Maghreb

(Jurassique moyen = Dogger). Les symboles el abreviations sont ceux utilises sur les figures. Remarques. 41 : la

repartition de la zone a Retrocostatum est ici consideree comme s'etendant sur tout le Bathonien superieur car

Clydoniceras apparalt des le Bathonien inferieur et parce que la zone a Discus est toujours tres mat connue dans le

domaine tethysien et il n'existe pas d'equivalents clairement definis ; 44 et 46 : index locaux pour, respectivement, les

zones d Anceps et Athleta (Elmi, 1971a); ils sont utilises ici car les correlations ne sont pas definitivement fixees. Le

Callovien terminal (zone d Lamberti) n'est pas connu dans la zone etudiee.

STAGES (and SUBSTAGES)

UPPER JURASSIC

Ammonites Zones

South Tethyan Domain

MIDDLE JURASSIC

UPPER UCa

46 TREZEENSE Tz

O (3 MIDDLE MCa

45 CORONATUM Co

44 ARKELLI Ar

LOWER LCa

43 GRACILIS Cl

42 BULLATUS Bs

UPPER UBt

41 RETROCOSTATUM Re

Q - MIDDLE MBt

40 BREMERI Br

39 MORRISI Mo

38 SUBCONTRACTUS Sc

37 PROGRACILIS Pg

•<

LOWER LBt

36 AURIGERUS Au

35 ZIGZAG Zl

UPPER U Bj

34 PARKINSONI Pa

33 GARANTIANA Ga

32 NIORTENSE Ni

8 S'

m LOWER LBj

31 HUMPHRIESIANUM Hu

30 PROPINQUANS P f

29 LAEVIUSCULA Le

28 DISCITES Di

UPPER UAa

27 CONCAVUM Cc

| «j MIDDLE M Aa

26 BRADFORDENSIS Bd

25 MURCHISONAE Mu

LOWER L Aa

24 OPALINUM Op

Regional Markers

Oraniceras Or

main level with

Ermoceras

Sauzei

Haplopleuroceras

— The Berberids extend south of the Alpine overthrust. They are composed ot three great structural

and palaeogeographic units: the Tlemcen domain, the High Plains and the Atlas (Ksour) domain. To the

south, extends the Sahara Platform or Craton. The Lower and Middle Jurassic successions are given on

tables 3 and 4.

Source:

150

SERGE ELMI ETAL.

Table 3.— Major formal lithoslratigraphic units, successions, facies and environments along the NW-SE transect Traras-

Saharian Atlas - Part 1: Lower Jurassic.

Tableau 3 .— Principales unites lithostratigraphiques (formations) et leurs facies et environnements le long de la transversale

NW-SE Traras-Atlas saharien. I ere partie : Jurassique inferieur.

HIGH .

PLAINS

TLEMCEN DOMAIN

SOUT1 U RN (SEBDOU)

OMBILiC

VAM1A TENOUCHH

BENI BAHDEI

BASIN

in.iriA)

IRAK AS MOUNTAINS

UMAR ROUBANE

SHOAL

S' el ABED

SUBSIDING

OMBILICS

SHOALS AND

RIDGES

HIGH

j’l.ATEAUX;

DOLOMITE

TENOUCHEIil

DOL I

EASTERN

[DECLENE

TRARAS

(LIMESTONES

t (lower

f member)

JEBELNADOR

FORMATION

(Sabkha fades

IKHORCHEFX

* BEDS l

I (Alternating j

1 marls-lst) 3

and oolites)

BAYADA BEDS

JBELAICH

19 Gr

18 Bi SpiAYADA

17 Le E BEDS

—(Alternatinj

16 Po — marls-lst)

Oncolitic

:Limestom

:AIOUN BEN

r^ffrf nSSEDDOURA t

LIMESTONES W 1 -! 1 i 1

MIRA MARLS;

gPSEUDONO-:

qDULAR LSI :

T1SSEDDOURA LST

ZAILOU

ZAILOU LIMESTONES

OULED AMOK

CARBONATES

LIMESTONES

BOUDJENANE

LOWER MEMBER

of the ZAILOU Em

:DETRITAL'.';‘

KOUDIAT EL

BEIA Fm

ini*

■"•'A IN MEET.AH

/-(CONGLOMERATES

■;y;y;y;y;yty:y ; yy

•| RAXSli ION

BEDS

fRIASSIC

VOLCANICS AND DETRETALS

EERNANE * RISE

NORTH

©Beni Ouarsous oncolitic and stromatolitic condensed ferruginous bed (TRARAS)

©No ammonites in the Tlemcen and the High Plains

©WBL : wavy bedded limestones of the Upper Toarcian

©Several cherty levels with Hesperithyris terebratulids

©Rare ammonites

©Including the Ben Serin beds

A-G : "members" of the Am Ouarka Fm.

Source: MNHN. Paris

JURASSIC OF WESTERN ALGERIA

151

SwSftf VOLCANICS AND DETRTTALS t !

Sabkha and associated facies

Slopes and basins

Mainly siliciclastics

BRIDGE

LAMIN1TES

Fm (Rhetian)

Condensed bed

main gaps

main hard grounds

shallow water

(mainly inner carbonate platform)

open sea outer platform and

E3i® platform margin

Source: MNHN, Paris

152

SERGE ELMI ETAL.

Table 4.— Major formal lithostratigraphic units, successions, facies and environments along the NW-SE transect Traras-

Saharian Atlas - Part 2: Middle Jurassic.

Tableau 4Principales unites lithostratigraphiques (formations) et leurs facies et environnements le long de la transversale

NW-SE Traras-Atlas saharien. 2eme partie : Jurassique moyen.

c-<

39 Re ft y/////////////^^^^ y,y/////////////////////^

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

153

AIN

RHEZALA

(basin or

ombilic)

RAKNET

EL-KAHLA

(tectonic

hinge)

ZERGA (+ I li

Ben KHELIL)

(Northern

ombilic)

AIN OUARKA

ERODED

TIFKIRI

NON

EXPOSED

T1EKIKT Em

TENii-rr

. EL..

KLAKH

with

Xq' BOU LERI IFAD

‘ * REEFS AND''

555 LIMESTONES

GUETTAI Fm

Turbidites:

[ANTAR

[DOLOMITE

KERDACIIA

MF.LAH-

SOU IGA

(median

shoal)

FENDI

(SAHARA)

(cratonic

platform)

(Southern

border)

Od El.

ABOD

NVV BORDER

(GUinTAI-

RI1EA)

ATLAS DOMAIN

HIGH

PLAINS

SAHARA

Source: MNHN, Paris

154

SERGE F.LM1 ETAL.

MEDITERRANEAN SEA

shallow carbonate platforms

protected outer platforms,

carbonate ramps

ferruginous outer platform

basins, troughs

nodular facies (rosso

ammonitico-rosso association)

evaporites

FIG. I.— Palaeogeographical map of the North-Western Maghreb during the Toarcian. Localities: AS. Ain Sefra: B.

Boulemane; BIM, Beni-Mellal: BS. Bou Saada; F, Fes; Fi. Figuig; G. Guercif; L. Laghouat; M. Midelt; MC. Mecheria:

ME. Meknes; OU. Oujda; S. Saida; T. Taza; Ti. Tiaret; Tl. TIemcen.

Fig. /.— Carte paleogeographique du Nord Ouest ma glue bin pendant le Toarcien. Localites : AS, Ain Sefra ; B, Boulemane;

BIM, Beni-Mellal: BS. Bou Saada : F, Fes ; Fi. Figuig ; G, Guercif; L. Laghouat: M. Midelt; MC. Mecheria : ME.

Meknes ; OU, Oujda ; S. Saida ; T, Taza ; Ti. Tiaret; Tl. TIemcen.

THE TLEMCEN DOMAIN

The TIemcen Domain (Fig. 2) shows the following main stratigraphic features:

— late development of the initial carbonate platform (late Sinemurian to early Pliensbachian);

— during the late Pliensbachian and the Toarcian: archipelago of isolated platforms (sometimes

emergent) and intervening troughs;

— late transgression on the shoals;

— limited extension of the Middle Jurassic carbonate platform (Aalenian-early Bajocian);

— deep outer platform and basin sedimentation during the late Bajocian-Bathonian;

— siliciclastic turbidites during the Callovo-Oxfordian;

prodeltaic and deltaic sedimentation during the late Oxfordian-early Kimmeridgian;

— late Jurassic shallow carbonate platform.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

155

FIG. 2.— Map of the northern part of the studied transect (Tlemcen Domain and Oran High Plains).

Fig. 2.— Carte de la parlie septentrionale du transect eludie (Domaine tlemcenien el Hautes Plaines oranaises).

Source: MNHN. Paris

156

SERGE ELMI ET AL.

TRIAS

fault

Trias

Fig. 3. Comparisons of the stratigraphic profiles in different sectors of the Tlemcen Domain and of the Oran High Plains.

Each log is a synthesis of several measured field sections.

Fig. 3. Comparaison des series siraligraphiques dans les differents secieurs du domaine tlemcenien el des Hautes Plaines

oranaises. thaque colonne est la synlhese de plusieurs coupes.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

157

The southern border of this area is hidden by the Cenozoic conglomerates (Eocene High Plateaux

Conglomerates; see BENSALAH et al., 1987). It outcrops only in the Tiouli area, south of Oujda

(Morocco). Several palaeogeographic units became distinct inside the Tlemcen domain, mainly during

Liassic to Bathonian times. They will be briefly defined from north to south and their lithostratigraphic

columnar sections are compared on Fig. 3.

The Traras Mountains

These mountains, including the Djebel Fillaoussene, are part of the northern margin of the Tlemcen

Domain. They are the equivalent of the Moroccan Beni Snassene Mountains and are geographically

limited to the south by one of the main depressions of the western Maghreb, ranging from Guercif to the

Mleta Plain (south of Oran). From the Early Jurassic to the Bathonian. the Traras are composed of

several small subsiding basins in a network of stable shoals and ridges (Guardia. 1975; ELMI 1978,

1981b; AMEUR, 1978, 1988; BENHAMOU, 1983). Two kinds of composite lithologic successions are

given here: one for the thick series of the subsiding umbilics, the other for the thin and incomplete series

of the shoals or transition zones (Figs 4-5). The geometry of the main units is controlled by three

tectonic trends: N020°, N040°-050° and N110°-150°. The relative movements of the faults changed

during time and strong modifications occurred at the beginning of the Domerian, during the early

Toarcian and throughout the Aalenian-early Bajocian. causing the episodes of differentiation and mosaic

stages of development (for a more complete definition: see BENSHILI & ELMI, 1994; Elmi, 1996b).

The Jurassic transgression is often marked by spectacular breccias and conglomerates at the base of

the Zai'lou Formation (Carixian) (Fig. 6a). In the Beni Mishel, this conglomerate consists in granitic

blocks deposited in coarsely quartzose limestones at the foot of littoral cliffs (Djerf el Kebir Member,

Fig. 9a. b).

Tectonic unconformities are well documented:

— between the Zai'lou Limestones Formation (shallow platform carbonates mainly of Carixian age

with the famous “calcaires a grands lamellibranches” facies (large pelecypods); AMEUR, 1978;

BENHAMOU, 1986a) and the Tisseddoura Formation (cherty limestones with Domerian brachiopods);

— at the end of the Domerian and during the Toarcian, unconformities are spectacular between the

Tisseddoura Formation and the ferruginous crusts related to the Sekika ammonitico rosso (Elmi, 1981b;

see Figs. 1, 2 and Fig. 6b to e), in thelDjebel es Sekika sector (Beni Ouarsous; BENHAMOU, 1986b);

— in the lower Toarcian basinal facies (Bayada Formation), tectonic instability is illustrated by mass

sliding (Fig. 9d) and by turbidites;

— between the top of the ammonitico rosso (topmost Toarcian to lower Aalenian) and the

Humphriesianum Zone in the Djebel Gorine (BENHAMOU. 1983) (Fig. 9c).

The general instability led to the widespread development of reworked megabreccias, slumps and

turbidites (AMEUR & Elmi, 1981), especially during the early Toarcian and the early Bajocian

(calciturbidites of the Fenakech Marls Formation). Local tectonics are documented until the Callovian:

the Saida Clays Formation rests locally directly on the Zai'lou Limestones in the Sekika-Gorine region

(GENTIL, 1908; GUARDIA, 1975) where they include megabreccias reworking Liassic and Palaeozoic

pebbles (ELMI & BENEST, 1978) (Fig. 6f).

Two main associations of facies can be distinguished in the Toarcian of the small basins ol the

northern Tlemcen Domain, in a zone which is transitional to the Alpine Tell. They belong to two

formations: the marl-dominated Bayada Formation (alternating marls and micntic limestones) and the

predominantly nodular Sekika ammonitico rosso Formation.

Bayada Formation: basinal environment; alternating marls and limestones in thin decimetric beds, more

marly at the base; colour grey or greenish, sometimes pink. The marls are silty and strongly bioturbated,

with poor microfauna. The ammonite fauna consists of small individuals owing to the restricted

conditions developed in these small basins (umbilics).

158

SERGE ELMI ET AL.

Traras Mountains.

Reduced successions (Ex.:

Fillaoussene)

GAP OF THE

UPPER BATHON1AN

■s

Fig. 4.— Synthetic profile of the reduced Middle and Upper Jurassic series of the Central and Eastern Traras Mountains,

especially in the Fillaoussene Range (Mahassar. Ain Tolba) and in the Beni Mishel. This succession sustains abrupt

lateral variations.

Fig. 4 .— Succession synthetique du Jurassique inferieur el moyen dans les series reduites des Traras orientaux el centraux en

particulier dans les regions du Fillaoussene (Mahassar. Ain Tolba) el des Beni Mishel. Cette serie montre des

variations laterales abruptes.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

159

Fi G 5 _ Synthetic profile of the Lower and Middle Jurassic (up to the Bathonian) thick succession of the Western Traras

Mountains (Sidi Bou Djenane. Ain Killoun). This succession is everywhere alfected by sedimentary and tectonic

instability (erosion, gravity flows, turbidites).

Fig. 5.

— Succession synthetique du Jurassique inferieur el moyen (jusqu'au Bathonien) dans les series dilutees des Traras

occidentalix (Sidi Bou Djenane. Ain Killoun). Les variations laterales sont rapides et spectaculaires en raison de

I'instabilite sedimentaire el tectonique (erosion, flux gravitaires, turbidites).

Source MNHN Paris

160

SERGE ELMI ETAL.

Sekika ammonitico rosso Formation (previously known as Traras ammonitico rosso: we change the

name here in order to avoid confusion with the Traras Limestones Formation of the Aalenian-Bajocian

and to match international usage): largely marly in the lower part (Fig. 6b), with thin centimetric

calcareous beds and residual nodules, changing upwards to bioturbated and subnodular limestones. On

the shoals (Figs 7-8), the formation is capped by oncolitic and ferruginous limestones dated to the

Opalinum Zone (Beni Ouarsous oncolitic bed: BENHAMOU, 1983).

Fig. 6 .— Details of some Jurassic outcrops of the Eastern Traras Mountains (Beni Mishel and Beni Ouarsous, Algeria, Tlemcen

Wilaya).

a. Transgression of the basal Zai'lou Limestones Formation (lower Pliensbachian = Carixian) on red beds of possible Triassic-

Hettangian age. Heterometric and heterogeneous conglomerate reworking Palaeozoic (quartzites, schists) and lower Liassic

(tidal carbonates) pebbles at the base of shallow platform carbonates. Road C.W, 213 at the foot of Diebel Anina Boudjelil near

Djebel es Sekika and Souk el Arba. Coll. Elmi, 73A12.

b. Sekika ammonitico rosso Formation. The lower part (nodular alternating grey marls and limestones; basal Sublevisoni

Subzone) is not exposed here. The outcrop shows the red median part (middle Toarcian, Sublevisoni Subzone) which is marly

dominated. The calcareous beds become more frequent upward and they present a pseudonodular aspect due to an intense

bioturbation. (See Fig. 9c). Oued el Merzouf on the south east side of Djebel Gorine. Coll. Elmi, 83DZ637.

c, “Neptunian" dyke open through Carixian Zai'lou Carbonates and filled by Toarcian pink micrite. It is interpreted as an

extensional marker (see also: Figs 7 and 8). Souk el Arba near es Sekika Djebel. Coll. Elmi, 73A17.

d, e, Ferruginous and probably stromatolitic red crust (probable middle Toarcian) coating a palaeorelief in “marches d’escalier”

(steps) dug out in the cherty limestones of the upper Pliensbachian (Domerian Tisseddoura Formation). The grey blocks on the

surface are cherts of the Tisseddoura Formation, exhumed by the pre-Toarcian erosion, and Palaezoic quartzite pebbles.

Between the crust and the Domerian limestones, there remain traces of nodular grey limestones with rare ammonites (Hildaites)

of the lower Toarcian (Levisoni Zone). These remain traces are preserved on horizontal and vertical surfaces. These data

document the occurrence of a second erosional phase which had taken place at the end of the Levisoni Zone after a first

covering of the palaeorelief. Laterally, the succession rapidly becomes complete: Sekika ammonitico rosso Formation, similar

to that illustrated on Fig. 6b, developed in less than 500 m. Change to the basinal Bayada Marls Formation occurs in less than 2

km. Same locality as Fig. 6c; the two outcrops are ten meters distant. Coll. Elmi, 73A22-23.

f. Heterometric and heterogeneous conglomerate near the base of the Saida Clays Formation (lower Callovian - Palaeozoic

quartzites. Liassic or perhaps Bajocian limestone pebbles). Track from Souk el Arba village to Djebel es Sekika. Coll. Elmi

FlC. 6.— Details de quelques affleurements jurassiques des Monts de Traras orientaux (Beni Mishel et Beni Ouarsous Algerie

Wilaya de Tlemcen ).

a, Transgression de la base de la Formation des Calcaires compacts de Zai'lou (Pliensbachien inferieur = Carixien) sur des

couches rouges d‘age probablement triasico-hettangien. Le conglomerat de base des carbonates de plate-forme peu profonde

comprend des elements heterometriques el heterogenes remanies aussi bien du Paleozoique (quartzites, schistes) que du Lias

injerieur (carbonates lidaux). Route C.W. 213 ; Souk el Arba, au pied du Djebel Anina Boudjelil pres du Diebel es Sekika et

Souk el Arba. Coll. Elmi, 73All.

b Formation de l’ammonitico rosso du Sekika. La partie inferieure (alternance de calcaires et marnes grises noduleux ; base

de la sous-zone a Sublevisoni) n affleure pas. L'affleurement expose la partie rouge mediane de la formation ou les marnes

sont abondantes (Toarcien moyen, sous-zone a Sublevisoni). Les bancs calcaires deviennent plus epais et plus rapproches vers

le haul (Fig. 9c) oil ils prennent un aspect pseudonoduleux. La bioturbation est importante sur toute I'epaisseur Oued el

Merzouf, flanc Sud Est du Djebel Gorine. Coll. Elmi, 83DZ637.

c Fissure ("dyke neptunien") ouverte dans les Calcaires de Zai'lou (Carixien). Elle est comblee par des micrites roses du

CiFfH, C 7 f‘ f 7 ln,er P rete comme marqueur d'extension (voir aussi: Figs 7 et 8). Souk el Arba pres du Djebel es Sekika.

d, e Croute ferrug,neu.se d ongine vraisemblablement stromatolithique, dage probablement toarcien moyen. Elle fossilise un

paleoreliej en marches d escaliercreusees dans les calcaires a silex du Pliensbachien superieur (Formation domerienne du

lisseddoura). Les blocs gris visibles sur les surfaces horizontales des bancs sont des silex de la Formation du Tisseddoura

degages par I erosion ante-toarcienne et des fragments de quartzites paleozoiques. Des lambeaux de calcaires micritiques

noduleux gris sont conserves enlre la croute et les calcaires du Domerien ; ils ont livre de rares Hildaites du Toarcien inferieur

ZZ e u lambeaux sont preserves sur les surfaces verticales et horizontales. Le colmatage du paleorelief s'est

InnJZJr' ° ", Le f’ ,som - ^ succession toarcienne se complete rapidement sur les flancs de

h, P F n 7- d€ , S ° Uk elArba \ de ‘a formation de 1’ammonitico rosso du Sekika, similaires d cedes illustrees sur

L L nitr devel ?PP!! n, , en n ! oms % 500 m e < 1* Passage au facies bassin (Formation de Bayada) intervient en mains de 2

Km. Localite . voir jig. 6c. Les deux affleurements sont distants de 10 metres. Coll. Elmi, 73A22-23.

h ^ r °Sene pres de la base de la formation des Argiles de Saida (Callovien inferieur -

' Toll.E^, P 73A33 ,qUeS ' 8 ° ^ Ca C “ ,reS has,( l ues 011 P el " etre bajociens). Sender entre Souk et Arba et le Djebel Sekika.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

161

MNHN Paris

162

SERGE ELMI ETAL.

EARLY CALLOVIAN

F G ‘ 7 ' Transverse; profiles through ihe Souk el Arba palaeostruclure (Beni Ouarsous near Djebcl es Sekika in ihe Traras

Mountains). The palaeorelief was differentiated progressively from the end of the Toarcian (A) and it remained

N'rmi'rv'invi nni ZZZ'n (B) ' ,I’ C submer g‘ n g of the structure began during the early Bathonian but was

terminated only during the Callovian. Dips, unconformities and erosion figures have been drawn in the field. I. relative

sea level during the maximum flooding (Sublevisoni Subzone of the middle Toarcian); 2. relative sea level at the

S" ln 8 a " d at 'he end of the Toarcian and during the early Aalenian; a. "Lithiotis” limestones of the top of the Zatlou

Formatton (early p l |e nsba c hian - Carman): b, cherty limestones of the Tisseddoura Formation (late Pliensbachian.

early to middle Domenan); c.d.e. ammonitico rosso ol Sekika Formation: c. nodular limestones with reworked pebbes"

d. breccias; e. fissures ( neptunian dykes") and stromatolitic crusts; f. Sekika Marls Formation (early Bathonian)’

beginning by a condensed bed yielding Prohecticoceras sp. A and B (Elmi. 1971b) on top of the anticline; g, Saida

Clays Formation (Callovian) (from Elmi. 1981b: fig, 9). B

FIG. 7.- Coupes transversales de la paleostructure de Souk el Arba (Djebel es Sekika. Beni Ouarsous. Moms des Traras) Le

RmZtn, R fr?‘{ erenC ' e P r °S re f‘ ve "'ent depuis la fin du Toarcien (A) e, esi demeure preeminent jusquau

Bat omen (B). L ennoyage progress,j de la structure debute an Bathonien inferieur mais ne sera termine cpte durant le

Callovten. Pendages, dtscordances et figures d’erosion ont ete traces par observation directe sur le terrain. I. niveau

tltufT c '"’" aX "" U "\ de J U ' ra 1 fsession toarcienne (sous-zone a Sublevisoni du Toarcien mover,) ; 2, niveau

Fnrmodnu L 7 . , ,Pr “ £ fi £- du T ° arc,en # pendant PAalenien inferieur ; a. calcaires d "Lithiotis ” de la

— * Zad0U <P^nsbachten infer,eur = Carixien) ; b. calcaires a silex de la Formation du Tisseddoura

Pliensbacluen super,eur. (Domenen infer,eur-moyen): c.d.e. ammonitico rosso du Sekika : c. calcaires nodideux

ZTZ m a ,en,S r /- ma '"1 bricheS ■’ e ’ fenteS C ' dykes ne P ,un ' en s") et creates stromatolithiaues ; f Marnes

du Sekika (Batlionien inferieur) debutant par un niveau condense livrant Prohecticoceras sp. A et B (Elmi 1971b) • p

Argiles de Saida (Callovien) (d apres ELMI. 1981b : fig. 9). '

The tsopach map of the Toarcian deposits shows spectacular variations in their thickness (Fie. 10)

allowtn® recognition of several basins, ten kilometers long: Ain Killoun (Mellala), Beni Ouarsous, Beni

Mtshel and Boudjenane. On the bottom of these basins, the microfauna and the dwarfed ammonite and

brachtopod taunas indicate that the environment became progressively restricted. They give a good

model ol the “umbilic" (or umbilicus stage; see Boutakiout & Elmi. 1996; Elmi. 1996bf An umbilic

shows deepening because sedimentation does not keep pace with subsidence. It follows the rifting phase

and requires active tectonic control. It represents a juvenile stage in the development of the basin,

resulting in a distinct partitioning of the sea-bottom. In the areas studied, the anoxic or hypoxic early

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

163

® LATE TOARCIAN

® EARLY CALLOVIAN

Fig. 8 .— Submergence of the palaeorelief on the axis of the Souk el Arba structure during the Toarcian and the early Aalenian.

See Fig. 7. Other symbols: gb. cherty and quartzose limestones (Domenan); c.e, calcareous ammonitico rosso capped

by ferruginous oncolites and crusts with Leioceras sp. (Beni Ouarsous Oncolitic Beds; Benhamou. 1983). During the

early Aalenian the top of the structure was emergent (tidalites. mud-cracks, vadose diagenesis) and the tilting to the

nearby basin was rapid (from Elmi, 1981b: fig. 11).

FlG 8 — Evolution des depots stir I'axe de la paleostructure de Souk el Arba pendant le Toarcien el le debut de I Aalenien.

' Pour les svmboles: voir Fig. 7. En plus : gb. calcaires a grains de quartz era silex ( Domenen): c.e ammonitico rosso

calcaire se terminant par le "niveau a oncolithes ferrugineux des Bern Ouarsous (Benhamou. 1983) a ammonites

(Leioceras sp.) et a surfaces encroutees. Durant FAalenien inferieur. I'axe de la paleostructure jut alors soumts a des

emersions temporaires comme en temoignent des mud cracks et des tidalites d figures de dessiccation. Le passage au

bassin a dii etre rapide le long d'une pente nettement marquee (d'apres ELMI. 1981b: fig. II).

Toarcian event is widespread, but the preservation of organic matter is limited by the physiography ot

the basins.

These observations and the resulting maps can be used as models of the dynamics ot the umbthcs as

well as of the hinge zones between other kinds of troughs and their margins. The telescoping ot he

isopachs gives good evidence of tectonically controlled steep slopes They demonstrate also the

existence of such small basins which are good traps for organisms as well as or organic matter They

can be easily compared with structural pattern known elsewhere during the fitting stages espec al

the Apennines (ELMI & AMEUR, 1987), during the Early Jurassic, and in the North Sea dunn c the Late

Jurassic.

The tectonic instability continued in the Traras all along the Bajocian (frequent gaps, ^citurbidites

in the Fenakech Formation, slumping and sliding in the Traras Limestones Portion,

conglomerate at the base of the Saida Clays Formation (Fig. 60 (Elmi & BEMEST 197 ^ AMEUR 19^8).

The marly sedimentation appeared during the early Bajocian in the western subsiding subbas ns (Fig. 5

Fenakech Formation with alternating marls and marly limestones) followed by the Am Killoun ai s

Source .

164

SERGE ELMI ETAL

Formation (upper Bajocian) and the lower Bathonian Sekika Marls Formation. After a gap of the upper

Bathonian. sedimentation resumed with the onlapping of the marl-dominated Saida Clays Formation.

This partly turbiditic formation sealed the previous palaeoreliefs and shoals. It can rest on the lower

Bathonian (centres of the umbilics) or on older formations ranging from the Bajocian to the Carixian (in

the Sekika - Gorine - Sidi Sefiane area; GENTIL, 1908; GUARDIA, 1975; ELMI, 1981b; BENHAMOU

1983; AMEUR, 1988).

Fig. 9.— Lower and Middle Jurassic of the Traras Mountains and the Jurassic transgression on the Rhar Roubane horst

(Algeria, Tlemcen Wilaya).

a. b, Djerf el Kebir Conglomerates (lower member of the Zai'lou Formation). Metric blocks of hercynian granite sedimented in

disorder in a marly and quartzose limestone containing rare belemnites (probable early Pliensbachian = Carixian). They have

been accumulated at the toe ot a cliff and concealed during the Pliensbachian transgression. Upwards, they are organized in a

thinning up and shallowing up sequence passing to the Taouia Oolite Member. Bern Mishel basin. Dierf el Kebir near Zai'lou

Coll. ELMI, 76CA7A and 83DZ609.

c. Angular discordance of the Stephanoceras beds (Traras Limestones) (Humphriesianum Zone) on the erosion surface of the

Sekika ammonitico rosso, capped by the Beni Ouarsous Oncolitic Beds. Lower Aalenian Opalinum Zone Oued el Merzouf

near Djebel Gorine. Coll. Elmi 82DZ337.

d. Slumping in ihe Traras Limestones Formation. The transported material consists of synsedimentary marly limestones and

marls belonging to ihe same environment. The slumps are sealed by a discordant decimetric bed (black arrow) Lower Toarcian

(Levisoni Zone). Sidi Boudjenane Basin (or Umbilic). Chabet Sof Ahmed, SW Traras. Coll. Elmi, 85DZ89.

e. Discordance, transgression and onlap of the Bajocian Deglene Dolomites (I) on the Upper Palaeozoic (2). The vertical

u CI mt- (3) consists of Dinantian dolomites (see Fig. 12). The palaeorelief is submerged during the lower Bathonian by the

Moul el Tagga Formation (4). In the background: Palaeozoic hills (Devonian-Dinantian. sandstones and argilites) of the Diebel

Fernane Elevation pomt 1222, “Fernane Pass" (Lucas, 1942). Ras Afourgate. East of Sidi Yacoub, Rhar Roubane Mountains.

f. Discordance and transgression of the Liassic beds on the irregularily eroded Palaeozoic rocks (Silurian'7-Devonian). Residual

pa'aeoreliefs (Palaeozoic quartzites) are concealed by the Zai'lou Limestones Formation (Carixian) which are only preserved on

he bottom of the gull.es (1). The top of the cliff corresponds to the bioclastic limestones with Protogrammoceras celebration

d Orbigny) of the Tisseddoura Formation (type section, lower Domerian) (cf. Elmi. 1977a. 1983) (2) and to the Belai'ch Beds

(type-section Toarcian) (see Fig. 13a). The upper parts of the palaeorelief are concealed by the onlap of Moul-el-Tasea

Formation which is locally uncomformable. Note the strong reduction of the cliff at the track way. Djorf Tisseddoura Cliff

84DZ805 ° d tfaCk r ° m KCt 10 S ' d ‘ D ^ l,lal1 ’ eastern Rhar Roubane horst near Khemis of the’Beni Snouss. Coll. Elmi

F/G. 9.— Jurassique inferieur el moyen des Monts des Traras el transgression jurassique sur le horst de Rhar Roubane

(Algerie, Wilaya de Tlemcen).

a. b. Conglomerats des Djerf el Kebir (membre inferieur de la Formation de Zai'lou). Blocs metriques de granite hercynien

sedimentes en desordre dans un calcaire argilo-quartzeux contenant de rares belemnites (probablement du Pliensbachien

inferteur - Carixien). II s'agit de la fossilisation d'un eboulis forme au pied d'une falaise tors de la transgression

phensbacluenne. Les assises superposies s’organisent en une sequence qui enregistre a lafois Vaffinement des sediments et la

diminution de la profondeur (Membre des Calcaires oolithiques de Taouia). Bassin des Beni Mishel. Djerf el Kebir pres de

Zai'lou. Algerie. Coll. Elmi. 76CA7A and 83DZ609.

c. Discordance angulaire des couches a Stephanoceras (Calcaires des Traras) (Zone a Humphriesianum) sur la partie

superieure erodee des mveaux oncolithiques des Beni Ouarsous (zone a Opalinum. Aalenien inferieur) qui terminent

I ammonitico rosso du Sekika. Oued el Merzouf pres du Djebel Gorine. Coll. Elmi. 82DZ337.

d. Glissements dans la Formation des "Calcaires des Traras". !ls mettent en jeu des blocs de calcaires argileux et de marnes

appurtenant au meme environnement. La cicatrisation est realisee par un banc de calcaire micritique (fleche noire). Toarcien

inferieur (zone a Levisoni). Chabet Sof Ahmed. Bassin (ombilic) de Sidi Boudjenane, Traras 5IV. Coll. Elmi, 85DZ89.

e. Transgression et discordance de la Dolomie de Deglene du Bajocien (1) sur le Paleozoi'que superieur (2) (cf. Fig. 12) ou la

dolomte dinantienne forme un ecueil (3) qui ne fut enfoui que tors du Bathonien inferieur (Formation de Moul el Tagga 4) A

amere plan : colltnes paleozo'iques (gres et argilites du Devono-Dinantien) du Djebel Fernane. Point cote 1222. connu sous

du Fernane " (Luc:as - l942 >- Barriere du Ras Afour. a FEst de Sidi Yacoub. Monts de Rhar Roubane. Coll.

f. Transgression et discordance des assises liasiques sur les formations paleozo'iques erodees (Siluro?- Devonien). Les

quartzites paleozoiques constituent des reliefs residuels qui sont cicatrises par le depot des Calcaires de Zai'lou du Carixien

Les dermers sont settlement preserves dans le fond des depressions (I). La partie superieure de la falaise calcaire correspond

a des calcaires bioclastiques a Protogrammoceras celebratum (d’Orbigny) du Domerien inferieur (coupe-type de la Formation

des Calcaires du Tisseddoura ; cf. Elmi. 1977a. 1983). Les “Calcaires oncolithiques du Belai'ch", affleurent au sommet de la

falaise (coupe-type. Toarcien) (voir Fig 13a). Les points les plus hauls du paleorelief sont cicatrises par la disposition en

debordement (onlap) de la Formation du Moul-el-Tdgga (2) qui est localement discordante. Noter la forte reduction de la

falaise au niveau ou passe la piste. Falaise du Djorf Tisseddoura, le long de I’ancienne piste du Kef a Sidi Djillali Horst

oriental de Rhar Roubane pres du Khemis des Beni Snouss. Coll. Elmi, 84DZ805.

JURASSIC OF WESTERN ALGERIA

165

Snume MNHM Paris.

166

SERGE ELMI ETAL.

F ' G ' ‘^| T A arC ^V' IUS N.f n 8 / h r/' m , h ' llCS differenIia,ed within the Traras Mountains. Small basins (Beni

Ouarsous, Bern Mishel Ain Killoun-Mellala. Boudjenane) rapidly subsiding and deepening have not been balanced by

5 r^iTh" " a d r r L nS th tr ary J° arcian and are S° od examples of the "umbilic concept". The broken lines

NNF (1 Honahie shmIv sw yf,' C p l C resistant shoals are oriented along three main directions (solid lines): SSW-

Rnl i f n r-'M ^ NE( ?' ^ lllaoussen e-Nedroma shoal); WNW-ESE (3. Ain Tolba shoal). A. Cap Noe fault;

B. Dahr ed Diss fault; C. Nedroma fault (nomenclature of the faults from Guardia, 1975 and Ameur. 1988).

Fla C .“ r ! e des isopaquesduToarcien Ulus,ran, les ombitics (Moms de Traras). Ces pe,i,s bassins (Beni Ouarsous. Beni

Mishel. Am Killoun-Mellala. Boudjenane) on, subi. pendant le Toarcien inferieur. un enfoncement el un

approfondissement raptdes qu, nefurent pas compenses par la sedimentation. Ils fournissent un bon exemple de la

notion d ombiltc. Les tiretes indiquent la direction d’allongement de ces ombilics. Les seuils (axes) resistant v se

repamssen, selon trots directions (lignes continues) : SSW-NNE (1. axe de Honaine) ; SW-NE (2. axe Fillaoussene-

Nedroma) ; NNW-ESE (3 axe d Am Tolba) ; A. faille du Cap Noe : B. faille de Dahr ed Diss : C. faille de Nedroma

(nomenclature des failles d apres Guardia. 1975 et Aueur, 1988).

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

167

The Rhar Roubane and TLemcen Mountains

They are also divided into several palaeogeographic units, defined by the structural pattern and

marked by important and well documented Jurassic movements. Westward, the Rhar Roubane

Mountains extend to the Moroccan border, and are limited to the east by the Tafna fault (lineament).

Their median part consists of a Palaeozoic horst bounded by Upper Jurassic plateaux, and covered by

thin Lower Jurassic transgressive beds. The different sectors will be briefly described from north to

south in order to summarize the previous published data (LUCAS, 1942, 1952. 1966; AUGIER, 1967;

ELM1, 1997).

THE SUBSIDING NORTH MARGIN

Oujda Trough, adapted from LUCAS (1942. 1952) ("vasiere Oujda-Sebdou”). This trough or umbilic

may be the prolongation of the subsiding Zekkara Zone of east Morocco (northern Oujda Mountains),

but the Lower and Middle Jurassic does not outcrop in Algeria.

THE AXIAL Rhar Roubane Shoal

It is divided into two parts by a major transverse palaeorelief (Fernane Shoal along the Beni Bou Said

Fault; LUCAS, 1942; ELMI, 1973a).

The West Deglene Sector

In this area, the lower Pliensbachian (Carixian; Za'flou Limestones) consists of shallow carbonates

resting on the Palaeozoic basement and it can be locally missing. The Toarcian is made of shallow ramp

carbonates and marls (Khorchef Beds) with rare ammonites ( Hildoceras\ Sublevisom Subzone. Bitrons

Zone) and small-sized brachiopods ( Soaresirhynchia houchardi (Davidson) and Homoeorhyncma

tifritensis (Dubar)). These two levels are respectively correlated with the Levisom and the Bitrons

ammonite Zones. At the top of the Khorchef beds, wavy-bedded limestones (WB on Tables 3 and 4) are

attributed to the upper Toarcian by comparison with well dated areas such as the Saida Mountains (ELMI

el al ., 1985). Upward, the shallowing of the environment continued during the deposition of the Deglene

Dolomite Near its base, rare brachiopods (Stroudithyris pisolithica (Buckman) and S. frederici roman t

(Roche)) document the Aalenian (MEKAHU et al, 1993) but the major part of the formation is made of

oolitic grainstones and of tidalites with desiccation markers (ELMI & AUMERAS, 1985, MEKAhLI, 1 )88).

The upper Bajocian is probably missing and the overlying Deglene Oolitic Ironstone rests

unconformably on the weathered top of the Dolomites (N.B.: these dolomites have been worked as lead-

zinc ore at Deglene and in the well known El Abed and Touissit-Bou Beker Mines along the western

ed i, e of the Rhar Roubane Mountains). The Deglene Oolitic Ironstone (Mekhali et al ., 1 994) is an

ammonite rich level, thickening to the east (from 2 to 50 m in 4 km between Deglene and Fernane-Sidi

Yacoub- LUCAS. 1942). It ranges from the lower Bathoman (Zigzag Zone) to the top of the middle

Bathonian sensu gallico (Bremen Zone). The most significant marker ol the early Bathoman (Zigzag

Zone and, possibly, beginning of the Aurigerus Zone) is Oraniceras hamyanense Flamand One

specimen from Jorf Henndia between Sidi Mohammed and Sid. Jabeur along the OuedI Mellah (Oujda

Mountains, Morocco), coming from the same formation, is figured here (Fig. l ib)' bec«Be it show,

clearly the carina-like shape of the ventral edge as in the types which come from the Ksour El Harcha a

locality (Flamand. 1911: PI. VII, Figs 10-13). This feature indicates a strong difference with the classic

parkinsonid Gonolkites.

The upper Bathonian (Retrocostatum Zone) is missing as it is usual in all the Tlemcen Domain (ELMI

1971a, 1973b).

The Callovian begins with another oolitic and ferruginous decimetric bed yielding some

bullatum (d'Orbigny) and several specimens of the subgenus Macrocephalites. It is overlain by the thick

168

SERGE ELMI ETAL.

beds of the Saida Clays Formation (rhythmic turbiditic sandstones, marls and ferruginous limestones)

well dated from the Gracilis Zone in their lower part (LUCAS, 1942; ELMI, 1971a, b) and ranging into

the lower Oxfordian at their top during the maximum deepening stage which was followed by a rapid

shallowing (ELMI & BENEST, 1978).

The tectonic control is well documented near the Fernane Pass (Elevation Point 1222; Figs 9e and

12) where the shallow marine Deglene Dolomite onlaps the Palaeozoic palaeoreliefs. This formation has

been faulted, probably during the late Bajocian and the fault scarp has been levelled and sealed by the

the lower Bathonian (Moul el Tagga Silty Limestones Formation) well dated by newly collected faunas

(numbers indicating the place of the faunas are spotted on Fig. 12: n° 32: Parkinsonia (Gonolkites)

convergens Buckman, Morphoceras (Ebrayiceras?) parvum Buckman, Planisphinctes sp.,

Nannolytoceras tripartitum (Raspail), Holcophylloceras sp. at the top of the fault; n° 33, at the top of the

down-faulted block: P. (G.) cf. convergens (Buckman) associated with brachiopods -Burmirhynchia

termierae Rousselle and Capillirhynchia ardescica (Rollier)- and bivalves commonly known from the

more neritic environment of the Ksour Mountains, such as Ctenostreon palati Flamand, indicating the

proximity of shallow seamounts; n° 36, in the beds sealing the faulted stucture: Procerites subprocerus

Buckman, Asphinctites cf. polysphinctus Dietl, “ Morphoceras” aff. pingue De Grossouvre (inner whorls

very involute and smooth body-chamber), Siemiradzkia aurigera (Oppel) in Sturani, Oxycerites

yeovilensis (Rollier), Holcophylloceras sp.; this fauna is difficult to correlate (top Zigzag or lower

Tenuiplicatus Zones).

The variability of the Morphoceratids seems to be different from that of their european equivalents.

For this reason, we figure here an atypical specimen of “Morphoceras"parvum from bed 32 (Fig. 1 la).

Fig. 11.— Jurassic ammonites of the Rhar Roubane (Tlemcen W., Algeria), Oujda (Eastern Morocco) and Ksour Mountains

(Naama W., Algeria). All figures = x 1.

a .Morphoceras parvum Buckman. Lower Bathonian. Moul el Tagga Formation. Bed 32. Height 1222 near Sidi Yacoub,

Fernane Pass (Rhar Roubane Mountains). Coll. ELMI, Univ. Lyon, n° 299668.

b, Oraniceras hamyanense Flamand. Lower Bathonian Deglene Oolitic Ironstone. Jorf el Henndia near Sidi Mohammed (Oued

Melah, Sidi Jabeur, Oujda Mountains). Specimen showing the carina-like ventral area. Coll. ELMI, Univ. Lyon, n° 299667.

c, Hammatoceras roubanense Elmi nov. sp. Holotype. Middle Toarcian Gradata Zone. Alticarinata Subzone. Bela'ich Oncolitic

Limestones (“banc carie"). Djorf Tisseddoura, Sidi Yahia ou Djabert, Khemis des Beni Snouss, Rhar Roubane Mountains. Coll.

Elmi, Univ. Lyon, n° 299800.

d, Hammatoceras roubanense Elmi nov. sp. Paratype. Same locality and bed. Coll. Elmi, Univ. Lyon, n° 299801.

e, Psiloceras (Caloceras) sp. Lower Hettangian. Chemarikh Dolomite Formation. NW slope of Djebel Chemarikh. Ain Ouarka

near Ain Sefra (Ksour Mountains). Coll. Mekahli, Univ. Lyon, n° 299671.

f, Pleuroceras cf. solare (Phillips). Upper Pliensbachian (Domerian), lower Emaciatum Zone. Calcareous equivalent of the

topmost Ain Ouarka Formation (member G). Raknet el Kahla, 2 km NE of Ain Ouarka near Ain Sefra (Ksour Mountains). Coll.

Mekahli, Univ. Lyon. n° 299669.

Fig. 11.— Ammonites jurassiques des Monts de Rhar Roubane (W. de Tlemcen. Algerie), d’Oujda (Maroc oriental) et des

Ksour (W. de Naama, Algerie). Toutes figures = x 1.

a, Morphoceras parvum Buckman. Bathonien inferieur. Calcaires microgreseux de Moul el Tagga. Banc 32. Cote 1222, col du

Fernane pres de Sidi Yacoub (Monts de Rhar Roubane). Coll. Elmi, Univ. Lyon, n 0 299668.

b, Oraniceras hamyanense Flamand. Bathonien inferieur. Oolithe ferrugineuse de Deglene. Jorf el Henndia pres de Sidi

Mohammed de I'Oued Melah pres de Sidi Jabeur. Monts d'Oujda. Exemplaire montrant bien I'aspect carene de Faire ventrale.

Coll. Elmi, Univ. Lyon, n°299667.

c, Hammatoceras roubanense Elmi nov. sp.. Holotype. Toarcien moyen. Zone a Gradata. Sous-zone a Alticarinata. Calcaires

oncolithiques du Belaich (banc carie). Djorf Tisseddoura, Sidi Yahia ou Djabert, Khemis des Beni Snouss, Monts de Rhar

Roubane. Coll. Elmi, Univ. Lyon, n° 299800.

d, Hammatoceras roubanense Elmi nov. sp. Paratype. Mernes localite el niveau. Coll. Elmi, Univ. Lyon, n° 299801.

e, Psiloceras (Caloceras) sp. Hettangien inferieur. Dolomie du Chemarikh. Flanc W du Djebel Chemarikh, Ain Ouarka pres

d'Ain Sefra (Monts des Ksour). Coll. MEKAHU, Univ. Lyon, n°299671.

f, Pleuroceras cf. solare (Phillips). Pliensbachien superieur (Domerien), partie inferieure de la zone a Emaciatum. Equivalent

calcaire de la partie terminate de la Formation d'Ain Ouarka (membre G). Raknet et Kahla, a environ 2 km au NE du village

d'Ain Ouarka pres d'Ain Sefra (Monts des Ksour). Coll. Mekahli, Univ. Lyon, n° 299669.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

169

170

SERGE ELMI ET AL.

Fig. 12.— Semi-diagrammatic view of the Femane Pass (height 1222) illustrating the onlap of the Bajocian and Bathonian beds

on the Palaeozoic basement. Western Deglene Sector of the Rhar Roubane axial shoal, near its limit with the eastern

Tisseddoura Sector.

A. Schists and quartzites, probably of the Devonian-Dinantian, dipping vertically. They are strongly weathered and rubefacted

on several meters; B. Dinantian dolomite; C, Deglene Dolomite; Aalenian - lower Bajocian. The dolomites (oodolosparites)

result from the crystallisation of oolitic grainstones and packstones; with channelized debris flows reworking pebbles made of

palaeozic quartzites. The lower part is pink - purplish-blue, due to the washing of Palaeozoic palaeosoils (n° 1). Pression-

soiution features are common (vadose diagenesis). Birdeyes, algal laminations, oncolites and desiccation breccias become

frequent slightly toward the South (between Sidi Yacoub and elevation 1222). Mass flows of big carbonate and quartzite

pebbles indicate the importance of the topographic slopes (gravity-flows). D. Moul-el-Tagga Silty Limestones (early

Bathonian) represented here by thinning-up alternances of argillaceous limestones, more or less bioclastic and rich in quartz-

silts in decimetric beds (“microgres” of Lucas, 1942), and of laminated marls. Zoopliycos are frequent. Conglomeratic beds

with quartzite blocks (up to 50 cm) are present to the south of the fault which is sealed by the fossiliferous Bathonian bed n° 36

and the associated bioclastic limestone. N° 32 to 36: fossiliferous beds. N° 32 is a crinoid-bioclastic grainstone. See Fig. 9e. I,

transgressive beds of the Deglene Dolomite colored in purple and pink by washing of the palaeosurfaces and "palaeosols"; 2,

reworked palaeozoic blocks (quartzites and schists); 3, bioclastic limestones interbeded in the Moul el Tagga Formation; 4,

Zoophycos.

Fig. 12 .— Vue schematique dtt panorama de la cole 1222 du Col du Femane. Horst occidental de Rhar Roubane (bordure

orientale du secieur de Deglene). Le debordement ("onlap") des assises du Bajocien-Baihonien sur le paleorelief

paleozoique esl particulierement bien expose.

A. Schistes el quartzites, rapportes au Devono-Dinantien. Pendage subvertical. Surface alteree et rubefiee sur plusieurs metres

d'epaisseur.B. Dolomie dinantienne. C, "Formation de la Dolomie de Deglene" ; Aalenien-Bajocien inferieur. Les dolomies

(oodolosparites) sont derivees de grainstones et de packstones oolithiques. Elies presentent des chenaux dans lesquels sont

dissemines des blocs decimetriques de quartzites paleozoi'ques. La partie inferieure est coloree en rose-violace par suite du

lessivage des paleosols developpes d la surface du Paleozoique (n° I). Elies presentent des traces de diagene.se vadose et des

ciments en menisque; lateralement (vers le Sud entre Sidi Yacoub et la cote 1222), elles montrent des structures fenestrees

(birdeyes). des oncolithes et des laminations alga ires passant d des breches de dessiccation. L'influence des pentes est marquee

par des eboulis gravitaires (grands galets de carbonate et de quartzite). D. formation des "Calcaires microgreseux du Moul el

Tagga" ; Bathonien inferieur. Calcaires argileux, finement bioclastiques. plus ou moins charges en silts ("microgres" de

LUCAS, 1942), alternant avec des monies feuilletees. Zoophycos abondants. N° 32 d 36 : niveaux fossiliferes. L‘ensemble

s’organise en lithoclines stratodecroissantes. Des passees de conglomerats d blocs de quartzite atteignant 50 cm se

developpent au Sud de la faille qui est cicatrisee par le niveau fossilifere n° 36 et le calcaire bioclastique qui lui est associe. Le

niveau n°32 est un calcaire bioclastique (grainstone). Le dispositif transgressif esl illustre sur la photographie de la Fig. 9e. I,

niveaux transgressifs de la Dolomie de Deglene. colores en rose-violace par lessivage des paleosols. 2. blocs de quartzites et

parfois de schistes paleozoi'ques ; 3. calcaires bioclastiques intercales dans la Formation de Moul el Tagga ; 4, Zoophycos.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

171

The Tisseddoura sector

In the East (eastern horst or Tisseddoflra sector; Figs 9f, 13a), environmental evolution was different

until the Bathonian. Open sea conditions began during the early Domerian with the bioclastic

Tisseddoura Limestones containing some Protogrammoceras celebratum (d’Orbigny), P. isseli Fucini

(involute type) and Fuciniceras sp. These followed an initial Hooding indicated by the tidal Carixian

Zailou Limestones preserved only in the lower parts of the palaeoreliefs. The rates of subsidence and of

sedimentation were very slow (LUCAS, 1942; ELMI, 1977a, 1983).

Above, the Bela'ich oncolitic Beds are highly condensed. The middle Toarcian is reduced to thin and

lenticular limestones rich in ammonites, some of these having been figured (ELMI, 1977b; ELMI &

BENSHILI, 1987; ELMI & RULLEAU, 1996). The most important level is a micrite with bioclasts and

mineralized oncolites containing beautifully preserved and large sized ammonites of the Gradata Zone,

such as the last Hildoceras (H. snoussi Elmi. 1977b: PI. 4. Fig. 3, refigured in ELMI el id., 1997. Fig. 2)

Furloceras erbaense (Hauer) (ELMI & RULLEAU. 1996: PI. 9, Fig. 2) and F. evolution (Merla) (ELMI &

BENSHILI, 1987: Fie. 4), giant Osperlioceras and the first true Hammatoceras, represented by the new

species H. roubanense Elmi described below. The upper Toarcian is probably missing and the Aaleman

is only known by centimetric lags with Graphoceratids.

The Niortense Zone is also lenticular and two decimetric levels have been recognized (4 and 5 on

Fig. 15). Bed n° 4 (0 to 0.20 m) fills a channel furrowed in the Toarcian limestones; this is a micritic

limestone containing ferruginous oolites and fragments of a nearby algal mat which has been encrusted

by iron and eroded. The'top of bed 4 is truncated by an erosion surface, cutting, in peculiar, the

ammonites. The latter indicate probably the Polygyralis Subzone with Slrenoceras subfurcatum

(Schlotheim), Leptosphinctes (L.) perspicuus (Parona), L. (L.) davidsom (Buckman). L.

( Cleistosphinctes) cleistus Buckm., Cadomites deslongchampsi (Defrance), Sphaeroceras brongmarti

(Sowerby), Oppelia pouyannei (Flamand). Oecotraustes cf. westermanni Sapunov, Holcophylloceras

zignodianum (d'Orbigny) and Lytoceras endesianum (d'Orb.). Bed 5 (0 to 0.30 m) is a lenticular

representative of the Zahra Marls (laminated marly limestone). Newly recognized, it has yielded several

Spiroceras orbignyi (Baugier & Sauze) indicating the upper part ot the Niortense Zone (upper

Polygyralis and Baculata Subzones).

The Moul el Tagga Silty Limestones Formation is transgressive and tectonically discordant and has

been defined in this sector (Elmi. 1997) (Figs 14. 15). The mean thickness is ot 50 m. At the base the

formation onlaps the tilted surface of the Belaich Oncolitic Beds (Fig. 9f). The Moul el Tagga Formation

is characterized by the vertical stacking of several thinning and lining upwards rhythmic sequences ot

alternating marls and marly limestones, often silty and bearing abundant Zoophycos. In the upper part,

the sequences end with limestones containing disseminated chamositic oolites reworked Irom the nearby

seamounts (LUCAS. 1942; ELMI & BENEST. 1978). The age of the major part ot the formation is early

Bathonian as proved by scattered collections ( Morphoceras, Oraniceras). Rare and poorly preserved

Bullatimorphites could indicate the middle Bathonian. The top is marked by a major unconformity dated

of the Bremeri Zone by comparison with Deglene.

The sedimentation resumed more or less rapidly during the early Callovian (Bullatus to early Gracilis

Zones) with the beginning of the sedimentation of the Saida Clays (up to 300 m thick). The top of the

Gracilis Zone is well characterized on all the Rhar Roubane Horst by the H. (Hecticoceras) boginense

Petitclerc assemblage (ELMI. 1971a. ELMI & BENEST, 1978): H. (H.) boginense, K (H.) poster, urn

Zeiss, Collotia discus (Bourquin) and Dolikephalites gracilis (Spath). Laterally (Beni Yabir), this

assemblage includes also: Indosphinctes gr. patina (Neumayr). R. (Rehmanma) spp.. Hecticoceras

(Chanasia) michalskii (Lewinski), Prohecticoceras (Zieteniceras) pseudolunula Elmi. lhe

Phylloceratids are abundant (up to 30% of the assemblage) with the genera Phylloceras and

Holcophylloceras. Ptychophylloceras seems missing. The middle Callovian (Arkelli Zone) is well

documented by numerous and varied Lunuloceras. The last dated level ot the Saida Clays Formation

belongs to the early Oxfordian ( Parawedekindia spp.). It is a thick marly bed (15 m) and it coincids with

an inversion from a deepening-transgressive evolution to a shallowing-regressive episode. Upwai ,

several breccias mark the beginning of the relative sea-level tall. This area, from Djebel Selib (neai Horn

172

SERGE ELMl ETAL.

Fig. 13.— Details of some Jurassic outcrops of Western Algeria.

a Reduced Toarcian-Bajocian beds on top of the Tisseddoura Cliff illustrated on Fig. 9f. 1: decimetnc marly level with

Hildoceras sublevisoni Fucini (Sublevisoni Subzone, Bifrons Zone). 2: Hildoceras snoussi Elmi bed (Gemma Subzone, Gradata

Zone) 3- Hammatoceras roubanense Elmi nov. sp. bed (Alticarinatus Subzone, Gradata Zone). 1-3 = Belaich oncolitic Beds. 4:

lenticular bed of the upper Bajocian (basal Niortense Zone). Ii is a micrite containing dispersed ferruginous black and green

oolites washed from a nearby seamoum and reworked red snuff-boxes resulting from the erosion of a ferruginous algal mat. At

the top, it is truncated by an erosion surface which cut the ammonites and the snuff-boxes. 5: base of the Moul el Tagga

Formation. Locality: see Fig. 9f. Coll. Elmi, 73B29.

b Megalodontids limestones (large lamellibranch facies) of the Zailou Formation. Lower Pliensbachian (Carixian) El Menzal,

road C.W. 106 between Khemis (Beni Snouss) and El Fahs, East Rhar Roubane Mountains (Tlemcen W.). Coll. Elml

93DZ610.

c Contact between the top of the Pseudonodular limestones (2-13) and the base of the Beni Bahdel Ferruginous Limestones (2-

14) Embankment of the road C.W. 46 along the Koudiat el Haifa Hill. Beni Bahdel. Coll. Ei.ml 73BII. Bed 2-13 is dated ot

the Solare Subzone of the upper Domerian Emaciatum Zone. Vertically embedded Pleuroceras sokire (Phillips) (1) and

abundant belemnites. Rich microfauna: lnvolutina liassica Jones, Lenticulina sp., Ophtalmidium sp. (= "Vidalinamartana ),

Nodosariids, Epistominiids. Hexactinellids. Ophiurids, algae. Bioeroded surface. The rounded "block (2) on the right is not a

reworked pebble but an irregularity of the surface. The whole is capped by a laminated ferruginous crust. This probable algal

mat indicates a shallowing that occurred between the Domerian and the Toarcian. It results from a tectonic decoupling between

the shoals and the umbilics. Bed 2-14 is dated to the Levisoni Zone by several Hildaites. It marks the resumption of the

sedimentation after a gap ranging from the Elisa Subzone (topmost Domerian) to the Polymorphum Zone (lowermost

Toarcian). It can be interpreted as a sedimentologic “first flooding" and as a condensed bed in sequence-stratigraphy

nomenclature (the actual maximum of deepening occurred later during the Sublevisoni Zone marls (local maximum

"flooding”).

d e Algal mat coating the bioeroded surface of the Beni Bahdel ferruginous Limestones (lower Aaleman). The surface

corresponds probably to the washing of a soft ground and to its superficial lithification. Boring bivalves settled afterwards

(clear perforations on fig. 13e) they can be deformed by compaction. The algal mat coated the irregular surfaces, during a

shallowing episode followed by a relative sea level rise. Lower to upper Aalenian ammonites and belemnites are embedded in

the micritic infilling preserved in the dips of the irregular surface. The Tleta Limestones are missing in this area. The surface is

sealed by the Bositra marls (Zahra Marls Formation) (1) of the upper Bajocian (Niortense Zone). Gully at the foot of the

southern wall of the Beni Bahdel Dam (Tlemcen W.). Coll. Elmi, 81DZ133 and 104.

f Bou Lehrfad Reefs at the base of the Tifkirt Formation. The general shape of the reefs explains the arabian name ot the

mountain (lefrad = thigh or mutton-leg). On the right (North East) (1): Reef R3 (in Almeras et al, 1994). Reef R2 is situated at

the foot of the slope on the left (2). Strong dipping to the NW. On the foreground, the Alfa steppe hides the marls and

sandstones of the Teniet el Klakh Formation. Upper Bajocian. Niortense Zone. Djebel Bou Lerfahd and Ain Rhezala depression

near Ain Ouarka, Saharian Atlas (Naama Wilaya). Coll. Elmi, 93DZ819.

Fig. 13 — Details de quelques affleurements jurassiques de I'Ouest algerien.

a. Niveaux reduits du Toarcien-Bajocien exposes ait sommet de la falaise du Tisseddoura (cf Fig. 9f). I : niveau marneux

decimetrique a Hildoceras sublevisoni Fucini (sous-zone a Sublevisoni, zone a Bifrons). 2 : banc a Hildoceras snoussi Elmi

(sous-zone d Gemma, zone d Gradata). 3 : banc a Hammatoceras roubanense Elmi nov. sp. (sous-zone a Alticarinatus, zone d

Gradata). 1-3 .Calcaires oncolithiques du Belaich. 4 : banc lenticulaire du Bajocien superieur (debut de la zone a Niortense).

C’est une micrite a oolitlies ferrugineuses noires et vertes, dispersees depuis les hauts-fonds voisins; elle contient des fragments

decimetriques rouges remanies d partir d'une croute oncolithique ferrugineuse. La surface d'erosion qui tronque ce niveau

recoupe les ammonites et les fragments stromatolithiques. 5 : base de la Formation de Moul el Tagga. Localite : voir Fig. 9f.

Coll. Elmi, 73B29.

b, Calcaires a "grands lamellibranches" avec des Megalodontides. Formation des Calcaires compacts de Zailou

(Pliensbachien inferieur = Carixien). El Menzal, route C.W. 106 entre le Khemis des Beni Snouss et El Fahs. Partie orientate

des Monts de Rhar Roubane (W. de Tlemcen). Coll. ELMI, 93DZ610.

c, Contact des Calcaires pseudonoduleux (2-13) et des Calcaires ferrugineux des Beni Bahdel (2-14). Talus de la route C.W.

46, en bordure de la Koudiat el Haifa, Beni Bahdel. Coll. Elmi, 73B11. Banc 2-13 ; sous-zone a Solare, zone a Emaciatum.

Domerien superieur. Pleuroceras solare (Phillips) en position verticale (1) et nombreuses belemnites. Riche microfaune :

lnvolutina liassica Jones, Lenticulina sp., Ophtalmidium sp. (= "Vidalina martana"), Nodosariides. Epistominiides,

Hexactinellides, Ophiurides, algues. La surface superieure du banc est bioerodee : le "bloc" arrondi (2) n’est pas un galet

mais une apophyse des irregularites de la surface. L'ensemble est reconvert par une croute ferrugineuse laminee. II s'agit

vraisemblablement d'un tapis algaire indiquant une diminution de la profondeur entre le Domerien et le Toarcien. Ces

observations conftrment Pexistence d’un decouplage tectonique entre les seuils et les hauts-fonds d’une part, et les ombilics et

les bassins d'autre part. Banc 2-14 : Zone a Levisoni (plusieurs Hildaites). II marque la reprise de sedimentation apres une

lacune qui s’etend depuis la sous-zone a Elisa (fin du Domerien) jusqu'a la zone d Polymorphum. Ce banc peut etre considere

comme indiquant une "inondation initiale" au sens sedimentologique et comme un "niveau condense" en terminologie

sequentielle ; I’approfondissement reel intervient plus tard avec les marnes de la sous-zone a Sublevisoni qui indiquent un

maximum local d’inondation.

d. e. Surface superieure des Calcaires ferrugineux des Beni Bahdel (Aalenien inferieur). II s'agit d’une surface bioerodee

revetue par un tapis algaire qui suit les irregularites du relief apres que ce dernier a ete perfore par des bivalves (perforations

nettes sur la Fig. 13e) consecutivement a sa lithification. La baisse du niveau marin relatif ainsi enregistree a ete suivie par un

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

173

tl IU OIlf ULt tJI I CLI/H ‘tin .vu ..v^ .. . ^ , ■ _ , — 1 r\A

Ravin an pied de la partie meridionale du barrage des Beni Bahdel (W. de Tlemcen). Coll. ELMI. 81DZ133 el 104.

f Les recifs du Djebel Bou Lehrfad d la base de la Formation du Tijkirt. Leur forme generate est a I’origine du nom de la

local it e (lefrad = gigot). A droite (NE) (!) : recif R3 fin Alm Eras et al. 1994). Le recif R2 2)se trouveau pied des reliefs a

gauche (SW). L'ensemble presente un fort pendage vers le NW. Au premier plan, la steppe d Alfa s etendsur les marries ete

S gres de la Formation duTeniet el Klakh. Bajocien superieur. zone a Niortense. Djebel Bou Lerfahd et depression d Am

Rhezala pres d'Ain Ouarlca. Atlas saharien (Wilaya de Naama). Coll. ELMI, 93DZ819

Source.

174

SERGE ELMI ET AL.

50 m

LOWER

CALLOVIAN ^

-J

p-J

Sole casts

Dolikephalites gracilis (SPATH)

Parachoffatia fanata (OPPEL)

Base of the

SAIDA CLAYS Fm

111,1 Q

MOUL EL TAGGA

SILTY LIMESTONES Fm

(main part)

Oraniceras sp.

Fig. 14.— Type section of the Moul el Tagga Silty Limestones

Formation (main part); lower to middle Bathonian ("Calcaires

microgreseux") (Lucas, 1942, ELMI, 1971a, 1977a), along the

track of Djorf Tisseddoura near Sidi Yahia ou Djabert. A and

B: calcareous markers. They illustrate the onlap of marly

limestones in small incisions hollowed by bottom currents

probably due to distal storm currents. HCS: hummocky cross¬

stratifications.

Fig. 14.— Coupe type des Calcaires microgreseux du Moul el Tagga

(Bathonien inferieur et moyen). levee le long de la piste du

Djorf Tisseddoura pres de Sidi Yahia ou Djabert (ou Sidi

Yahia Oujbar in LUCAS. 1942; Elmi. 1971a, 1977a). A et B :

faisceaux de bancs plus calcaires montrant bien les

remplissages en onlap (debordement) de petites incisions

creusees par des courants de fond lies a des courants de

tempete ties distaux. HCS : stratifications mamelonnees.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

175

Fig. 15.— The progressive onlaps of the middle Lias lo lower Bathonian on the palaeorehef ol Djort Tisseddoura. 1 . Palaeozoic

basement (rubefied schists and quartzites): 2. Tisseddoura Formation (lower Domerian. Ce ebratum Zone); 3. loarcian

Belaich Oncolitic beds; 4. 5. upper Bajocian (Niortense Zone); Moul el Tagga Formation (lower Bathomen) thin marly

bed (5) overlying the eroded surface of 4. A and B: same calcareous markers that on Fig. 14; 6. Moul el lagga

Formation (lower Bathonian).

Fig. 15 — Ennoyage et debordement progresses du paleorelief du Djorf Tisseddoura du Lias moyen jusqu an Bathonien

inferieur ; 1 Socle paleozoi'que (schistes rubefies el quartzites): 2. Formation du Tisseddoura (Domenen tnfeneur,

-one a Celebration): 3. Calcaires oncolithiques du Belaich : 4. 5. Bajocien superior (zone a Ntortense) avec un mine e

Usere marneux (5) reposant sur la surface erodee de 4. A et B : niveaux calcaires. reperes votrfig. 14 ; 6, formation au

Moul el Tagga (Bathonien inferieur).

176

SF.RGE ELMI ETAL.

Tisseddoura) to Deglene can be choosen as a reference -area for the Selib Group or Middle Sandy-

Argillaceous Group.

The Beni Bahdel Subbasin

To the east of Rhar Roubane, is another complex but small unit developed along the Tafna N030°

fault. It includes a transitional zone to the Rhar Roubane shoal with a moderately deep and narrow area

(Koudiat el Haifa Zone) and a deeper area (Tleta Zone).

Above shallow carbonates, attributed to the upper Sinemurian (?) to Carixian Zai'lou Limestones,

with Megalodontids Limestones (Fig. 13b), there occur outer platform (Tisseddoura Limestones) and

slope (Pseudonodular Limestones) deposits of the Domerian (ATROPS et al. 1970; ELM! et al., 1974).

The Pliensbachian-Toarcian boundary is marked by an unconformity emphasized by ferruginous crusts

(Fig. 13c). In the subsiding area (Tleta), at the top of palaeofaults, the Toarcian consists of a pelagic

alternance of marls and limestones, attributed to the Bayada Formation. Brachiopods and ammonites

have been recently found in these poorly fossiliferous beds. Together with the LUCAS data (1942), they

allow recognition of the Levisoni ( Hildaites sp.) and Bifrons Zones ( Frechiella sp., Porpoceras sp.). In

the neritic profiles (Koudiat el Haifa), the Toarcian is represented by the bioclastic Beni Bahdel

Limestones in which the Levisoni, Bifrons, Gradata (?), Meneghinii Zones have been proved. The

ferruginous beds of the Levisoni Zone rest directly on the belemnite bed of the lower Emaciatum Zone

(Pleuroceras solare (Phil.); the eroded surface is underlined by a ferruginous crust which encompasses

some breccia-like blocks). They are in fact due to bioerosion.

The lower part of the Tleta Limestones (with Zoophycos) is dated of the lower Aalenian (Opalinum

Zone) under a hard ground with Tmetoceras scissum (Benecke). Several spectacular condensed levels

capped by algal crusts are developed throughout the Aalenian and the lower Bajocian of the Beni Bahdel

subbasin (particularly near the southern wall of the Beni Bahdel Dam; Fig. 13d-e). The lower Bajocian

is often missing. When they exist, the Tleta Limestones end with a condensed level rich in

stephanoceratids collected and figured by ATROPS (1974): Emileia polyschides (Waagen), E.

catamorpha Buckman, Stephanoceras (St.) humphriesianum (Sowerby), St. (St.) densicostatum Atrops,

St. (Skirroceras) freycineti (Bayle), St. (Sk.) tlemceni Atrops, St. (Sk.) cf. skolex (Buckman) (condensed

Propinquans and basal Humphriesianum Zones).

The main lithostratigraphic feature is the occurrence of thick upper Bajocian Bositra bearing marls.

They have yielded a rich pyritic ammonite fauna which has given a reference for the biostratigraphic

succession of the Niortense Zone (Zahra Marls Formation). Four local associations have been defined in

the Niortense (= Subfurcatum) Zone (adapted from ELMI, 1969, 1971a):

— Teloceras and Caumontisphinctes association: nucleus of Sphaeroceras, Normannites and

Teloceras are associated with Caumontisphinctes aplous Buckman, Oppelia pouyannei Flamand,

Oecotraustes cf. westermanni Stephanov, Strigoceras cf. paronai Trauth: this horizon can be correlated

with the Banksi Subzone (Aplous horizon).

— Spiroceras orbignyi Baugier & Sauze and Oppelia pouyannei Flamand; disappearance of

Teloceras and Normannites ; persistance of rare Sphaeroceras.

— Oppelia pouyannei Flamand and Cadomites deslongchamspi Defrance association. Rare

Caumontisphinctes (C.) polygyralis Buckman. The second and third associations can together be

compared with the Polygyralis and Baculata Subzones. These marls (more than 150 m) reduce

dramatically to the highly condensed oncolitic beds of the Eastern Rhar Roubane (Tisseddoura) in 4-5

kilometers (LUCAS, 1942, 1952). This change occurs across a major palaeofault sealed only during the

early Bathonian by the Moul el Tagga Formation as already described by LUCAS (1942).

The lower part of the Moul el Tagga Formation contains abundant Zoophycos and some crushed or

pyritic ammonites: Nannolytoceras tripartitum (Raspail), Lytoceras adeloides (Kudernacht),

Partschiceras gr. viator (d'Orbigny), Morphoceras (Ebravicerasl) parvum Wetzel, M. (E.) cf. sulcatum

(Hehl) and nuclei of Parkinsonids.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

177

The Southern margin

A southern margin (“vasiere de Sebdou". adapted from LUCAS 1942, better named Tenouchfi Zone

or Umbilic) ranging from the Tenouchfi Massif to the west to Sidi Yahia ben Sefia to the east, sustained

a rapid subsidence rate. The shallow water Zai'lou Limestones are thick, with Megalodontids beds in

their upper part and a rich microfauna described by BaSSOULLET & BENEST (1976). Deep platform

conditions appeared during the early Domerian with cherty limestones (Tisseddoura Formation)

changing abruptly to the A'l'oun ben Mira Marls (ATROPS el al. , 1970) containing a rich pyritic fauna of

the Algovianum Zone; Pleuroceras occurs in the upper Domerian documenting the displacement of

these north west european ammonites along moderately deep platform along the Sahara craton and along

the palaeoreliefs and seamounts (LUCAS, 1942). The Toarcian consists of alternating marls and

limestones which are marly dominated at the base and become progressively more calcareous upwards.

These beds are attributed to the basinal Bayada Formation. The lower metres have yielded a rich pyritic

fauna of the lower Polymorphum Zone with Eodactylites spp. and Paltarpites gr. paltus Buckman-

madagascariensis (Lemoine). In the Tenouchfi Umbilic, Zoophycos are common from the middle

Toarcian (Gradata Zone) up to the Bathonian (Elmi & BENEST, 1969). In the Gradata Zone, Merlaites

gr. alticarinatus (Merla) is associated with Hammatoceras roubanense Elmi nov. sp. (= H. nov. sp.,

Elmi & Benest, 1969; Elmi et al., 1974: PI. 5. Fig. 1).

During the Aalenian and early Bajocian, the eastern and southern borders of the Tenouchfi Umbilic

sustained strong carbonate allodapic inputs with, in the same time, a deepening of the trough. The upper

Bajocian is represented by thick marls (Zahra Marls Formation), containing abundant pyritic ammonites

(Niortense Zone, Polygyralis and Baculata Subzones): Strenoceras gr. subfurcatum (Zieten),

Caumontisphinctes (Infraparkinsonia) sp., Leptosphinctes cf. perspicuus (Parona), Cadomites gr.

deslongchampsi (d'Orbigny), Strigoceras truellei (d'Orbigny), Oppelia pouyannei Flamand,

Oecotraustes cf. westermanni Stephanov, Spiroceras spp. associated with rare specimens of the isolated

coral Montlivaltia.

The areas of thick sedimentation surrounding the Rhar Roubane have been grouped into a so-called

“vasiere Oujda-Sebdou" by LUCAS (1942, 1952) who also used the name "pretellian zone or facies” (see

also ClSZACK, 1993). This latter name is inappropriate because it can be confused with the structural and

tectonic regional nomenclature (Guardia, 1975).

The southern border of the Rhar Roubane is hidden by Recent deposits. The transition to the High

Plains can be documented slightly to the west in Morocco (southern Oujda Mountains around Tiouli). Ii

can be presumed that this transition is marked by a fringe of oolitic barriers, which provided the

reworked material known in the basin (Tenouchfi Dolomite), along the border of the High Plains

Platform (BENEST el al., 1978; MAROK, 1996). The Tenouchfi Dolomite is a Zoophycos hemipelagic

formation; its dolomitization is mainly due to a subsequent tectonically provoked recrystallization; its

age is probably comparable to the Aalenian-lower Bathonian “Dalle des Hauts Plateaux (High Plateaux

Dolomite) deposited in a tidal environment. It may also be correlated with the Deglene Dolomite which

is limited to the top and to the edge of small seamounts. But, whatever the precise and local

environment, this spreading of the carbonate production is under the control of global events which are

well known also north of the Tethys, especially on the french platform from the Lyon promontory to the

Paris Basin (ROUSSELLE & DROMART, 1996).

THE ORAN HIGH PLAINS: THE SIDI EL ABED MOUNTAINS

The Oran High Plains (or Oran Meseta, or High Plateaux) are a large subtabular steppe (covered with

“alfa” or esparto = Stipa tenacissima) with a mean elevation of 1000 m, dominated by higher mountains

to the north as well as to the south. The use of the expression Oran Meseta is here discarded because it

has often been misused (Flinch. 1996: Fig. 1, for instance), and because this region does not correspond

to a true meseta: rare outcrops of the Palaeozoic basement, occurrence of several subsiding basins or

furrows, inversion to general subsidence during the Cenozoic (tor a more complete discussion, see

MAROK. 1996).

The High Plains reach a width between 150 and 200 km. The Sidi el Abed Mountains are the only

prominent relief where the Lias-Bajocian beds outcrop. Geophysical data (MAROK. 1996) suggest that

178

SERGE ELMI ETAL.

the Sidi el Abed was a relatively subsiding WSW-ENE area, limited by basement faults and inverted

during the Atlas Orogeny.

The sedimentary and dynamic evolution from the Lias to the Bajocian (more recent Jurassic beds are

eroded) will be summarized briefly in order to indicate the new results which are of importance for

stratigraphic correlations and for palaeogeography (Fig. 16). This is the first revision of this key frontier

F 16-— Tentative correlations between the Lower Jurassic successions of the Oran High Plains and the Moroccan Hi»h

Plateaux and comparison with the Southern Border of the Figuig Atlas Domain (Algerian Southern Grouz) The

horizontal marker line has been drawn with the appearance of the mottled facies (shallow-water to sabkha deposits) of

the I oarcian (lower part of Jebel Nador Formation).

NW High Plateaux, Jebel Nador Sector. South of Debdou. From Medioni (1971).

NE High Plateaux. Beni Yala. near Guefait; from Dubar (1947) iViMedioni (1971). No recent measured field profile

has been made. Thicknesses are indicative and evaluated by comparison with Sidi el Abed.

Oran High Plains. Sidi el Abed Moutains; simplified from Marok (1996) and from unpublished field observations by

ELM! The log is a composite drawing based on field observations in the following areas, from base to top Koudiat el

Bern (KB): 1, oolitic limestones with three brachiopods beds: 2. cherty limestones; 3, bird eyes limestones. Chebiket en

Nmer, Oulad Amor Formation (OA): 1, bioclastic and oolitic limestones with large bivalves (“ Lithiolis", Cochlearites

etc.); 2 . cherty limestones with Gervilletoperna and brachiopods beds (100. 122, 125, 166. 178); 3. oolitic and oncolitic

limestones; 4, black dolomites with frequent channels; 5, Cochlearites and Megalodontids limestones beginning with a

breccia containing Palaeozoic and Liassic quartzite pebbles. Brachiopod bed at the top. Teniet Sassi: Jebel Nador

Formation (JN) and boundary with the overlying High Plateaux Dolomites.

Southern Grouz, Koudiat el Haiddoura and Hassi Diab. composite log. new data by Mekkaoui, unpublished.

p, e ?‘ 0 symbols. Formations^ Koudiat el Beia; OA. Oulad Amor: JN. Jebel Nador; HP. High Plateaux and High

(Southem S Grouz) Senane; KH ' K ° ud ' at 6 Ha,ddoura; 0M - 0u «l Mennat; OAB. Oued el Abiod; HL. Hassi Laama

Faces. !, limestones; 2, bioclastic limestones; 3, emersion markers; 4. oolitic limestones (packstones, grainstones)- 5

rhannilc-n e fn , ; 6 ' aTZ Iimest0 " cs: 7- Somites: 8. marls : 9. basalts, dolerites; 10. coarse conglomerates; 'll!

channels, 12, foresets and oblique stratifications; 13. horizontal laminations; 14, algal mats.

Fossils, a, ammonites; b. brachiopods; c Lithiotis and Cochlearites: d. Megalodontids; e, Perna s.l.; f, other bivalves- g

corals; h, Orbitopsella; l, other forammiferas; j, reefs and build-ups. 6

6 Plateaux trZlTT/ t f t s,ratl S ra P hl ^sJurasstque tnferieur des Hautes Plaines oranaises, des Hants

corrTlnfin^nffZ , ' ™ rldlona f de 1 A,las de Fi 8“ig (portie algerienne du Djebel Grouz). Les

formation du'jebZl Nador) >pUemen! calees sur 1 apparition des facies argileux barioles du Toarcien <base de la

NW des Hauls Plateaux. Jebel Nador au Sud de Debdou. D 'apres MEDIONI (1971).

ff de ;! Plateaux ' Bini Yal f pres de Guefait. Dapres Dubar (1947) in Medioni (1971). En Pabsence de leves

recents. les epaisseurs sont estimees d'apres cedes du Sidi el Abed.

M °'" X d “ S ^‘ el Abed i s J m P l W d '«pris Marok (1996) el des observations inedites de Eimi.

wmmet) 7 'T™ Syn, f e / ,c < ue des lev * s dans les secteurs suivants (de la base au

\ K f 8 KR ■' L f a,ccures oohthtques avec trots niveaux fossiliferes a brachiopodes ; 2. calcaires d

calca,res a structures fenestrees. Chebiket en Nmer. Formation des Oulad Amor (OA) : 1. calcaires

btoclasttques et oohthtques a grands bivalves ("Lithiotis", Cochlearites. etc.) ; 2. calcaires a si ex avec des bancs a

Gervilleioperna e, a brachiopodes (100. 122. 125. 166. 178, ; 3. calcaires oolithiques el oncolithiques ; 4 dolZites

Znf?7?,7s C nZl2 a ™ free!Ue , nl 3 ; 5 ’ calcalre l s “ Cochlearites et Megalodontides commencant par une breche a gatets de

FotfZfon duiXIVZ e rnm CC f Ca ' reS Tf : - i,S f e ,ermine,u P ar “» banc a brachiopodes. Teniet Sassi :

t o'mutton du Jebel Nador (JN) et passage aux Dolonues des Hauls Plateaux.

?n7d7s7eMf7^ouf IO " ne S,ratigraph ^ ue Whetique de la Koudiat el Haiddoura e, de Hassi Diab dapres des leves

des Sy of°n S ' F ' ,nna!,ons - KB - Koudiat el Beia ; OA. Oulad Amor ; JN. Jebel Nador ; HP High Plateaux and

■■ m “ " «*“»" ■■ OM - OAB. Ouedel

Facies 1. calcaires; 2. calcaires bioclastiques; 3. indices d'emersion: 4. calcaires oolithiaues (oackstnnes

ZZ!'f!° neS , : 5 ’ calca,re . s . oncohtluques; 6. calcaires a silex; 7. dolomies; 8, marries; 9. basaltes dolerites■ 10

conglomt rats gross,ers; 11. chenaux; 12. stratifications obliques; 13. laminations horizontal; 14. tapis algaires. ’

hZa!t ammoni,es . : F brachiopodes ; c. Lithiotis et Cochlearites d. Megalodontides ; e. Perna si ■ f autres

bivalves ; g. coraux ; h. Orbitopsella ; i. autresforaminiferes ; j. reefs et bioconstructions. '

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

179

SOUTHERN GROUZ

180

SERGE ELMI ETAL.

region since (he basic works of Lucas (1942, 1952). The lithostratigraphic nomenclature has been

adapted from (hat of the Moroccan High Plateaux (south of Debdou and Tendrara area; MEDIONI, 1971:

Nehnahi, 1996) and has been also compared with the north east part of this region (Beni Yala near

Guefai't, DUBAR, 1947) and with the Atlas-Sahara transition zone, where the successions are very similar

(documented by Mekkaoui -new data, see below- along the Algerian southern side of Djebel Grouz).

The oldest Mesozoic beds are clays with gypsum and evaporites, associated with two basaltic

(dolerite) flows, separated by thin (few meters) laminated tidal carbonates, which outcrop along faults.

These rocks are classically attributed to the Triassic but their upper part may range into the Hettangian.

An ostracofauna has been recently described in the lower part of the upper red beds, overlying the last

basalt flow (Crasquin-Soleau era!., 1997) in the near Oujda Mountains.

During the late Sinemurian and the Carixian, carbonate sedimentation developed: inner platform or

shallow ramp with brief incursion of the open sea (outer platform) indicated by several brachiopods

beds. The lower formation (Koudiat el Beta Formation; ca 25 m) contains a middle cherty level which

has yielded " Rhynchonella " moghrabiensis (Dubar) and Tauromenia arethusa (Di Stefano) of the upper

Sinemurian. Upwards, the Ouled Amor Formation (200 m) is the local representative of the “facies a

grands lamellibranches ( Lithiotis, Cochlearites, Protodiceras , Opisoma). A succession of five members

has been recorded: 1- lower Lithiotis oolitic limestones; 2- cherty limestones with brachiopods collected

in three successive levels; 3- oolitic and oncolitic limestones with another brachiopods level; 4-

dolomites; 5- finally, Protodiceras limestones. These beds have been wrongly attributed to the Toarcian.

In tact, the brachiopods can be referred to the lower Pliensbachian. In beds 100-125 (member 2: Fig. 16)

occur: Aulacothyris nov. sp. A, Hesperithyris termieri (Dubar) and its var. minor (so-called “terebratules

multiplies”), Lobothyris subpunctata (Davidson), Parathyridina mediterranea (Canavari) and

Gibbirhynchta curviceps (Quenstedt). In beds 166 and 178 (member 3: Fig. 16) occur Hesperithyris sp.

and H. termieri (Dubar). In member 5, small “ Protodiceras” sp. are associated to Zeilieria sestii

(Fucini) and Aulacothyris nov. sp. A. The faunas are linked to repeated deepening episodes (flooding

surfaces). Member 5 is overlain by lenticular micritic beds which have yielded very rare Domerian

ammonites (. Protogrammoceras celebration (Fucini), Amaltheus sp.) indicating a marked deepening of

the sea. These micrites are included in the top of the Oulad Amor Formation, as in the Moroccan High

Plateaux (Beni Yala; DUBAR, 1947 in MEDIONI, 1971).

The most important stratigraphic feature of the High Plains is the presence of very shallow marine to

sabkha facies of the Toarcian (Jebel Nador Formation; 50 m) which extend to the first folds of the Ksour

Mountains (Djebel Hafid and Antar). The palaeogeographic limits do not coincide with the geographic

and tectonic boundaries. Eastwards, the Jebel Nador Formation has been recorded from the Skouna well,

situated on the shore of the Chott ech Chergui (Skouna Clays and Gypsum Formation) (AUGIER, 1967;

Lucas, personal comm.).

Carbonate platform conditions reappear above with the High Plateaux Dolomites (= "Dalle des Hauts

Plateaux") consisting of more or less massive dolomites with intercalations of channelized oosparites

(total thickness unknown; exposed: ca 50 m).

THE KSOUR MOUNTAINS AND THE ATLAS DOMAIN

The Ksour Mountains are part of the folded Saharian Atlas; long and tight anticlines offer °ood

exposures of the Jurassic (BASSOULET, 1973; Mekahli. 1995, 1998). It must be stressed that the folded

iange is larger than the Atlas Jurassic trough. The main stratigraphic characteristics are:

— early installation of the initial carbonate platform, probably as early as the early Hettangian (inside

the Chemarikh Dolomites) or, even, the Rhaetian (Tiout Bridge Formation, BASSOULLET, 1971, 1973);

at the top, some episodic deepening can be documented by poorly preserved Hettangian (and possibly

lowermost Sinemurian) brachiopods and ammonites indicative of the first “maximum floodings” (or

more accurately, main deepenings);

7“ early deepening with pelagic facies appearing during the early Sinemurian (Semicostatum Zone):

in the southern Am Ouarka umbilic, BASSOULLET (1973) has shown evidence that the radiolarias

occurred as early as this age (lower member of the Ain Ouarka Pelagic Limestones); in the westernly

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

181

-A. OUARKA LST.

-CHEMARIKH DOL.

UBj-v

To?

flute casts

'V vegetal fossils

nodular limestones and

Ammonitico Rosso

A Sponge spicules

Pig 17.— Comparison of the stratigraphic profiles through the Saharian Atlas (Ksour Mountains) from the Northeastern

marginal folds to the Sahara "(South of Ben Zireg. between Bechar and Figuig). Each log is a synthesis of several

measured sections. For abbreviations of stages and zones: see tables I and 2. For the facies and fossils symbols: see tig.

16; TU. quartzose turbidites; TC. calciturbidites. Remark: the Raknet el Kahla is situated 2 km to the North hast Irom

the village of Ain Ouarka.

FlG 17 — Comparaison des series stratigraphiques le long d'un transect dans les Monts des Ksour depuis les plis marginaux

du NE jusqu'au Sahara (Coupe de Ben Zireg-Sud entre Bechar et Figuig). Chaque prof,! est la synthese de plusieurs

coupes. Abreviatiohs des etages et des zones : voir tableaux I et 2. Explication des symboles pour les facies et les

fossiles voir fig. 16 ; TU. turbidites quartzeuses ; TC. calciturbidites. Remarque : la Raknet el Kahla se suite a 2 km an

NE du village d'Ain Ouarka.

Source.

182

SERGE ELM1 ET AL.

Figuig umbilic, radiolarias seem to appear slightly later at the beginning of the late Sinemurian (ELMI,

1996c);

— basinal facies ranging up to the beginning of the late Bajocian, when quartzose turbidites were

interbedded within basinal marls (Teniet el Klakh Formation);

— quartzose sedimentation became progressively dominant during the late Bajocian; the return to

carbonate platform conditions was diachronous and emphasized by the development of built-up reefs at

the lower part of theTifkirt Formation while arabian ammonites arrived in the adjacent platforms. This

basin to platform inversion occurred during the middle part of the Niortense Zone (Bou Lerfahd near

Ain Ouarka; Djebel Sfissifa; Djebel Guettai, for instance) with the exception of the Median Shoal

(Souiga-Melah) and of the neighbouring El Harchai'a anticline where siliciclastic turbidites and/or

calciturbidites persisted until the end of the early Bathonian.

— no carbonate platform during the Late Jurassic; the area is invaded by the deltaic and prodeltaic

sediments of the Ksour Sandstones Group (BASSOULLET, 1973; CELFAUD, 1975; Elmi, 1978).

From the North to the South, the Ksour are composed of several zones characterized by their

different sedimentary and geodynamic history as documented by the comparison of the synthetic

profiles summarized on Fig. 17.

Fig. 18.— Jurassic outcrops of the Atlas Domain of South West Algeria and South East Morocco.

a. Marly ammonitico rosso. Local facies of the Melah Formation. Aalenian-lower Bajocian. Ain Beida, Eastern slope of Djebel

el Melah (Naama W.). Coll. Elmi, 89DZ158.

b. Lower surface of a turbiditic sandstone bed, bearing flute casts and ammonites (Leptosphinetes sp.). Base of the Teniet el

Klakh Formation (Niortense Zone, upper Bajocian). Same locality as Fig, 18a. Coll. Elmi, 89DZ165.

c. Onlap of the lower Sinemurian Ain Ouarka Formation (decimetric beds) on the truncated massive strata of the Chemarikh

Dolomites Formation (Hettangian). NW slope of Djebel Chemarikh, Ain Ouarka (Naama W.). Coll. Elml 75D24.

d. Raknet el Kahla Megabreccia (breche n° 5). Vertical dip. Heterometric blocks of platform carbonates are reworked into

marls of the same facies than the Teniet el Klakh Formation. One Ermoceras has been collected in these reworked elements.

The block in the foreground measures more than 1 m. These features illustrate sedimentation occurring at the toe of a scarp.

Raknet el Kahla, North East of Ain Ouarka (Naama W.). Coll. Elmi, 93DZ799.

e. Megabreccia in the Jebel Haimeur Blue Cherty Limestones Formation. Pliensbachian. Jebel Haimeur, North of Figuig

(Morocco). Coll. Elmi, 95MA1359.

f. Transgression of the Jurassic on the Saharian Palaeozoic Platform. The lower carbonates can be attributed to the

Pliensbachian. The scarp in the background has given a brachiopods fauna dating the upper Bajocian transgression over the

Northern Margin of the Western Sahara. Near Meksem Nedjoua. between Fendi and Ben Zireg (Algeria. Bechar W.). Coll.

Elmi 83DZ757.

Fig. 18.— Ajjleurements jurassiques du domaine atlasique d'Algerie du SW el du Maroc du SE.

a. Ammonitico rosso marneux, developpe localement dans la Formation du Melah. Aalenien el Bajocien inferieur. Ain Beida

stir la retombee orientale du Djebel Melah. Coll. Elmi. 89DZI58.

b. Flute casts sur la semelle du banc de gres marquant la base de la Formation du Teniet el Klakh. Les turbidites emballent des

ammonites (Leptosphinetes sp. I de la zone a Niortense (Bajocien superieur). Localite: voir Fig. 18a. Coll. Elmi, 89DZI65

c. Disposition transgressive des bancs decimetriques de la Formation d'Ai'n Ouarka (Sinemurien inferieur) sur les bancs

massifs et tronques par Terosion de la Formation des Dolomies du Chemarikh (Hettangien). Flanc NW du Djebel Chemarikh ,

Aih Ouarka (W. de Naama). Coll. Elmi, 75D24.

d. Megabreche de la Raknet et Kahla (breche n° 5). Pendage vertical. Des blocs heterometriques, presentant tin facies de

carbonate de plate-forme, sont remanies dans les marnes et des calcaires argileux de mime facies que ceux de la Formation du

Teniet el Klakh. Un Ermoceras a ete recolte dans un des blocs remanies. Le bloc situe a I'arriere plan mesure plus d’un metre ;

it s'agit d’une sedimentation de pied de petite ou d’escarpement. Raknet el Kahla au NE d'Ai'n Ouarka (W. de Naama). Coll.

Elmi. 93DZ799.

e. Megabreche de la Formation des Calcaires bleus a silex du Jebel Haimeur. Pliensbachien. Flanc SE du Jebel Haimeur au

Nord de Figuig (Maroc). Coll. Elmi, 95MA1359.

f. Transgression jurassique sur la plate-forme saharienne paleozo'ique. Les carbonates inferieurs peuvent etre attribues au

Pliensbachien. Une faune de brachiopodes du Bajocien superieur a ete recoltee sur les reliefs situes a I’arriere plan. Elle date

la transgression du Bajocien superieur sur la marge septentrionale du Sahara occidental. Pres de Meksem Nedjoua, entre

Fendi et Ben Zireg (Algerie, W. de Bechar). Coll. FLMI83DZ757.

JURASSIC OF WESTERN ALGERIA

183

S ome ,

184

SERGE ELMI ET AL.

The North East Border

This border, with the Hafid and Antar anticlines, belongs to the palaeogeographic domain of the High

Plains (see above). The basal Guettob Moulay Mohamed Carbonates (exposed ca 30 m) may be

equivalent to the Koudiat el Beia Formation (Sinemurian?). Above, Bassoullet (1968. 1973) has

recorded Orbitopsella dubari Hottinger. Planisepta compressa (Hottinger) sensu SEPTFONTAINE 1984

1985. quoted as Labyrinthina recoarensis (Cati) and abundant Palaeodasycladus mediterraneus Pia

from the Oulad Amor Formation (35 to 85 tn). These can be attributed to the lower Pliensbachian

(Canxtan) by comparison with similar beds (especially in the Middle Atlas) and by the occurrence of

Hesperithyris renierii (Catullo) var. sinuosa or minor Dubar. The Jebel Nador Formation is represented

by thick purple marls, bioclastic limestones and dolomites (60 to 120m). The Middle Jurassic shallow

carbonates (Antar Dolomites Formation) and the overlying sandstones are not accurately dated.

The Northern Transitional Slope

The Ksour Mountains are limited to the north-west by a trend of anticlines bordering directly the

High Plains (Djebel Guettai, Reha. Guetob Moulay Mohammed). The Lower Jurassic outcrops

especially at the top of the Djebel Reha.

It consists of three formations. At the base, the Guetob Moulay Mohamed Carbonates Formation has

a thickness of more than 150 m. It begins by a massive Dolomites Member changing upwards onto a

Lithiotis Limestones Member, rich in thick shelled bivalves, randomly disposed and containing corals at

several levels. They are overlain by the Gaaloul Cherty Formation (95-100 m and 95 m). It consists of

grey cherty limestones in decimetric beds separated by thin marls. The surface of the beds are locally

covered by varied bioclasts and oolites. These beds document an outer platform environment. Their top

is a rubefied hard ground bearing belemnites rostrums, indicating a condensed episode. The age range

from the Cartxian ( Tropidoceras sp., in the lower part) to the late Domerian (with Emaciaticeras sp. and

Iauwmen'ceras) at the top. The main part is dated of the middle Domerian ( Reynesoceras gr. indunense

(Meneghmi). Prodactylioceras sp.. Arieticeras sp.).

Above, the Reha Formation (150 m) is a thick cyclic sequence:

- a Item an ce marls-limestones beginning at the top of the Domerian (Tauromeniceras sp.) and

ianging onto the early Toarcian ( Paltarpites sp. and Dactylioceras (Eodactylites) gr. mirabile Fucini

indicate the lower Mirabile Subzone of the Polymorphum Zone; higher, Dactylioceras (Orthodactylites)

sp. marks probably the top of the same zone);

— marls bearing a pyritic ammonite fauna of the Bifrons Zone; the Gradata Zone is badly

documented at the top by loose ammonites: Pseudogrammoceras subregale Pinna and “ Podagrosites"

gr. aratum (Buckman) associated with Alocolytoceras dorcadis (Meneghini). These marls have been

accumulated along a slope, indicating the presence of a narrow oolitic barrier limiting the Atlas open sea

from the High Plains sabkha (CORNET el al ., 1953; BASSOULLET, 1973; MEKAHLI, 1995). Toarcian

marls containing dwarf or miniature ammonites indicate a tendancy to the isolation of the area in a

relatively deep marine environment.

This general instability can be compared to similar conditions which are known during the early-

middle Toarcian along the northern ridges of the Moroccan Central High Atlas (Talghemt Pass) or along

the faults limiting the Figuig Atlas and the Western (Higher) Sahara. This marked Toarcian deepening

led to the differenciation of umbilics along the bordering faults. The return to a platform setting was

rapid with the deposition of Zoophycos limestones, passing vertically and laterally to shallow carbonates

(Antar Dolomites Formation). During the late Bajocian. oolitic bodies and reefs prograded from the SW

and the west (Guettai Formation) over alternating marls and neritic limestones yielding the now classical

trmoceras fauna (ARKELL & LUCAS. 1953; Du DRESNAY, 1964b; ALMERAS el al., 1994; ENAY, 1996).

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

185

The Ain Ben Khelil Subbasin

This is known from wells (see Kazi-Tani, 1986; Ait-Ouali, 1991; AIT-OUALI & DELFAUD, 1995)

and Toarcian outcrops (Ras el Guenatis). The Toarcian facies (alternating marls and micritic limestones)

seems to indicate that the sea bottom was then less deep than at the top of the Reha slope. This is

consistent with the data given by the ammonites (Furloceras of the Gradata Zone which have been

previously misidentified as Bouleiceratids; Ai'T-OUALI, 1991) which have a “normal” size. The area was

not invaded by the Bajocian reefs and the deposition of siliciclastic lurbidites continued until the early

Bathonian, particularily in the famed locality of El Harchai'a (FlamAND. 1911) where the alternating

sandstones-marls is rhythmically interrupted by allodapic oolites and by bioclastic limestones (ELMl &

Almeras, 1985). rich in ammonites, brachiopods and bivalves. It is the type locality of Oraniceras

hamyanense Flamand (see also Fig. 1 lb). The abundance of Ctenostreon (= Lima) palati Flamand is

noteworthy (Bassoullet. 1973). These beds can be considered as a marginal facies of the Teniet el

Klakh Formation.

THE MELAH -SOUIGA (OR MEKALIS) MEDIAN SHOAL

The initial platform carbonates (Souiga Dolomites Formation) indicate a tidal to intertidal dominated

environment. However, their upper part is more calcareous and it yields a rich rhynchonellids fauna,

similar to that of the Ouarsenis where it has been collected below Tropidoceras (BENHAMOU, 1996). It

is associated with Zeilleria hierlazica (Oppel) which appeared only during the Sinemurian. Above,

calcareous red nodular or pseudonodular (bioturbated) limestones occur (calcareous ammomtico rosso)

at the base of the Domerian Aouinet es Siah Formation. The upper part of the formation consists of

cherty limestones. The Toarcian is represented by the marl-dominated lower part of the Ain Beida

Formation overlain by the Aalenian Zoophycos limestones (Djebel Souiga) passing into a marly

ammonitico rosso (Melah) (Fig. 18a).

The dynamic role of this region seems to have changed during the Aalenian-Bathonian: there are no

Bajocian carbonate platform nor reef. Distal turbidites occurred during the early Bathonian; they are

associated with slumps and brachiopods-rich limestones (top of the Teniet el Klakh Formation which is

younger than in the Guettai (to the north) and in the Ain Ouarka (to the south) areas). In the Ain Beida

section of Djebel Melah. the Teniet el Klah Formation begins with a turbiditic bed showing flute-casts

and containing rare ammonites (Lepiosphinctes) of the upper Bajocian (Fig. 18b). Channelized

sandstones have appeared after the early Bathonian (BENHAMOU & Elmi, unpublished). Note that the

limit between the Teniet el Klakh Formation and the Tifkirt Formation is now placed under the first

channelized sandstones instead of being defined on biostratigraphic data (BASSOULLET 1973; Elmi,

1978). The type locality of these two formations is situated across the pass separating the Djebel bouiga

and the Djebel Tifkirt.

The Ain Ouarka Subbasin or Central Umbilic

This was the most strongly subsiding area of the Ksour where the thickness of the sedimentary

accumulation depended largely on pull apart dynamics up to the late Bajocian (BASSOULLET, 1973;

MEKAHLI. 1995. 1998; MEKAHLI & ELMI, 1997). The Jurassic succession begins with the initial

platform carbonates of the Chemarikh Dolomites Formation documenting a shallow protected subtidal

environment, with indication of a reef-barrier (Ait-Ouali, 1991). Near the top, some brachiopods

including Zeilleria perforata (Piette) (= Terebratula psilonoti Quenstedt) indicate the first open sea

influences. They occur under the first occurrence of an ammonite (MEKAHLI, 1995). It is a poorly

preserved but significant specimen belonging probably to the subgenus Caloceras (Fig. 1 le) and

suggesting that a seaway has been temporarily open through the eastern Atlas Ranges. It also indicates

that'the first important Jurassic deepening took place as early as the early Hettangian.

186

SERGE ELMI ETAL.

The Chemarikh Dolomites were tilted and eroded before the onlap of the following Ain Ouarka

Pelagic Limestones. These limestones consist of pelagic micrites bearing radiolarias and Diotis. Their

deposition began during the early Sinemurian. On the north west side of Djebel Chemarikh, this

relatively thick unit (120 to 160 m) shows a succession of seven members (A to G) (Table 3).

Member A

Deep platform limestones onlapping the truncated Chemarikh Dolomites. They consist in micrites

with silty quartz, scarce bioclasts and foraminifera, including Nodosariids and Involutina liassica Jones

(BASSOULLET. 1973: 147, 431-433). an association commonly found in basinal or slope facies. The

composition of the ammonite fauna, discovered by BASSOULLET (1966, 1973) indicates that it may be

correlated with the Semicostatum Zone. This has been completed by recent field sampling: Amioceras

geometrician (Oppel), A. miserabile Fucini, A. cf .speciosum Fucini, A. cf. flavum Buckman. This fauna

may range into the Turneri Zone and globally it can be compared with the Rejectum interval, defined by

DOMMERGUES et al. (1994) in the Central Apennines and EL HARIRI et al. (1996: Fig. 15) in the High

Atlas of Beni Mellal. The Chemarikh data (Central Ain Ouarka Umbilic on Fig. 17) allow a better

definition of the biostratigraphic range of this interval (or "horizon"). It does not range up into the upper

Sinemurian since it is overlain by Asteroceras -bearing limestones.

Member B

Wavy bedded, grumelous and bioturbated limestones, irregularity coloured pink (1-3 m, disappearing

toward the north east, near the crest of the palaeorelief; Kazi-Tani, 1986; Ait-Ouali, 1991). It has

yielded a rich fauna of the Obtusum Zone with large and well preserved Asteroceras which are figured

here because of their exceptional interest, not only for the Maghreb but for all the Tethyan realm. They

bear a strong affinity with the lombardian fauna illustrated by PARONA (1896): Asteroceras stellare

(Sowerby) in PARONA (Fig. 21a), A. cf. and aff. confusion Spath (Figs 19b, 20), A. meridionale

Dommergues, Meister & Mettraux (Fig. 21b, c), A. various Parona, A. margarita Parona (which can be

slightly younger than the rest of the fauna) (Fig. 22a), Amioceras cf. arnouldi (DUMORTIER).

Epophioceras sp. (ct. E. sp. in DOMMERGUES et al., 1994: PI. 3, Fig. 1) comes from the nearby locality

of M'zimer on the South East edge of the Djebel Chemarikh. The Asteroceras beds are overlain by 5 m

of sublithographic limestones containing Gleviceras gr. dor is (Reynes) (Fig. 22b) (Oxynotum Zone).

They may rest directly on the truncated Chemarik Dolomites (Fig. 18c).

Member C

Radiolarias rich cherty limestones. Ammonites become rare but several levels of the Raricostatum

Zone are present:

— a lower level with Plesechioceras cf. delicatum (Buckman) (Fig. 22c) and badly preserved

Oxynoticeratids;

— a level with Schlotheimiids: Angulaticeras gr. dumortieri (Fucini);

— an upper level with Paltechioceras nov. sp. (showing a relatively narrow umbilicus for the genus

and straight ribbing; it is close to P. boehmi in PALLINI (1986: pl.l, fig. 2) non Hug).

Member D

Wavy bedded limestones and marls. The upper part is a coquina with thin-shelled bivalves ("Diotis”

joints Meneghini; BASSOULLET. 1973: PI. 5. Fig. 2). Small ammonites: Galaticeras cf. aegoceroides

(Gemmellaro) of the Carixian.

Member E

The marls become progressively frequent. The Demonense Zone (Carixian) is documented by the

appearance of Tropidoceras calliplocum (Gemmellaro). The late Carixian (corresponding to the Davoei

Zone) is known near the top where the Protogrammoceras appears with P. gr. dilectum-pseudodilectum

(Fucini) and P. gr. volubile-pantanelii (Fucini).

Source

F,G. 19.— Jurassic ammonites of the Rhar Roubane and Ksour Mountains (respectively Tlemcen and Naama Wilayate,

Algeria).

st.Hammatoceras roubanense Elmi nov.sp. Topotype. Same locality and bed as Fig. 11 c-d. Coll. Elmi.Univ. Lyon, n° 2 9 9 802; x I.

b. Asteroceras aff. confusum Spath. Upper Sinemurian. Obtusum Zone. Asteroceras be ds, member B of the: Am Ouarka Iforma¬

tion. NW slope of Djebel Chemarikh. Ain Ouarka near Ain Sefra. Ksour Mountains. Coll. Elmi, Umv. Lyon, n _99661 . x U.b.

Fig. 19.— Ammonites jurassiques des Monts de Rhar Roubane el des Ksour (respectivement Wilayate de Tlemcen et de Naama.

Algerie).

a. Hammatoceras roubanense Elmi nov. sp. Topotype. Meme localite et niveau que sur la Fig. llc-d. Coll. Elmi. Umv. Lyon.

n° 299802 : x 1.

b. Asteroceras aff. confusum Spath. Sinemurien superieur. zone a Obtusum. Bancs a Asteroceras membre B deja Formation

d'A'in Ouarka. Flanc NW du Djebel Chemarikh. Ain Ouarka pres d Am Sefra. Monts des Ksout. Coll. ELMI. Unix. Lyon.

n° 299661 : x 0.6.

Snurre MMHAl-Qariz-

188

SERGE ELMI ETAL.

Eig. 20. Asteroceras cl. confusion Spaih. Upper Sinemurian. Obtusum Zone. Asteroceras beds, member B of the Ain Ouarka

formation. Locality: see Fig. 19b. Coll. ELMI, Univ. Lyon, n° 299662; x 0.6.

Fig. 20.— Asteroceras cf. confusum Spaih. Sinemurien superieur. zone a Obtusum. Bancs «Asteroceras, membre B de la

Formation d Am Ouarka. Localize : voir Fig. 19b. Coll. ELMI. Univ. Lyon. n°299662 ; x 0.6.

Source: MNHN, Paris

FIG. 21.— Sinemurian ammonites of the NW slope of Djebel Chemarikh. Ain Ouarka near Ain Sefra (Ksour Mountain,

Algeria).

a, Asteroceras stellate (Sowerby) in Parana. Locality and bedisee Fig. 19b. Coll. Elmi. Univ. Lyon, n° 299664.

b, Asteroceras aff. meridionale Dommergues et al. Locality and bed: see Fig. 19b. Coll. Mekahli. Univ. Lyon, n° 299666.

c, Asteroceras aff meridionale Do rrme rgu esetal. Locality and bed: see Fig. 19b. Gill. Mekahli. Univ. Lyon, n 2 99665, x 06.

FlG. 21.— Ammonites sinemuriennes du flanc NW du Djebel Chemarikh. Ain Ouarka pres de Ain Sefra (Monts des Ksour.

Algerie).

a. Asteroceras stellare (Sowerby) in Parana. Localite et niveau : voir Fig. 19b. Coll. Elmi. Univ. Lvon. n°299664.

b. Asteroceras aff. meridionale Dommergues et al. Localite et niveau : voir Fig. 19b. Coll. MEKAHLI, Univ. Lyon, n' 299666.

c. Asteroceras aff. meridionale Dommergues et al. Localite et niveau : voir Fig. 19b. Coll. MEKAHLI, Univ. Lyon.

n°299665 ; x 0.6.

Snnrrc MMHM Paris.

190

SERGE ELMI ETAL.

Member F

Ammonitico rosso (micritic pink limestones in decimetric beds separated by thin marly layers). It

contains a rich fauna of the Celebratum and Algovianum Zones with abundant large macroconch

Reynesoceras (including Aveyroniceras).

Member G

Green marls and limestones, stacked into a upward stratodecreasing sequence. They begin in the

Algovianum Zone and the top is dated to the Emaciatum Zone. One specimen of Pleuroceras solare

(Phillips) has been collected. This is the first occurrence of this northern ammonite known at the toe of

the Saharian margin (Fig. 110- To the north-east (Raknet el Kahla), the facies changes to micritic

limestones containing several levels rich in Tauromeniceras (Elisa Subzone).

Upward, the Ain Rhezala Formation is a thick marl-dominated unit, changing to micritic limestones

at the top. All the Toarcian zones have been evidenced. The lower Gemma Subzone of the Gradata zone

is particularily fossiliferous. The succession of the first Pseudogrammoceras is well illustrated. P.

subregale Pinna and P. pinnai Rivas are abundant in the Alticarinatus Subzone (upper Gradata Zone).

On the other hand, the micritic limestones of the Aalenian and of the lower Bajocian, interrupted by

some inputs of reworked material (oolites and lenticular breccias) (Raknet el Kahla Megabreccias), have

yielded only a few ammonites: Leioceras (Cypholioceras) cf. comptum (Reinecke) (Opalinum Zone,

Bifidatum = Comptum Subzone), Staufenia (=Ancolioceras) opalinoides (Mayer) (Murchisonae Zone,

Haugi = Opalinoides Subzone), Ludwigella cf. arcitenens (Buckman) and Euaptetoceras sp. (Concavum

Zone). Calciturbidites, slumping and megabreccias become frequent.

Siliciclastic turbidites were widespread at the beginning of the Niortense Zone (upper Bajocian) and

the first sandstones mark the beginning of the Teniel el Klakh Formation which documents a

particularity high subsidence ratio (thickness up to 300 m for the lower part of the zone). A rapid and

clear shallowing occurred at the end of this zone, preceeding the progradation of the Bou Lerfahd Reefs

and Limestones within the neritic limestones, marls and sandstones of the Tifkirt Formation which

begins, here, at the top of the Niortense Zone and ranges up to the early Bathonian. This evolution

suggests a tectonic interruption of the basinal conditions leading to progradation of the carbonate and

siliciclastic platforms (final or senile homogeneization stage). This dynamic inversion from a general

deepening to a shallowing regime is interrupted by oscillatory parasequences. This inversion seems due

to a major tectonic event (ELMI, 1978) with change from the umbilic (extension) stage to the depocenter

(sag) stage; after this event the sedimentation rate kept pace with subsidence even when this latter was

enhanced by more global controls (eustacy).

Tectonically controlled slopes are evident from the existence of the Raknet el Kahla Megabreccias

which have been deposited diachronously from the early Aalenian to the early Niortense Zone. They are

transitional to the Saharian border but some are transverse to the general trend. Thus a south-western

Fig. 22.— Sinemurian ammonites of the NW slope of Djebel Chemarikh (continued).

a. Asteroceras margarita Parana. Upper Sinemurian. Obtusum Zone. Top of the Asteroceras beds. ATn Ouarka Formation

(Member B). Locality: see Fig. 19b. Coll. Elmi. Univ. Lyon. n° 299663.

b. Glevicerus gr. doris (Reynes). Upper Sinemurian. Oxynotum Zone. Ain Ouarka Formation, member B. above the

Asteroceras beds. Locality: see Fig. 19b. Coll. Mekahli, Univ. Lyon. n° 299803.

c. Plesechioceras cf. delicatum (Buckman), Upper Sinemurian. lower Raricostatum Zone. Member C, Ain Ouarka Formation.

Locality: see Fig. 19b. Coll. Bassoullet, Univ. Poitiers: x 1.

Fig. 22 .— Ammonites sinemuriennes dtt plane NW du Djebel Chemarikh (suite).

a. Asteroceras margarita Parona. Sinemurien superieur, zone a Obtusum. Sommet des bancs a Asteroceras. Formation d’A'in

Ouarka (Membre B). Localite: voir Fig. ]9b. Coll. Elmi, Univ. Lyon, n°299663.

b. Gleviceras gr. doris (Reynes). Sinemurien superieur. zone d Oxynotum. Formation d’Atn Ouarka, membre B au-dessus des

bancs a Asteroceras. Localite : voir Fig. 19b. Coll. Mekahli, Univ. Lyon, n° 299803.

c. Plesechioceras cf. delicatum (Buckman). Sinemurien superieur, partie inferieure de la zone a Raricostatum. Formation d'Ain

Ouarka, membre C. Localite: voir Fig. 19b. Coll. Bassoullet, Univ. Poitiers ; x I.

JURASSIC OF WESTERN ALGERIA

191

f'CtUTf'. ¥ Nftb'i p . anc i

192

SERGE ELM1 ETAL.

sector (Chemarikh), with thicker, deeper and more argillaceous deposits, can be separated from an

north-eastern one (Raknet el Kahla) where megabreccias are more frequent and thicker (some blocks

exceed 1 m) (Fig. 18d). These megabreccias appear here late as the underlying alternating marls and

limestones (Ain Rhezala Formation) range from the early Toarcian (Eodactylites) to the end of the early

Bajocian [Emileia cf. brocchi (Sowerby), Otoites cf. sauzei (d'Orbigny)]. The lower Toarcian is

noteworthy by the presence of a “niveau chocolat” (brown coloured) which is a thin calciturbidite.

Similar and coeval beds are known in the Middle Atlas (COLO, 1962) and in the Lusitanian Basin of

Portugal (MOUTERDE et al., 1979; Wright & Wilson, 1982; Duarte, 1994, 1996). The breccias

contain limestones (with bioclasts, corals and brachiopods) reworked from the adjacent platforms and,

also, resedimented “arabic ammonites” ( Ermoceras) known to have been restricted to the epineritic

shallow platform surrounding the northern Gondwanian Margin.

In conclusion, these data and the progradation of the Bajocian Bou Lerfahd Reefs allow us to

interpret that a polygonal tilted block was differentiated along the Djebel Chemarikh in the median part

of the Ain Ouarka Subbasin. It was rising from the SW to the NE and supporting evidence can be found

from the sedimentary perturbations shown by the Liassic formations. This block was limited by steep

slopes. The present Ain Ouarka N90 fault and Triassic outcrop underline the northern limit of this

palaeostructure.

The southern border (Kerdacha)

To the south of the Ain Ouarka umbilic, there are no outcrop of the Saharian Jurassic. The transition

is known only to the west in the Djebel Kerdacha where the Liassic to Bajocian deposits show evidence

ot shallow platform conditions. However a ditinct deepening occurred probably during the late

Pliensbachian (sponge-spicules) and the Toarcian. The Toarcian history of the Kerdacha evokes that of

the coeval ramps known in the Western Rhar Roubane (Khorchef Beds) and in the Saida Mountains

(Keskess Beds) (Elmi et al., 1985). Southward, a subsiding basin extended onto the Lower Sahara but

the environment remained always margino-littoral and sabkhai'c (see BUSSON, 1967).

THE FIGUIG ATLAS

The stratigraphy and the palaeogeographic evolution of this area located along the frontier have not

been studied during the last 20 years. An extensive study of so large a region exceeds the scope of this

paper. A partial revision and new observations have been made to complete the data necessary to a good

representation of the Atlas - Sahara transition in one of the very rare regions where it is well exposed.

The Figuig-Bou Arfa region has previously been united with the more eastern Ksour Mountains

(Saharian Atlas) (ROCH, 1950) or to the so-called Eastern High Atlas (Du DRESNAY, 1964a; EL KOCHRI

et al., 1997). It is. however, really different in its physiographic, structural and stratieraphic features.

The general trend of the Atlas range changes from W-E (to the west) to SW-NE (to the east). The

longitudinal W-E trend is also disrupted by transverse north-south trends, resulting in a network of

narrow ridges limiting small subsiding umbilics, from 10 to 15 km wide.

This structural pattern is partly inherited from the Trias-Jurassic divergent palaeostresses and

palaeomotions which have led to a rift stage (Du DRESNAY, 1975; EL KOCHRI et al, 1997) probably

complicated by a detachment fault along the Saharian border as supposed in the Central High Atlas

(Warme, 1988; WARME et al, 1988). The steepness of the transition from the Atlas trough to the

Saharian platform is well documented between the Southern (Algerian) Djebel Grouz and the slopes and

umbilics situated a few kilometers to the north along the political border. The extensional palaeostresses

shifted obliquely to the trough from WNW-ESE to NNW-SSE / N-S. It is well documented by abrupt

sedimentary and environmental changes.

The present description will deal only with the southern area corresponding to the Figuig Umbilic

(ROCH. 1950) which presents a situation similar to those of Beni-Bassia (south of Bou Dahar to the

west) and Am Ouarka (north east). The major palaeogeographic events and stratigraphic data have been

established by Du DRESNAY (1956. 1957a. b. 1958, 1964a). The Figuig umbilic is limited by the Maiz

Source: MNHN. Paris

JURASSIC OF WESTERN ALGERIA

193

ridge to the north. To the south, the transition to the Saharian Platform is exposed in the Algerian part of

the Djebel Grouz.

FlGUIG SUBBASIN OR UMBILIC

We present a preliminary revision of the previous data on the Jebel Haimeur (ROCH, 1950; Du

DRESNAY, 1963; 1964a; 1966: p. 18, fig. 73; 1988b) (Fig. 23).

Lower Dolomites

They are comparable to the Chemarikh Dolomites Formation of the Saharian Atlas. Thickness: more

than 100 m. Rare limestones containing silicified gastropods (Flettangian-lowermost Sinemurian). Du

DRESNAY & Dubar (1963) have cited a fauna coming from limestones preserved from the

dolomitization. The ammonite genus Arnioceras documents the lower Sinemurian.

“Calcaires bleus du Jebel Haimeur” Formation (= Jebel Haimeur Blue Cherty Limestones

Formation)

They were informally named by ROCH, 1950; cropping out to 75 m. They begin with onlapping grey

micrites rich in radiolarias, sponge-spicules and silt-sized quartz grains. Interbedded greenish marls

contain silts and ferruginous and carbonate particles but no microfauna. This indicates a main deepening

episode which can be compared to a maximum flooding surface in the sequence stratigraphy

nomenclature (Fig. 23). In the canyon situated at the south of the television relay station, the onlapping

beds have yielded a pyritic condensed fauna at 2.50 m above their contact with the dolomites. Rare

representants of the Obtusum Zone (“ Vermiceras ” rothpletzi in FUCINI, with a whorl section similar to

that of Epophioceras) are asociated with abundant Paltechioceras indicating the higher part of the

Raricostatum Zone. Du DRESNAY & Dubar (1963) have already established the occurrence of

Paltechioceras tardecrescens (Hauer) in the first beds of the limestones (DU DRESNAY’s outcrop 1968).

They yield a probably condensed Plesechioceras fauna (transgressive interval; stratodecreasing

parasequence). Their association indicates probably the presence of the Obtusum zone. These levels are

younger than the Arnioceras beds of the Ksour Mountains. In consequence, the main deepening (from

platform to slope-basin) occurred later in the Figuig umbilic than in the relatively close Ain Ouarka area.

Slightly North of Figuig, we have recently discovered the Asteroceras beds (A. stellare, A. aff.

confusum) at the base of the Jebel Haimeur Formation outcropping on the eastern pericline of Jebel Maiz

(near Sidi el Hadj Bahous). They are limited from the underlying Lower Dolomites by lenticular (0 to 1

m) biomicritic and oolitic limestones, yielding badly preserved Schlotheimiids and Arnioceras.

Cherty limestones and greyish (base) to greenish (top) marls occur above. The main part consists of

three parasequences of alternating marls and cherty limestones, becoming progressively carbonate-

dominated (cherty limestones). To the west, the presence of the lowermost Pliensbachian has been

supposed by Du DRESNAY & DUBAR (1963; Du DRESNAY's outcrop 2474). We have not been able to

find these levels in the eastern part of the Jebel Haimeur. Microfacies: clayey micrites with abundant

radiolarias and sponge-spicules, rare silt-size quartz grains. The marls are strongly bioturbated and

contain abundant calcareous and ferruginous particles but no foraminifera. In the uppermost 2 meters,

the cherty limestones are interbedded with intrabiomicrite (wackestones-packstones) containing

abundant reworked allodapic, badly sorted bioclasts (crinoid ossicles, echinoid radioles, brachiopods)

and oolites. Spicules-bearing intraclasts are abundant (“tuberoids”). Radiolarias remain present in the

micritic parts. These facies are coherent with an environment situated at the toe of more or less steep

slopes. They are related to the deepening of numerous Tethyan basins during the late Sinemurian

(Maghreb; Lusitanian Basin of Portugal).

Several microbreccias, conglomerates and megabreccias are spectacular, especially at the

approximate position of the limit between the Carixian and the Domerian, as indicated by the occurrence

of reworked Planisepta compressa (Hottinger). They are composed of Liassic carbonate pebbles

(centimetric to decimetric) embedded in oomicrites. Oolites as well as transported exotic corals are often

abundant in a micritic matrix. The main megabreccia (Fig. 18e) can reach a thickness of 4 m. These

features illustrate a “mass flow” resedimentation.

194

SERGE ELMI ETAL.

DYNAMIC STAGES AND

EVENTS

DIFFERENTIATION

( = SENILE

STAGE)

( = MATURE STAGE)

TEXTURE

OMBILIC STAGE

^ vcgetals (trunks)

xcr bivalves

'C) ammonites

brachiopods

echinids

bryozoans

■f Foraminifera

Rad radiolarians

Zoophycos

% madrepora

•— 'l' bioclasts

4^0 cherts

»» » main floodings

LITHOLOGY

UPPER

BAJOCIAN

DROWNING AND

PARTITIONING

CARBONATE

PLATFORM

sandstones

Maximum flooding

(or deepening) surface

W M marls

' : marls I 2 : M. mudstones ; 3 : W. wakestones ; 4 : P. packstones ; 5 : grainstones (carbonates) ;

6 : turbidites, synsedimentary breccias ; 7 : sandstones (deltaic s.L).

Fig. 23. — Log of the Jurassic of the Figuig umbilic, between Jebel el Haimeur, Teniet Oulad Amir and El Haitama.

Fig. 23— Cobnne stratigraphique du Jurassique de I’ombilic de Figuig entre le Jebel el Haimeur, le col de Teniet Oulad Amir

et les reliefs d'El Haitama.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

195

Above, the cherty limestones continue. They are made of elementary thickening-upward sequences

of marls and micrites. Cherts are abundant and correspond to the silicification of ancient burrows which

may be anastomosed in black layers. Two maximum deepening episodes (so called "maximum flooding

surfaces”) are indicated by metric levels of greenish marls during the early Domerian with two poorly

fossiliferous ammonite levels, the first with Prodactylioceras sp., the second with Protogrammoceras

celebration (d’Orbigny). Frequent reworked material (bioclasts, oolites) indicate the vicinity of slopes

(turbidites, distal tempestites). The environment was unfavourable to benthic microfauna; rare

individuals of Lenticulina and Dentalina have only been recorded. The upper thick greenish marls have

yielded foraminiferas indicating a deep platform to basinal environment: Ammodiscus siliceus

(Terquem), Lenticulina sublaevis (Franke) (mg Saracenaria), Lenticulina sp., Marginula prima

(d'Orbigny), Lingulina tenera (Bomemann), Dentalina terquemi (d'Orbigny), D. obscura (Terquem).

The last cherty limestones are dated as middle Domerian (Algovianum Zone) by Arieticeras sp. They

are composed of marly and micritic thickening-up sequences interrupted by bioclastic and ooidal

laminated beds (badly sorted packstones to grainstones with some neogenetic bipyramidal quartz)

indicating the proximity of the toe of the slope near the transition to the Sahara Platform.

The upper part of the Jebel Haimeur Formation is composed of similar cherty limestones with more

or less thick marly levels.

Near the northern border of the Figuig umbilic (Mrit-Khouabi outcrops), the Pliensbachian beds

become nodular (similar to a marly rosso ammonitico) and disturbed by spectacular slumps (Fig. 24a-b);

megabreccias and oolitic allodapic deposits are frequent as described by Du DRESNAY. Some

ammonites have been collected. Near the base, Platypleuroceras gr. brevispina (Sowerby) indicates the

Jamesoni Zone. Under the main slump, Tropidoceras sp., Reynesocoeloceras sp. and Polymorphitids

(Demonense Zone) have been collected; several Protogrammoceras sp. and “Fuciniceras” sp. indicate

the upper Celebratum zone in the ammonitico rosso outcropping on the left side of the river, at the south

of the figured outcrop. Palaeocurrent measurements have been made in the prograding redeposited

oolitic and bioclastic beds. They indicate that the transport has been multidirectional both from the south

and, mainly, from the north (from the nearby Maiz Ridge). The slumps indicate a more general

palaeoslope to the NW.

"Mantes a Hildoceratides” (Du DRESNAY, 1964a, 1975b) (20-25m).

Greenish marls with several decimetric beds of bioclastic limestones. The lower part contains

ammonites of the middle Toarcian (Bifrons Zone: Hildoceras sublevisoni Fuc., H. bifrons (Brug.), H.

angustisiphonatum Prinz, H. gr. semipolitum (Buck.); Gradatum Zone: Crassiceras gradata (Merla),

Col Unites sp.), especially on the southern size of the Jebel Maiz (near Ain Mirid) where red nodular

beds (marly rosso-ammonitico) occur. Near the top: more frequent calcareous beds with Zoophycos and

Chondrites; foraminifers are relatively diversified in the upper part (Aalensis Zone): Lenticulina

munsteri (Roemer). L. subalata, (Reuss), L. d'orbignyi (Roemer) (mg Astacolus), L. deslongchampsi

(Terquem) (mg Falsopalmula), Dentalina nodigera (Terquem & Berthelin), Ammobaculites sp. The

Hidoceratids Marls are onlapping on the underlying beds, especially to the west (Abou el Kehal. for

instance; DU DRESNAY, personal communication).

“Ouled Amir oolitic Limestones’’ (=“cretes du Dogger”, Du DRESNAY, 1964a) (5-10m).

The size of the oolites is well sorted (inframillimetric) but their shapes are irregular. They are not

contiguous despite the sparitic nature of the matrix. The structure is mainly fibro-radial and the size and

nature of the nuclei are varied. The general structure suggests that the oolites have been transported from

a nearby southern or south-eastern barrier. The Ouled Amir Formation represents the local facies of the

Dalle des Hauts Plateaux and Oued Lama Formations but in a similar palaeotopographic position to the

Tenouchfi Dolomites. The arrival of these prograding oolitic bodies indicates a shallowing which

occurred earlier than in the Ain Ouarka Basin, where, coevally, breccias accumulated at the feet ot the

bordering slopes.

Green marls (Posidonomya ornati Marls of CXJ DRESNAY. 1964a).

Outcrops of these are limited and scattered along the Oued el Hallouf Valley and at the North of the

Zenaga oasis. They can be tentatively compared to the lower Bajocian Talsinnt Marls ot the eastern

196

SERGE ELMI ETAL.

High Atlas or to the greenish marls of the turbiditic Teniet el Klakh Formation of the Ksour (base of the

upper Bajocian).

“Jebel Mellah Formation ” (Du DRESNAY, 1964a).

Shallow platform sequences of marls, bioclastic and oolitic limestones, laminated grainstones and

laminated sandstones. The foresets of the sandstones indicate a transport to the NW and to the WNW.

This observation is of prime importance as it indicates that the sand body prograded at first to the NW

and that the material has been transported to the NE only in a second phase. This must be compared with

the data obtained from the Bajocian of the Northern Ksour (near the frontier; Djebel Guettai, Forthassa;

see OUALl-MEHADJi, 1995). The quartzose arrivals began probably in the upper Bajocian but they were

mainly Bathoman with the echinid Bothriopneustes galhauseni Lambert fauna (Du Dresnay, 1964a).

hese deposits indicate that the basin had reached a “senile stage” or flexuration stage; subsidence

remained strong but it was compensed by sedimentation (depocenter stage) with a large ratio of shallow

water sihciclastics.

Fig. 24.— Shdings andl dumpings m the Pliensbachian beds in ihe middle pari of the Figuig umbilic. The pictures are

orientated from the SSE (right) to the NNW (left). Between the two main passages of the road through the Oued Mrit

(Morocco, Figuig Province). Coll. Elmi, 96MA 3-1 et 7. a. Detail of the SSE comer of the outcrop; b. General view.

F,G ■ € a stump, '! gs des couches pliensbachiennes clans la partie medicine de I'ombilic de Figuig. Orientation

S Cnl! N F,Z ‘qama'T 6 a ,\ a eS deU cci r T d r de la rou,e <0ued Mri ’> (Maroc, Province de Figuig).

Coll. Elmi. 96MA 3-1 et7.a. Detail de la partie SSE de I affleurement; b. Vue d’ ensemble. 5 *

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

197

The Figuig succession is important because it has been accumulated in a highly mobile basin

(deepening umbilic until the Toarcian) which recorded the same main Atlasic events as in the west and

in the east but the location is nearer to the slopes transitional to the platform which provided a large

amount of reworked material. The north-western direction of the palaeocurrents and slope deposits

underlines the importance of the transverse, N160 to N030, structures. It suggests that the area has

sustained conjugate stresses which may have been caused by transtensional movements. The final

change to a subsiding but shallowing platform (depocenter stage) occurred earlier than in the adjacent

areas. All these features suggest strong local tectonic control. It is here interpreted that these conditions

occurred in a kind of pull-apart structure located on the area where the general trend of the Atlas

changes.

THE TRANSITION TO THE SAHARA (KOUDIAT EL HAIDDOURA AND GUENNAFID CLIFFS ALONG THE

SOUTHERN GROUZ ATLAS MOUNTAINS)

Measured sections have been surveyed along the frontier (MEKKAOUI, BENHAMOU, MEKAHL.I,

unpublished, new data) in the southern (Algerian) side of the Jebel Grouz between Mourhal (=Moughel)

and Koudiat el Haiddoura (Fig. 17). They are briefly described here because the discovery of several

brachiopods studied by ALMERAS, indicates close similarities with the High Plateaux of eastern

Morocco and with the Oran High Plains.

The Mesozoic deposits begin with the Ben Serhane Conglomerate (thickness: 6 to 65 m) which is

transgressive and discordant on the Visean or the Precambrian. It can be tentatively attributed to the

lower Liassic (Hettangian-Sinemurian) or even to the Triassic. It extends southward to Fendi where it

has been attributed to the so-called “Permo-Trias” on geological maps without conclusive evidence.

The Koudiat el Haiddoura Formation (mean thickness: 120 m) is the local facies of the “calcaires a

grands lamellibranches” {Protodiceras, Cochlearites ). The formation begins with micritic limestones

interrupted by a synsedimentary dolomitic breccia. Upward the usual facies of shallow carbonate

platform are well developed: oolitic limestones, birds eyes, laminites (stromatolitic?). The age of these

beds has long been questionned. It is here presumed to be early Pliensbachian; regionally, their upward

limit cannot exceed the earliest Domerian (base of the Celebratum Zone). This is consistent with the

new data collected in the Oran High Plains (see above).

The late Pliensbachian (Domerian) is represented by the bioclastic limestones of the Oued Mennat

Formation (25 m) which are dated here for the first time by brachiopods ( Liospiriferina praerostrata

(Flamand) and Zeilleria sarthacensis (d'Orbigny)). Some small corals build-ups occur. Oolites and

oncolites appear in the upper part of the formation, which is capped by a hard-ground.

The overlying Oued el Abiod Formation (50 m) begins with red silty or sandy clays, changing

upward to stromatolitic laminated dolomites and to evaporitic (gypsum) marls. This formation can be

attributed to the Toarcian and it is equivalent to the Jebel Nador Formation of the Moroccan High

Plateaux and the Algerian Sidi el Abed. These new correlations are of great geodynamic value because

they indicate that the southern borders of the Atlasic furrows sustained a relative uplift during the

Toarcian while a major deepening occurred coevally in the basins and in the umbilics.

The overlying limestones and dolomites (30 m) (Hassi Laama Formation) have yielded some

brachiopods (Burmirhynchia termierae Rousselle dated as Humphriesianum to Niortense Zones). These

beds can be compared with the “Dalle des Hauts Plateaux" (Aalenian-early Bajocian). The limestones

are bioclastic and oolitic.

Southward, the Toarcian evaporitic beds are known south of the Ben Zireg Shoal in the Fendi area

where the Dogger carbonates have recorded a marked deepening and flooding episode. Jurassic rocks

disappear rapidly to the south, on the Sahara Platform (Figs 17, 180-

198

SERGE ELMI ETAL.

TRARAS

.z:

10 20 30 40km

Source : MNHN, Paris

JURASSIC OF WESTERN ALGERIA

199

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Fig. 25.— Changes in facies and in thicknesses of the Lower and Middle Jurassic deposits along a North-South transect from

the Mediterranean (Traras Mountains) to the Sahara. Key for colours and symbols: see Tables 3 and 4. TU: sihciclastic

turbidites; TC: calciturbidites.

F/G 25 — Variations des facies el des epaisseurs des depots du Jurassique inferieur el moyen le long d’un transect Nord-Sud

de la Mediterranee (Monts des Traras) au Sahara. Explication des couleurs el des figures : voir Tableaux 3 et 4. TU :

turbidites silicoclastiques. TC : calciturbidites.

Source: MNHN, Paris

200

SERGE ELMI ETAL.

THE MAIN PALAEOGEOGRAPHIC AND PALAEOSTRUCTURAL EVENTS

Chronology and event stratigraphy

A general diagram of the variations in thicknesses and facies is given on Fig. 25 along a NW-SE

transect from the Traras, near the Mediterranean Sea, to the Sahara margin, along the Algerian side of

the border.

In western Algeria, the Jurassic history of the Alpine Foreland can be summarized as a great

sedimentary (transgressive-regressive) cycle from the early partitioning between shoals and basins

differentiated along the Northern Gondwana margin until the final extension of the late carbonate

platform and of the atlasic delta. The succession of the different stages has been clearly described and

accurately dated.

The early development of the initial carbonate platform occurs from the Rhaetian to the early

Hettangian in the future troughs. The first arrival of rare ammonites happened during the late Planorbis

Zone in the most subsident area. This is the first occurrence of an ammonite in the Atlasic NW Maghreb.

Several citations of Hettangian ammonites in the old papers have not been confirmed in the Atlas

Domain. This discovery suggests that a seaway was temporarily open to the NE through the Eastern

Atlas Ranges. It also indicates that the first important Jurassic opening took place as early as the early

Hettangian and that it was linked with the westward progression of the Tethys. As Hettangian

ammonites are known in the Rif (GRIFFON & MOUTERDE, 1964) and in the Kabylia (MOUTERDE et al.,

1998), it may be supposed that there were two main seaways opening from the east to the west. The

southern one has been stopped by the Tamlelt shoal which limits the eastern High Atlas from the Figuig

Atlas.

As the Chemarikh Dolomites are eroded before the Semicostatum Zone deepening (early

Sinemurian), it seems that a major relative sea level fall occurred at the end of the Hettangian or at the

beginning of the Sinemurian.

Several levels yield poorly preserved brachiopods which may indicate short and badly documented

sea-level rises during the rest of the Hettangian.

The pre-Semicostatum unconformity resulted probably from several and telescoped changes in

relative sea level, some of them related to local tectonic stresses.

During the Semicostatum and Tumeri Zones (early Sinemurian), a deepening-transgressive episode

occurred in the differentiating Atlasic umbilics. The deepening continued during the late Sinemurian in

the subsiding axes (furrows and umbilics), associated with poorly dated local transgressions. In the

intermediate zones between troughs and platforms, the initial carbonates are capped by brachiopods-

bearing limestones indicating a late Sinemurian event, which is, until now badly dated. These late

Sinemurian events are better documented in the Moroccan High Atlas by the widespread occurrence of

the Plesechioceras fauna (Du DRESNAY & DUBAR, 1963; see also DUBAR, 1962).

A major transgression occurred during the earliest Pliensbachian (early Carixian-Demonense event)

as the result ot a regionaly enhanced general sea level-rise. Ammonites arrived in previously flooded

regions coevally with the transgression of shallow carbonate platforms on continent or sabkhas. During

this deepening-flooding episode, the marker facies of thick shelled bivalves limestones (so called

“Lithiotis and Megalodontids limestones” or “calcaires a grands lamellibranches”) was at its climax.

This fauna is well known in the Maghreb where it has been cited for the first time by Dubar (1932). It

has been attributed to the Domerian (Dubar, 1948) and the majority of the following authors have

considered that it would be marker of this “substage”. However, in the Bou Dahar, some of these

bioaccumulations are mterbedded in middle Carixian limestones. A fragment of Tropidoceras has been

sampled in this situation near Ksar Moghal (east part of Bou Dahar, AMHOUD et al., 1997) In the same

area (Kheneg-Grou), Dubar & MOUTERDE (1978, locality 15) have quoted the occurrence of T. cf.

Source: MNHN, Paris

JURASSIC OF WESTERN ALGERIA

201

calliplocum (Gemmellaro) in pink limestones deposited at the foot of the eastern slope of the reef (Du

DRESNAY, pers. comm.)- These beds range from the Ibex zone up to the early Domerian (Celebratum

zone). Slightly North of Kheneg Grou, Dubar & MOUTERDE (1978, locality 18) have also quoted a rich

fauna of the Ibex Zone in similar pink limestones which are transitional to the basin and equivalent to

the Megalodontids limestones.

Renewed deepening occurred near the end of the early Domerian (final Celebratum Subzone of the

Celebratum Zone).

During the Elisa Subzone (latest Domerian) and Polymorphum Zone (earliest Toarcian) telescoped,

opposed or enhanced local and global events led to an exaggeration of the differences between shoals,

slopes and basins. The result was a large range of reduced to thick beds and a wide distribution of slope

deposits and fissures (Sekika; Bou Dahar, DUBAR, 1950).

A peak of deepening occurred during the end of the early Toarcian and the beginning of the middle

Toarcian (Levisoni Zone and, mainly, Sublevisoni Subzone; see legend of Fig. 13c) but it did not

coincid everywhere with real transgression because of local tectonic uplift. The bottom of the umbilics

was deepening in the meantime whereas the borders remained stable or, even, emergent. Subsequently,

shallowing-up and filling-up sequences followed. The Gemma Subzone event occurred as a condensed

bed indicating a relative deepening. A clear regressive trend appeared near the end of the Toarcian (pre-

Meneghinii unconformity). It is documented by the inversion to carbonate dominated sediment

production.

Condensed beds were frequent during the Opalinum Zone (early Aalenian). They document both a

global transgressive regime and a global change in sediment production. Hard-grounds, erosion surfaces,

rapid vertical changes from shallow stromatolitic beds (Fig. 13d-e) to relatively deep ammonites-rich,

ferruginous or phosphatic layers and to Zoophycos hemipelagic limestones are spectacular, especially in

the Tlemcen Domain and along the borders of the Atlas.

This highly perturbed regime continued until the end of the early Bajocian. The consequences differ

greatly from an area to an another. The climax of these perturbations appears to have happened through

The Aalenian-Bajocian boundary, but continued until the late Bajocian in some areas (Rhar Roubane

horst for instance) or even later (to the end of the Bathonian on the shoals of the Traras Mountains). In

the basins of Western Algeria, a strong deepening occurred at the beginning of the late Bajocian

(Niortense Zone) with the accumulation of thick marls (Zahra Marls Formation) in the Tlemcen

Domain. These are interbedded with siliciclastic turbidites in the Ksour (Teniet el Klakh Formation). In

the deep and narrow umbilics of the Traras, the deepening happened earlier (early Bajocian), with

calcareous turbidites (Fenakech Formation) and marls (Ain Killoun Formation) . During the late

Bajocian, the Saharian Atlas (Ksour) sustained a decoupling between the shallowing borders

(progradation of the reef) and the still deepening umbilics. In the meantime, the Moroccan Atlas had

reached their “senile” stage with shallowing depocentres succeeding the deepening umbilics (Jebel

Mellah Formation of the Figuig Atlas, for instance). In the High and Middle Atlas, these events are

diachronous by comparison with the Ksour. A peak deepening is obvious during the Humphriesianum

Zone, following a Sauzei Zone unconformity indicated by condensation, erosion and reworking

(Benshili, 1989; Fedan, 1989; Sadki, 1996).

Transgression and deepening resumed in the north during the early Bathonian: hemipelagic marls and

limestones, often silty, accumulated in the basins (Moul el Tagga Formation of Rhar Roubane; Sekika

Marls of the Traras) changing laterally to ferruginous oolitic limestones (Deglene Oolitic Ironstone) or

to condensed beds.

The middle Bathonian was a time of general shallowing illustrated either by thick neritic

accumulations interbedded with prograding sandstones (Tifkirt Formation) of the Ksour, or by

ferruginous limestones (top of the Deglene Oolitic Ironstone).

A general sedimentary gap of the upper Bathonian is well documented in the Tlemcen Domain

(ELMI, 1971a, b). Sedimentation resumed diachronously during the early Callovian (Bullatus and

Gracilis Zones). The numerous shallowing turbiditic sequences of the Saida Clays Formation are.

however, stacked in a general deepening evolution leading to the last deepening peak which took place

during the early Oxfordian (Parawedekindia level). After, sea-depth diminished abruptly and the

Tlemcen area was invaded by the prograding cross-bedded and channelizing sandstones ol the

202

SERGE ELMI ETAL.

Boumedine Sandstones Formation ranging from the Oxfordian to the lower Kimmeridgian (BENEST

1985).

Palaeostructural and dynamic evolution (Fig. 26)

At the end of Triassic times, and probably at the beginning of the Hettangian. North Africa was

occupied by lands and by large sabkhas, extending far south to the Lower Sahara. Magmatic events

occurred, related to the first abortive rifting which is known all around the future Central Atlantic. The

palaeostructural evolution was largely controlled by a tectonic network inherited from the Variscan

events, as stated by Du Dresnay (1963, 1975, 1988a) who compared the High Atlas during the Early

Jurassic to the present day Red Sea.

MOROCCAN BLOCK ORAN BLOCK

MEDITERRANEAN SEA

ALGIERS BLOCK

PELAGIAN BLOCK

saLc.ar.eous Kabylo-Rilan ridge

Fig. 26.— General sketch of the major structural units of Northwestern Maghreb. Abbreviations: SR= Sudrifan ridges; MMA=

Middle Atlas; PA= Preatlasic sector. East of Tiaret; CONST= Constantine.

Fig. 26.— Schema des principals unites structural du nord-ouest du Maghreb. Abreviations : SR = Rides sudrifaines ; MMA

= Moyen Atlas ; PA = domaine preatlasique a I'Est de Tiaret; CONST = Constantine.

During the Hettangian-earliest Sinemurian the future Atlas troughs were flooded by a shallow marine

transgression. This is the first expansion of the initial carbonate platform. Rare ammonites occur at the

top of the lower Hettangian (Johnstoni Subzone of the Planorbis Zone) in the Saharian Atlas, indicatin'’

that an open seaway existed briefly to the ENE. probably through the Tunisian trough. The Oran High

Plains, and the Tlemcen Domain were covered by large sabkhas, inherited from the Trias and changing

through time into more or less isolated lagoons.

Near the end of the early Sinemurian (Semicostatum Zone), the weakest parts of the Atlas troughs

began subsidence and deepening. This is especially well documented in the Figuig Eastern High Atlas

and in the Saharian Atlas (Chemarikh) where Semicostatum Zone micrites of the Ain Ouarka Formation

onlap the eroded carbonates of the Chemarikh Dolomite (Fig. 18c). This extensional regime continued

during the late Sinemurian, resulting in a clear differentiation between relatively deep basins

(hemipelagic to pelagic), slopes and shoals within the Atlas Domain. Radiolarias may be frequent in the

Am Ouarka and Jebel Haimeur Formations. The Atlas Domain was divided into numerous small and

Source:

JURASSIC OF WESTERN ALGERIA

203

often rhombic basins, whose differentiation depended on extensional and transtensional tectonic stresses

(beginning of the mosaic stage). This is the local expression of the Me Kenzie’s rift stage.

A general sea-level-rise at the end of the Sinemurian and during the early Carixian (pre-Demonense)

resulted in a transgression of regional scale and in the establishment of the initial carbonate platform in

previously emergent or sabkha areas (Oran High Plains, margins of the Atlas troughs, some intra-Tellian

shoals such as the Ouarsenis). In the Atlas umbilics (Ain Ouarka, Figuig), pelagic sedimentation

continued and coarse synsedimentary breccias were deposited at the toe of the scarps (Figuig). Thus, a

strong dynamic and environmental decoupling is evident between the Atlas domain and the northern

sectors. The beginning of the mosaic episode is often marked by the development of megabreccias and

ammonitico rosso facies along the margins (Figuig and Ksour Mountains) where slumping, reworking

and calcareous turbidites are widespread (Central High Atlas; Figuig; see also Du DRESNAY, 1988a).

Reefs (bioaccumulations and bioconstructions) are widespread along the furrows borders in Morocco

(DUBAR, 1962; Du DRESNAY, 1977, 1988b). They are less spectacular in western Algeria. During the

early Domerian (Celebratum Zone), partitioning reached the northern areas (Tlemcen and Tell

Domains). Coevally a large transgression occurred. Even the High Plains were locally invaded by the

open sea (Sidi el Abed, Beni Yala).

These episodes can be related to a detachment fault dynamic as stated in the High Atlas (WARME et

al., 1988). The main detachment may be situated in the evaporitic levels of the Triassic since

BELLHACENE et al., (1997) stated that the main South Atlas fault zone does not affect the Palaeozoic

(see also VlALLY et at, 1994).

Durino the Toarcian, the mosaic episode extended and resulted in a divided pattern of subsiding and

deepening umbilics separated by a structurally controlled network of shoals and ridges. A first

deepening peak occurred during the early Toarcian but the uplift of some large blocks (Oran High

Plains Tleta “zone” of the Beni-Bahdel (Fig. 13c); southern Saharian borders of the Atlas) indicates that

tectonic controls had become stronger. Sabkhas isolated by oolitic barriers developed on the High Plains

and on the Lower Sahara. Elsewhere, thick marly sediments accumulated in the umbilics and narrow

furrows The slopes were characterized by mass-flows, calcareous turbidites and ammonitico rosso.

Siliciclastic turbidites are known in the Traras (Polymorphum Zone of Mellala near Ain Killoun;

unpublished). This tectonically controlled event is now recognized all around the High Atlas. Ihus, a

new interpretation (SOUHEL, 1996) of the succession of the Beni Mellal borders and shoals (western end

of the Central High Atlas) indicates a similar evolution with strong local tectonic control. The turbiditic

Toarcian episodes (Brechubler. 1984) of the Moroccan central High Atlas (Talghemt; Levisom to

Gradata Zones) have been restudied (BOUTAKIOUT & Elmi, data unpublished) and correlated with the

slope deposits of .he Saharian Atlas (Hassi Ben Khelil Umbilic) All these reworked deposits are located

in a comparable structural and palaeogeographical setting at the toe of the slopes bordering the High

Plains, High Plateaux and High Moulouya shoals and ridges. Differential movement between the

subsiding umbilics and their rising borders is striking and highly significative ot local tectonic controls.

The Traras Mountains give a good model for this (Mellala and Sidi Boudjenane, see part The lemcen

Domain", Fig. 10).

Some of the largest shoals or shallow outer platforms developed neritic conditions, similar to those in

NW Europe (borders of the French Massif Central) with the deposition of oolitic or bioclastic ironstones

(ferruginous platforms; Middle Atlas, Western Rhar Roubane, some shoals of the Tunisian Ridge).

Synsedimentary compression has been locally documented in peculiar in the Traras Mountain where

a gentle folding of the Pliensbachian limestones has been described It occurred before the erosion of the

palaeorelief and the filling of the extensional fissures during the Toarcian (Figs 7 and 8. Elm , 1979

Elmi 1981b) This episode can be compared with the coeval events recognized in the central High Atlas

(STUDER & DU DRESNAY, 1980). These data have been interpreted as a dynamic change from

transtension to transpression (Favre et al., 1991). However, these compressions are scarce and they

may have been provoked by the antagonistic movements of the Atlas Tethys to the south and ot the

Maghrebian Tethys to the north (ELMI. 1978). More locally, they can depend on the biockage of some of

the small rhombic subbasins dividing the NW Maghreb. Similar data have been described by DUBAR

(1950) in the Jebel Bou Dahar (eastern High Atlas) where fissures opened in Megalodontids limestones

(Carixian to, perhaps, lowermost Domerian but no upper Domerian as it has been often stated) are tilled

by pink micrites containing rich brachiopod faunas and some ammonites and ranging from the middle

204

SERGE ELMI ETAL.

Toarcian (Bifrons zone) to the lower Aalenian (Opalinum zone) (see also the map in AGARD & Du

DRESNAY, 1965). The Toarcian uplift observed on the borders of the main western Algerian basins can

be compared with the thermal shouldering supposed by Favre et al. (1991) on the Atlantic border of

Morocco.

Aalenian and early Bajocian times were marked by tectonic and sedimentary instabilities which were,

at that time, general over all the NW Maghreb. The contrast between shoals (often islands), slopes and

deepening basins reached its climax. Along the northern Sahara, on the Moroccan Meseta and on the

Oran High Plains, carbonate platforms and sabkhas began to develop again. Marls accumulated in the

troughs, interrupted by gravity-flows transporting neritic material from adjacent platforms. Breccias

were frequent at the toe of the steepest scarps and pass laterally into calcareous or, even, quartzose

turbidites, indicating that some uplifted blocks have been eroded down to the basement, or at least to

Triassic-Lowermost Jurassic siliciclastics to provide a source. Zoophycos limestones or marls-

limestones interbeds were widespread along the less marked slopes, emphasizing the transitions to the

basins (Middle Atlas, TIemcen Domain). Incomplete, thin, neritic and often ferruginous sequences

capped the more prominent shoals. More generally, sedimentation was carbonate dominated from the

late Toarcian (Meneghinii Zone) up to the lower Bajocian (Sauzei to Humphriesianum Zones, depending

on the local conditions).

In the Atlas Domains, a second peak of deepening was diachronous: end of the early Bajocian or

beginning of the late Bajocian and is indicated by thick marls and turbidites. The final homogeneization

(or sag) stage was attained in the Atlas with the spectacular development of the intermediate carbonate-

platform. Coral build-ups were widespread in the High, Middle and Saharian Atlas. Deep basins

disappeared in the south and the west of the NW Maghreb. Quartzose sediments began to spread to the

North from the western High Sahara (Bechar).

Thus, the Aalenian-early Bajocian was a carbonate dominated interval between two periods of great

extent of the marly sedimentation. The first, presaged during the Domerian, was widespread during the

early to middle Toarcian; it seems to have been a global event often associated with anoxic conditions

(BaSSOULLET & Baudin, 1994). The inversion of the dynamic evolution began more or less early

during the middle Toarcian with the appearance of oxidized ferruginous beds. The end of the carbonate

period seems to be partly controlled by local and/or regional factors. In the TIemcen Mountains, it

happened during the late Bajocian and is coeval with the first input of siliciclastics in the Atlas Domain.

The change of the dominant sediment production appears to have been controlled by an inversion of the

palaeotectonic stresses. This change was initiated in the south (Atlas) and has progressed to the north

during the Bathonian and the Callovian (ELMI, 1978, 1981a).

In the TIemcen Domain, thick marls accumulated, but shoals and horsts often remained prominent

during the late Bajocian. These high areas began to be flooded and onlapped during the early Bathonian

(final or senile homogeneization stage). During Bajocian-Bathonian, extensional tectonics were

important and breccias are known everywhere. Redeposition of shallow-water sediments into deeper

trough is frequent (for instance: Raknet el Kahla Megabreccias in the Ksour Mountains). A rejuvenation

of the Saharian border gives the source of siliciclastics deposited in the Ksour turbidites. These events

are also reminiscent of those occurring in the Hebrides Basin of the northwestern comer of Europe with

the beginning of the Bearreraig Sandstone which indicates strong basin subsidence associated with

hinterland rejuvenation (MORTON, 1989, 1990). This is a classic lithosphere extension “following

?993) ° nVCn t * ierrna * ^ orn ‘ n § ' as bas been established in the North Sea (UNDERHILL & Partington,

In the north TIemcen and Tell-Rif Domains, a new deepening peak occurred late during the

Cal lovian-early Oxfordian. Clays and quartzose turbidites were widespread in these areas (Saida Clays

Formation). These data illustrate the decoupling between the northern deepening furrows and the

uplifted Southern regions (High Plains, Ksour).

■ however, the final differentiation stage, on a Maghrebian scale, is only reached during the middle or

late Oxfordian:

— acceleration of subsidence and deepening of the future Alpine Domains, where radiolarites extend

from the upper Bajocian to the lower Tithonian (Tell, Rif; recent data in OLIVIER et al., 1996);

Source:

JURASSIC OF WESTERN ALGERIA

205

— extension of a large delta from Morocco into the eastern Saharian Atlas (AUGIER, 1967;

Delfaud, 1975;Benest, 1985);

— from the Kimmeridgian onwards, the northern fringe of the delta became part of the late Jurassic

Carbonate Platform, extending from the High Plains to the Tlemcen and Preatlasic Domains (BENEST,

1985).

All these data are coherent with the model of aborted rifts or aulacogens (Du Dresnay, 1975;

1988b) developed along the Saharian Atlas and along the Tlemcenian Domain. But the evolution of

these two longitudinal furrows has been diachronous (ELMI, 1978; 1996b). The present study clearly

indicates that regional tectonic events overprint the global signal and that an eustatic sea-level chart

must be the result of comparisons between “different plates as tectonically uncoupled as possible”

(UNDERHILL & PARTINGTON, 1993).

PALAEONTOLOGICAL REMARKS

Hammatoceras roubanense Elmi sp. nov.

Figs 11, c-d; 19, a

1969. Hammatoceras nov. sp., Elmi & Benest p. 295.

1974. Hammatoceras nov. sp. 1, Elmi, Atrops & Mangold, pi.5, fig. 1.

ETYMOLOGY.— From the Rhar Roubane Mountains in Western Algeria.

TYPE locality.— Djorf Tisseddoura. North west of the Beni Snouss Khemis village.

TYPE LEVEL-— Bed 4 Ti 4 (Elmi, 1983: p. 405, fig. 3), Belai'ch Oncolitic Limestones (see Table 3);

Alticarinata Subzone, Gradata Zone, middle Toarcian.

TYPE MATERIAL.— Holotype (299 800), paratype (299 801) and figured topotype (299 802).

Collection Elmi, UFR Sciences de la Terre, Claude Bernard Lyon I.

DIAGNOSIS.— Hammatoceratids with prominent periumbilical tubercules (except the tirst whorls)

remaining strong until the beginning of the body chamber; gently curved inner part of the secondary

ribs; subogival ventral area without shouldering; relatively involute coiling.

DESCRIPTION.— All the specimens coming from Tisseddoura are well preserved internal casts. They

have been broken before their burial (Fig. 11 c). The inner whorls are often calcitic.

The holotype is a moderately involute and slightly compressed ammonite. The involution line is

approximately situated at middle height of the flank. The umbilical wall is vertical or subvertical and

moderately elevated all along the growth. The umbilical edge is gently curved between the tubercules.

The ventral area is regularily ogival and bears a neat carina. The overall shape ot the section remains

constant during the observable stages of growth of all the collected specimens.

The ornamentation consists in prominent periumbilical tubercules divided in ribs. The number ot ribs

per tubercule changes few during the growth. In consequence, they appeared to be more spaced in the

outer whorls. The tubercules are always prominent and even spinous in the inner nucleus. The ribs

(secondary ribbing) are monotonous but slightly flexuous on the ventral half of the whorl, and ventrally

projected. The ribs appear generally by pair issued from a large tubercule. A triplicate division is less

common. The transition from the tubercules to the ribs is progressive.

The paratype illustrates some complementary features of the ontogenic evolution of the

ornamentation. Untill a diameter of D=18 mm, the dorsal (inner) ornamentation consists only in short

primary ribs divided in 2 or 3 secondaries. Between D=18 mm and D=25 mm. the primaries become

stronger and more prominent. After, they change into spinous tubercules.

206

SERGE ELMI ETAL.

MATERIAL. — Seven well preserved specimens from Djorf Tisseddoura. Several from Sidi Yahia ben

Sefia (west of Sebdou), from the Zoophycos bearing Bayada Formation. The species is also widespread

in the Oujda Mountains (east Morocco) and in the Lusitanian Basin (Portugal).

MEASUREMENTS. — The dimensions given for the specimens are as follows: D. (diameter). Wh.

(whorl height). (Wli/D). Wb. (whorl breadth). (Wb/D). Ud. (diameter of umbilicus). (Ud/D).

Holotype (2990800): preserved diameter: c.125 mm.

D. 85;

Wh. 30.5 (0.35);

Wb. 22 (0.26);

Ud. 31 (0.36)

80.5;

29 (0.36);

21 (0.26);

29 (0.36)

77.5;

28.5 (0.36);

21.5 (0.27);

27 (0.34)

PHYLETIC REMARKS. — H. roubanense is the oldest known species belonging to the true

Hammatoceras lineage. It presents strong ressemblances with H. speciosum Janensch and H. insigne

(Zieten) which are more recent and separated by an interval corresponding to the Bonarellii Zone

(=Thouarsense Zone of NW Europe). The differences between the two homoemorphs H. roubanense

and H. speciosum are the shape of the ventral section (ogival on roubanense; quadratic and shouldered

on speciosum ) and the ribbing style (more straight on speciosum). The peculiar feature of roubanense

have not been observed in the large population of the Lyon area that we have studied.

ACKNOWLEDGEMENTS

This paper is a summary of the results obtained through the realization of several programs and

collaborations. It has been finalized in the scope of Peri-Tethys Programme Projects 95/96-38 and 42.

Personal grants have been obtained from the following supports: the franco-algerian programs 90MDU-

157 and 96MDU-359, the Geological Survey of Morocco, the “Entreprise nationale de l'lndustrie

miniere" (Algeria), the french “Centre national de la Recherche scientifique” UMR-5565.

Thanks to Noel PODEVIGNE (photographs of ammonites), Delphine FOUGEROUSE (drawings and text

processing). Nicol MORTON (Birkbeck College, University of London) has carefully corrected this paper

which has been greatly improved by his large knowledge of the Jurassic stratigraphy. Renaud Du

DRESNAY (Rabat) has read this paper and given very valuable informations on the moroccan outcrops

and bibliographic indications. Jacques THIERRY (Universite de Bourgogne, Dijon) have been an helpfull

referee and we have appreciated the constructive remarks of an other reviewer. Thanks also to Sylvie

Crasquin-Soleau for her editorial work.

This paper is dedicated to the memory of the late M'HAMED and RABIA(Oran, Algeria).

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Source:

The Jurassic of the southern Levant.

Biostratigraphy, palaeogeography and cyclic events

Francis HlRSCH Jean-Paul BASSOULLET ,2 \ Elie CARIOU' 2 ',

Brian CONWAY m , HOWARD R. FELDMAN 131 , Lydia GROSSOWICZ ",

Avraham Honigstein ", Ellis F. Owen 14 & Amnon Roseneeld

" Geological Survey of Israel, Malchei Yisraelstreet 30. 95501 Jerusalem, Israel

l2 ’Laboratoire de Geobiologie, Biochronologie et Paleontologie Humaine. Universile de Poitiers,

40. avenue du Recteur Pineau. F-86022 Poitiers Cedex, France

01 American Museum of Natural History. Department of Invertebrate Paleontology, Central Park, New York 10024. USA

""Natural History Museum, Cromwell Rd.. London SW7 5BD, U.K.

ABSTRACT

During the Jurassic, the Levant was part of the GondwanianTethys platform-shelf. The palaeotectonic setting of the Levant

consisted in relative lows and highs, controlled by differential rates of subsidence: the shallow Negev high in southern Israel

(900-2000 m), the Maghara basin in northern Sinai (3000 m). the central Israel Judean embayment (3000 m), extending to south

Antilebanon (Hermon), the northern platform of Galilee (1500-2000 m). extending to Lebanon and northern Syria. Clastics are

the result of the wearing down of the Arabian Massif in the South and South East. Yet. thickening of the early Oxfordian shales

in the offshore wells, points to derivation from some Iandmass in the West, now hidden below the Mediterranean. The

Gevar’Am trough, alongside the present Levant-coast, formed during the Tithonian. Volcanics mark the beginning and end of

the Jurassic (Asher at 197 my and Tayasir from 140 my onward). The stratigraphic sequence consists at its base of latentic

palaeosols (Mishhor formation). Marine deposition set in during Pliensbachian times. In the North, monotonous platform

carbonates (Haifa formation) are interrupted by the Oxfordian volcanics of Devorah. To the South, the fluviatile clastic

intervals of the Toarcian - Aalenian (Inmar formation) and Bathonian (Sherif formation) characterize the Negev facies. Shales

(Karmon formation) straddle the Bathonian - Callovian limit. A middle - late Callovian hiatus occurs in the Coastal plain. The

deposition of Oxfordian shales (Majdal Shams formation) is restricted to the basins of North Sinai, central Israel to south

Antilebanon (Judean embayement). Late Jurassic bioherms and reefs (Nir'Ani formation) form a belt along the coastal plain

area. In the Kimmeridgian, oolitic facies, shales and occasional sands recur (Nahar Sa'ar formation). The Tayasir volcanics and

Gevar’Am turbidites cover a truncation surface.

HlRSCH, F„ BASSOULLET. J. P.. CARIOU, E.. CONWAY, B., FELDMAN. H. R.. GROSSOWICZ. L.. HONIGSTEIN. A., OWEN, E. F.

& Rosenfeld, A., 1998. — The Jurassic of the southern Levant. Biostratigraphy, palaeogeography and cyclic events. In : S.

Crasquin-Soleau & E. Barrier (eds), Peri-Tethys Memoir 4: epicratonic basins of Peri-Tethyan platforms. Mem. Mus. man.

Hist. nal. , 179 : 213-235. Paris ISBN : 2-85653-518-4.

Source: MNHN. Paris

214

F. HIRSCH ETAL.

RESUME

Le Jurassique du sud Levant. Biostratigraphie, paleogeographie et cycles sedimentaires.

Durant lc Jurassique. la region du Levant faisait parlie de la plate-forme nord gondwanienne de la Tethys. La subsidence

varie selon les regions considerees. On distingue dans le Sud d’Israel, le haul fond du Negev (900 - 2000 m) : dans le Sinai le

bassin de Maghara (3000 m); au centre d'Israel le bassin de la baie de Judee (3000 m), prolonge jusqu’a l’Antiliban (Hermon);

la plate-forme septentrionale de la Galilee (1500 - 2000 m) qui s'etend au Liban et au Nord de la Syrie. L’essentiel des apports

clastiques provient de F erosion du Massif arabe au Sud et au Sud-Est. Cependant. Tepaississement des shales oxfordiens dans

les sondages offshore traduisent vraisemblablement l’existence d’une terre emergee silude en Mediterranee. Au Tithonien. la

fosse de Gevar'Am s’individualise parallelement a la cote actuelle du Levant. Le debut et la fin du Jurassique sont marques par

des episodes volcaniques (Asher a 194 Ma et Tayasir a partir de 140 Ma). La succession lithologique est la suivante. Succedant

it des depots lateritiques (formation de Mishhor). a la base du Jurassique, le regime marin s’etablit au Pliensbachien. Au Nord,

se deposent des calcaires monotones de plates-formes (formation de Haifa), interrompus a l’Oxfordien par I’episode volcanique

de Devorah. Vers le sud, des gres fluviatiles s'intercalent dans les intervalles Toarcien-Aalenien (formation de Inmar) et

Bathonien (formation de Sherif). La limite Bathonien-Callovien est marquee par le depot de shales (formation de Karmon).

Dans la plaine cohere, on constate une lacune du Callovien moyen et superieur. Les shales oxfordiens (formation de Majdal

Shams) se sont deposes dans les bassins de Maghara, du centre d'Israel et dans la partie meridionale de 1'Antiliban (baie de

Judee). Au Jurassique superieur. la formation corallienne de Nir'Am s'etire le long de la plaine cohere. Au Kimmeridgien, des

facies oolitiques, des shales et parfois des sables caracterisent la formation de Nahar Sa'ar. L'episode volcanique de Tayasir, et

les turbidites de Gevar'Am. d'age tithonien. reposent sur une troncature d'erosion.

INTRODUCTION

Since the monograph on the Jurassic of Israel and adjacent countries (PICARD & HlRSCH, 1987;

HlRSCH & Picard, 1988), contributions have been added, in the field of palaeontology and

biostratigraphy: palynomorphs (CONWAY, 1990), brachiopods (FELDMAN, 1987 ; FELDMAN et al.,

1991), ostracods (ROSENFELD et al., 1987a, 1987b, 1988. 1991), ammonites (CARIOU, this paper),

foraminifera and algae (BASSOULLET & GROSSOWICZ, this paper). In the more general field of

palaeogeography, interpretation of seismic profiles in the east Mediterranean Levantine basin and the

drilling activity offshore the Sinai coast (HlRSCH et al., 1995) have shed new light on the existence of a

thick sedimentary succession, including the Jurassic.

The biostratigraphy of the Jurassic in the Levant often exhibits an endemic character, related to that

of the southern Tethys shelf. The Jurassic succession of the Levant is well known from the boreholes in

Israel and from the outcrops of Gebel Maghara (Sinai. Egypt). Makhtesh Ramon, Hamakhtesh Hagadol

(Negev, Israel) and Mt. Hermon (Antilebanon). The Jurassic facies of the Levant shares its

particularities with African, Apulian and Arabian shelf-platforms. Boreholes supply a good insight in the

development of the Jurassic in the Levant, linking the over 2000 m of late Liassic to Kimmeridgian

strata of Sinai, similar to the Negev series, to the 2500 m of Middle to Upper Jurassic strata of Mount

Hermon. which give a good insight of the succession hurried under central Israel. The Jurassic of

Lebanon ressembles the succession of northern Israel. The Lower and Middle Jurassic series in

Makhtesh Ramon (central Negev) provides the stratotypes of the Mishhor. Ardon and Inmar formations.

The Middle - Upper Jurassic part of the Zohar formation and the late Callovian Matmor formation are

exposed in Hamakhtesh Hagadol (northern Negev). The latter represents a unique facies of the late

Callovian in the Middle East. The almost complete Middle to Upper Jurassic of Mount Hermon

(Antilebanon) exposes the Hermon. Majdal Shams and Nahar Sa'ar formations. The latter, also exposed

in eastern Samaria, is unconformably covered by the Tayasir volcanics.

The following sections were selected in the present study: the northern Israel Devorah borehole (I),

the Hermon exposure and the southern coastal plain Helez-Deep borehole (II); the northern Negev

Kurnub borehole and Hamakhtesh Hagadol exposure and western Negev Qeren borehole (III) and the

northern Sinai Hallal borhole and Maghara exposure (Figs I and 2). In the stratigraphic subdivision of

Israel, the Jurassic is comprised within the Arad group. The present review attempts to reduce the

number of formations to units, well defined in exposed stratotypes, though in a few cases subsurface

units, exposed nowhere, had to be retained (marked by *):

Mishhor, Asher*, Ardon, Inmar. Qeren, Haifa*, Daya*, Sherif*, Hermon, Zohar, Matmor, Niram*,

Majdal Shams. Nahar Sa’ar and Gevar’Am*.

JURASSIC OF THE SOUTHERN LEVANT

215

Fig. 1.— Location map and reference map to the Levantine countries. 1. Precambrian; 2, Palaeozoic- Tnassic; 3, Jurassic: 4

Mount Hermon; 5, Alpine thrust-front; 6. Neogene sinistral transform. (I) Galilee High; (II) Judean embayement; (III)

Negev High: (IV) Sinai Deep, with extension of lower Oxfordian Majdal Shams shales (shaded area) and total Jurassic

isopachs.

I-'IC. /. — Carle cle situation el de reference de hi region levantine. 1. Precarnhrien ; 2. Paleozoique-Trias : 3. Jurassique : 4

Mont Herman ; 5, chevauchement alpin ; 6. transformante senestre Neogene. (I) Hout fond de Galilee ; (III Bate de

Judee ; (III) Haul fond du Neguev ; (IV) Bassin du Sinai '; Isopaques du Jurassique ; (en grise) les shales oxfordiens de

Majdal Shams.

Source: MNHN, Paris

216

F. HIRSCH ETAL.

STRATIGRAPHIC OVERVIEW

Liassic

The Mishhor formation (GOLDBERG. 1969) consists of a bauxitic-lateritic palaeosoil and flint clays,

resting on an eroded Triassic landsurface. Its average thickness does not surpass 50 m. In the North of

the country it is replaced by the Asher volcanics. In the northern Sinai (Egypt) borehole of Gebel Halal,

500 m of red marls, some dolomites and sands of Norian (Granuloperculatipollis rudis Van Erve. 1977)

through early Liassic (Araucariasites australis Van Erve. 1977) underley the typical Mishhor pisolites

and red clays. Normally the Mishhor formation overlies a karstic surface leaching the Carnian Mohilla

or Noro-Rhaetian Shefayim formation Ga'ash borehole).

GEBEL KURNUB OEREN

MAGHARA

Fig. 2.— Stratigraphic sections. (I) Galilee High Devorah: the Liassic Asher volcanics are covered by the Middle Jurassic

carbonade Haifa formation, the volcanic Devorah tuffs, interstratified within the Oxfordian, followed by the Oxfordian

- Kimmeridgan Nahar Sa'ar formation. (II) Judean embayment Helez - Hermon: in the Helez borehole, the Liassic

Mishhor laterites are followed by Pliensbachian -Toarcian carbonates (Ardon). In the Ramallah borehole Aalenian

carbonates (Qeren) directly overlie the Mishhor laterites. Middle Jurassic is primarely represented by carbonates of

Hai fa - Hermon type. The lower Oxfordian is characterized by the development of the Oxfordian Majdal Shams shales,

which extend to the NW Negev and Sinai (Egypt). (Ill) Negev High (Kurnub- Qeren): The Negev section is

characterized by numerous elastics in the Kurnub borehole, becoming more carbonade toward the Qeren borehole. The

Liassic consists of the Mishhor and Ardon formations. The Aalenian Inmar formation is split by the Qeren carbonates.

The Middle Jurassic is diversified, comprising the Daya, Sherif, Zohar and Matmor formations'. The Upper Jurassic is

truncated in Kurnub. its development being well represented at Qeren by the Nahar Sa'ar formation. (IV) Maghara

Deep: Gebel Maghara exposure and Halal borehole: In the more clastic succession of the Maghara Deep, the Negev

units are still well represented, thought the total thickness has more than doubled. A-G : palynozones (after Conway.

1990).

Source: MNHN, Paris

JURASSIC OF THE SOUTHERN LEVANT

217

The Asher volcanics in northern Israel (Atlit, Haifa, Asher and Devora) consist of basalt,

agglomerates and tuffs (with few thin dolomite and shale interbeds), of 200-180 Ma (Lang & STEIN1TZ,

1989). The unusual thick basalt with enclaves of ?Triassic and Jurassic limestones and shales in Atlit

suggests a Late Triassic-early Liassic Graben-like trough over 4000 m deep.

The Ardon formation (NEVO, 1963) overlies the Mishhor formation. At Ramon, up to 50 m of marly

sandstones, sandy shales and sandy dolomites with algal mats and small molluscs represent a proximal

nearshore facies. To the north and west the formation develops into hundreds of meters of shallow

carbonates with evaporites. In the lowest section of the Ardon formation the foraminifer Orbitopsella

primaeva (Henson), a Pliensbachian taxon occurs. The upper section of the Ardon formation is assumed

to be mostly Toarcian. In the Hallal borehole (Sinai, Egypt) the Ardon formation reaches a thickness of

almost 800 m.

HELEZ HERMON DEVORAH

Fig. 2.— Coupes stratigraphiques. (!) Plate-forme de Galilee : les roches volcaniques de Asher sont recouvertes par la

formation carbonatee de Haifa, les tufs volcaniques de Devorah interstratifies d I'Oxfordien et la formation oxfordo-

kimmeridgienne de Nahar Sa'ar. (Ill La Baie de Judee de Helez a Hermon : dans le forage de Helez. les laterites

liasiques de Mishhor sont suivies des carbonates du Pliensbachien-Toarcien (Ardon). Dans le forage de Ramallah, les

carbonates de I'Aalenien (Qeren) reposent directement sur les laterites du Mishhor. Le Jurassique moyen est

represente pur les carbonates du type Haifa - Hermon. L'Oxfordien se characterise par le developpement des marnes

oxfordiennes de Majdal Shams, qui s’etendent au nord-ouest duNeguev el au Sinai (Egypte). (Ill) Haut-fond du Neguev

(kurnub-Qeren): la coupe du Neguev se distingue par son abondance en roches clastiques dans le sondage de Kurnub.

devenant plus carbonate en direction de Qeren. A I’Aalenien. les carbonates de Qeren s’imbriquent dans !a formation

de Inmar. Le Jurassique moyen est diversifie et comprend les formations de Daya. Sherif. Zohar et Matmor Le

Jurassique superieur est tronque a Kurnub tandis que dans le sondage de Qeren la formation de NaharSa ar est bien

developpee. (IV) Bassin de Maghara : dans la coupe du Gebel Maghara et du sondage de HalUd (Sinai), les unites du

Neguev sont representees, tandis que leur epaisseur totale est doublee. A-G : palynozones (d apres CONWAY, 1990).

Source:

218

F. HIRSCH ETAL.

Middle Jurassic

From the northern coastal plain (Ga’ash) to the north (Carmel, Galilee and Lebanon) over 1000 m of

dolomicrites, occasionaly anhydritic, build up an undifferenciated Aalenian to Oxfordian succession of

the Haifa formation (DERIN, 1974). The Aalenian interval of the Haifa formation is characterized by the

foraminifer Timidonella sp. The Bajocian interval contains Haurania and the Bathonian interval

Paleopfenderina salernitana Sartoni & Crescenti. The Callovian is represented by a lower interval

characterized by an assemblage of Kilianina sp., and an upper interval with Trocholina palasteniensis

Henson, 1948. The uppermost part of the uniform sedimentary regime of the Haifa formation comprises

micrites yielding the algae Pseudoclypeina and the foraminifer Levantinella egyptiensis (FOURCADE et

al., 1983) (ex Manghastia) of questionable late Callovian - early Oxfordian age.

Aalenian

The Inmar formation (NEVO, 1963), consisting of cross-bedded sandstones, interbedded with

kaolinitic clays, coally flint- clays and alunite horizons (GOLDBERY, 1982) was compared by LORCH

(1967) with the Aalenian Yorkshire lower estuarine beds. A thin marine intercallation at Ramon yields

Toarcian brachiopods (PARNES, 1980) and separates further North and West the Inmar elastics into a

lower and upper part. This marine intercallation, known as the Qeren formation (GOLDBERG, 1964),

consists of carbonates that in the boreholes west of Ramon, interwedge the fluvio aeolian -deltaic Inmar

elastics, replacing gradually the clastic lower part of the Inmar formation until it merges with the

underlying Ardon carbonates. These pelbiomicrites, oosparites and dolomicrites yield the Aalenian -

lower Bajocian foraminifer Timidonella sp. (Bassoullet) accompanied in the oolitic shoals at Helez by

Dictyoconus cayeuxi (Lucas) of the same age. At Maghara, an ammonite fragment was attributed to

Grammoceras or Sonninia, confering a Toarcian-Aalenian age to the Qeren formation (ARKELL. 1956).

In the Negev boreholes (Qeren. Makhtesh Qatan, Kurnub. Daya, Barbur, Boqer, Rekhme) and Sinai

(Halal) the upper part of the Inmar formation consists of sandstones and shales. The Inmar formation

passes from predominantly continental in Ramon to shallow marine to the west and north, consisting of

shaly marls (Rosh Pinna) with ostracods and calcareous nannoplancton (MOSHKOVITZ & EHRLICH,

1976). Further west and north the Inmar facies wedges entirely out, replaced by the carbonate facies of

the Haifa formation.

Bajocian

Nearly 100 m of marine cross-bedded sands with ripple marks, ferruginous oolitic dolomites and

plantiferous shales yield late middle and late Bajocian ammonites at Ramon (PARNES, 1981). The

arenaceous facies of the central Negev develops into the foremostly carbonatic facies of the Daya

formation (ELIEZRI in Coates et al., 1963) of the Negev boreholes, which is defined by the foraminifer

Haurania. It reaches in the Hermon section over 900 m of carbonates with volcanic intercalations.

In central Israel, the coastal plain and Judea, oosparites (Sederot facies) and micrites repleted with

poriferan spiculae (Barnea facies) may reach up to 400 m. Differing from the latter, the marly 500 m of

the Mahl and Bir Maghara formations (Al Far, 1966) in North Sinai, yield a plantiferous clastic

succession of shaly limestone, shales, shaly sandstone and coal streaks, followed by massive oo-

oncolitic coralline limestones, interstratified by thick marls and shales, rich in ammonoids (DOUVILLE,

1916; ARKELL, 1952, 1956; Parnes, 1981), topped by black shales, from which the ammonite

Thambitesplanus Arkell 1956 was determined (Parnes, 1981).

On the Syrian side of the Hermon. the 170 m medium - to fine-bedded oolitic organo-clastic,

ochreous-stained limestone (J2bt) yield brachiopods and bivalves (Razvalyaev, 1966). These

“calcaires ocres" (VAUTRIN, 1934) may correspond to a shaly horizon, interwedgind the oosparites and

spiculites of the Sederot and Barnea facies, close to the Bajocian-Bathonian boundary in the southern

coastal plain, around Helez (DERIN, 1974).

Source

JURASSIC OF THE SOUTHERN LEVANT

219

BATHONIAN

In most of the Negev boreholes, the Sherif formation (ELIEZRI in COATES et al., 1963) consists of

alternating sandstone, shale, pelmicritic and some sparitic limestone. The more shaly upper part of the

Sherif formation corresponds in the coastal plain and northenmost Negev to shales, rich in calcareous

nannoplancton, ostracods and foraminifers of late Bathonian - early Callovian age. The lower part of the

Sherif formation consists at Gebel Maghara of cross-bedded hematitic stained sandstones alternating

with limonitic shales with abundant plant remains and several coal-seams (Safa formation). The upper

part of the Sherif formation encompasses thin oolitic limestone with frequent shale and occasional thin

sandstone beds (Kehailia formation). The ammonite Micromphalites pustuliferus (Douv.) in its lower

part belongs to the early Bathonian. The shaley-carbonatic upper part yields Bullatimorphites bullatus

(d'Orb.), indicating the upper Bathonian or lower Callovian.

The bright bluish-grey limestones and dolomites of the Hermon formation (DUBERTRET, 1960) with

corals and brachiopods, that attain 700 m. are for Razvalyaev (1966) and KUTZNETSOVA & Dobrova

( 1995) entirely of Callovian age (J2C1). For DER1N (in GOLDBERG, 1969), the lower 600 m of the

Hermon formation is equivalent to the Bathonian interval of the subsurface Haifa formation.

Callovian

The alternating limestone, marl and shale series that was identified in the northern Negev boreholes

as the Zohar formation (COATES et al ., 1963) belongs entirely to the Callovian. The upper half of the

Zohar formation is well exposed at Hamakhtesh Hagadol (Kurnub). It consists in its lower part of

stromatoporoid and coral limestone, shale and sandstone, marl and limestone, placed in the middle

Callovian coronatum Zone (Gill & TlNTANT, 1975; Gll et al., 1985). Its upper part of alternating

marl, limestone and shale, is placed in the late Callovian athleta Zone (GILL & TlNTANT, 1975 and

Lewy, 1983). The section at Hamakhtesh Hagadol, above the Zohar formation, consists of the

alternating limestone and marl of the Matmor formation (GOLDBERG, 1963; emend. HlRSCH & RODED,

1996). Its lower part yields ammonites of the late Callovian athleta Zone (GILL & TlNTANT, 1975;

LEWY. 1983), with a bivalve and gastropod fauna still similar to that found in the Zohar formation. The

upper part of the Matmor formation consists of an oolite near base, alternating yellow shales, white

reefoidal and lagunar limestones. In its fauna of large bivalves and gastropods, the genera Purpuroidea

and Eunerinea (HlRSCH, 1979) show affinities with European Oxfordian taxa. The ammonite Peltoceras

solidum Spath still belongs into the late Callovian athleta Zone, whereas Pseudobrightia sp. puts the

uppermost interval to the late Callovian lamberti Zone. This interval also yields the foraminifera

FlabellocycloJina reissi Hottinger and Kurnubia gr. palastiniensis Henson. The Matmor formation

occurs in the boreholes of the NW Negev and NE Sinai, among which Hallal (Sinai) and Qeren (Negev).

The upper 100 m of the Hermon formation also consist of massive limestone and yield foraminifera

of Callovian age. Along the S-E slopes of Mount Hermon, the uppermost part of the Hermon formation

consists of alternating limestone and marl beds that yield abundant late Callovian belemnites, bivalves

and ammonites. Only a reduced, truncated Callovian interval is found in the coastal plain ot Israel.

Upper Jurassic

A reefoidal facies of biolithites of stromatoporoidea, corals, porifers and bryozoans occurs under the

coastal plain around Caesarea and in the Kokhav field is identified as the Nir Am formation (DERIN,

1974). In the Beer Yaakov, Gerar, Kfar Darom. Nirim, and Kissufim wells it overlies thin Majdal Shams

shales. The position of the Nir Am formation, between Hermon and Gevar Am formations confers

probably a mostly Oxfordian age to this formation, that reaches a thickness of 400 m in the Carmel

borehole.

220

F. HIRSCH ETAL.

Lower - Middle Oxfordian

The Majdal Shams formation (Saltzman et al., 1968) (200 m) consists of fossiliferous shales at

base, platy limestones and silicasites at top. The shales, with limonitic concretions, are interbedded by

marls and occasional thin limestone or dolomitic beds. The basal beds are extremely rich in small

pyritized ammonites, identified since NOETLING (1887) as the early Oxfordian Brightia socini zone, put

by ARKELL (1956) to the “Mariae” Zone. In his monography, Haas (1955) studied 7600 ammonites

from Majdal Shams, the exact level of which, within the 43 m thick lower marls, was retrieved by the

bed by bed collection reported by Razvalyaev (1966). The nuculide bivalve infaunal mobile detritus

feeders confirm the statement of Haas that the paramount darkish shale facies with pyritic dwarf forms

intimate to less aerated depositional environment - remarkably also occurring in the Renggeri Zone with

equal lithofacies in Switzerland, England and southern Russia. Vautrin’s overlying "Lusitanian” consist

of argillaceous marls and yellow limestone intercalated by marls holding fossils that ARKELL (1956)

puts to the Transversarium Zone. RAZVALYAEV (1966) puts the upper pelitomorphic limestones and

alternating dark marls “most probably to the Bimammatum Zone". The shale interval of the Majdal

Shams formation is present in the Israeli subsurface and in the nearly 70 m Tauriat shale of Gebel

Maghara (Sinai, Egypt). Thin bedded dark platy limestones with marl interbeds and a “tripoli”-like

yellow silicatic ledge of spiculitic limestone close the succession of the Majadal Shams formation in the

Hermon section. The dark highly pyritic shale with nodules and pyritised fossils, interbedded with few

limestones or dolomites (GOLDBERG & FRIEDMAN, 1974) that overlie the Zohar carbonates in the

Zohar-Kidod gas-field and in the coastal plain Helez-Kokhav oil-field, was termed "Kidod” by COATES

el al. (1963), a term largely followed by exploration geologists. The unequivocal early Oxfordian age

(Mariae Zone) of these shales on the base of ammonite-biostratigraphic data (Lewy, 1983;

Razvalyaev, 1966) in the exposures of Gebel Maghara (Sinai, Egypt) and Majdal Shams (Mt.

Hermon) was emphasized by Picard & HlRSCH (1987) and HIRSCH (1996). These shales are absent in

the area of Hamakhtesh Hagadol and boreholes of Qeren, Rehkme. Boqer and Gebel Hallal.

In many coastal plain wells, early Oxfordian shales rest directly on the thin calcarenite of the lower

Zohar formation (Callovian), showing karstification (GOLDBERG & BOGOSH. 1978; BUCHBINDER

1981).

The Majdal Shams formation reaches over 200 m in Central Israel (from the Helez Area eastwards to

Judea and Jordan Valley). In most of the Northern Negev and Northern Sinai, it is reduced to an average

of 100 m. In the offshore borehole of Delta-1, NW of Caesarea, a 200 m serie is still present, comprising

a carbonitic upper and shaley lower section. The 80 m lower section consists foremostly of black and

green shales rich in dinoflagellates. spores and coccolithes (MOSHKOVITZ & EHRLICH, 1980;

COUSMINER & CONWAY, 1990), of early Oxfordian age. Fragments of volcanics and of bio-intrasparites

were interpreted by FRIEDMAN et al. (1971) as cobbles or pebbles deriving from the shelf edge and

transported by turbitity currents into the depositional area of mudstone called "Delta facies”.

No trace of Oxfordian has been left in the larger and deep erosionfunnel around the Helez wells

(Barnea, Gevar Am. Helez, Talme Yafe).

Upper Oxfordian - Kimmeridgian

The uppermost part of the Hermon section exposes along its SE flank the succession, totalizing up to

180 m, of the Nahar Sa'ar formation (SALZTMAN et al., 1968). The echinoid limestone at base consists

of ca. 40 m ot massive limestones, yielding abundant spines as well as a few complete specimens ot the

echinoid Balanocidaris glandifera Muenster, for which a late Oxfordian - early Kimmeridgian age is

attributed by the foraminifer Alveosepta jaccardi (Schrodt, 1894) (DERIN, 1974). Follow 140 m ofwell

bedded yellow oolites, fossiliferous marls, with a massive limestone and more shale in its upper part at

Wadi E Shatr, yielding the indicative ostracod Hutsonia adunata Bischoff, 1990 (ROSENFELD &

Honigstein, this paper). Razvalyaev (1966) reports from dark-grey limestone and clayey limestone

the brachiopods Septaliphoria jordanica (Noetling), Somalirhynchia africana Weir, and S. somalica

Daque.

Source: MNHN, Paris

JURASSIC OF THE SOUTHERN LEVANT

221

The lower subdivision correlates with 90 m of massive limestone rich in echinoid radioles in

Lebanon, the flinty limestone, interstratified with yellow marls at Gebel Rokba at Gebel Maghara (Sinai,

Egypt). The upper subdivision is equivalent to a much thicker succession in Lebanon (DUBERTRET,

1975). There the 80 m of brown to yellow oolitic limestones and marls of the “couches jaunes

inferieures” or “couches d’Azour”, still with Alveosepia jaccardi (Schrodt, 1894), represent a lower unit.

Interwedged at this level, occurs the 180 m thick Bhannes volcanic complex, consisting of basaltic

sheets and weathered pillows, volcanic tuffs interfingered by lignitiferous and marls alternating with thin

limestones. Follows the middle unit of the limestone ledge of the “falaise de Bikfaya” and the upper unit

of the “couches jaunes superieures” or “couches de Salima” in which BlSCHOFF (1964) mentions

Berriasella richteri (Opp.), an upper Tithonian form for ARKELL (1956). The subsurface succession of

the Nahar Sa’ar formation is subdivided in the lower massive limestone of the Beersheba formation

(COATES et al, 1963), followed by the oolite, shale and sand succession of the Haluza formation

(COATES et al, 1963). The foraminifer Alveosepta jaccardi (Schrodt, 1894) confers a late Oxfordian -

early Kimmeridgian age to the lower 2 thirds of this section. In the Devora borehole of Galilee

interformational volcanics occur. A younger unit, consisting of the upper massive carbonate ledge, the

so-called Haifa Bay formation (Derin, 1974), apparently equivalent to the Lebanon “falaise de

Bikfaya”, was identified in the northernmost Israel boreholes (Haifa Bay, Hazon, Hula). This ledge is,

thought reduced in thickness, also found in the NW Negev boreholes (Qeren, Haluza), consisting of

carbonates associated with Campbeliella striata Carozzi and Alveosepta jaccardi personata Tobler,

1928, confering a Kimmeridgian age to this part of the formation. Such an age can now also be

attributed on the base of the ostracod Hutsonia adunata Bischoff, 1990, found in Lebanon in the Salima

Formation and topmost part of the Nahl Sa’ar formation at Ein Qinia (Hermon).

Tithonian

Generally regarded as a Lower Cretaceous unit (Beriassian - Hauterivian). the gray dark sandy shales

Gevar Am formation (Derin & Reiss. 1966), in borehole Negba-1 (from a core) yielded ammonites of

Late Jurassic (Tithonian) affinity (RaaB, 1962). This assumption is strenghtened by the finding by

MOSHKOVITZ & EHRLICH (1980) of Conusphaera mexicana Trejo. 1969 in the Gevar Am formation of

offshore well Delta-1. Recently DE HAAN (1997) found Late Jurassic palynofloras in the Gevar Am

shales of a number of wells of the coastal plain.

BIOSTRATIGRAPHY

The biostratigraphy of the Jurassic of Israel has been reviewed by Picard & HlRSCH (1987). It is

originally based on ammonites (Parnes, 1981; Lewy, 1983; GILL et al., 1985), calcareous

nannoplankton (MOSHKOVITZ & Ehrlich, 1976), foraminifers. algae and ostracods (Maync, 1966;

DERIN. 1974), bivalvia and gastropods (HlRSCH, 1979). and palynomorphs (pollen, spores, dinocysts

and acritarchs) (Conway, 1990). In the present paper, substantial additions are presented on ammonites,

palynomorphs, ostracods, brachiopods and foraminifers.

AMMONITES

The zonal subdivision proposed by PARNES (1981) was revised by ENAY & MANGOLD (1994). The

Jurassic of Israel and of the Hermon (south Antilebanon) belong palaeogeogiaphically to the Arabian

platform (HlRSCH. 1976; DERCOURT et al, 1993).

Provincialism

Ecologic constraints particular to such a large and shallow area as the Arabian Platform, gave

ammonites a markable endemic inprint (GILL et al, 1985; ENAY et al. 1987). This provincialism is the

cause of difficulties in the establishment of a precise stratigraphic correlation with european reference

sequences.

222

F. HIRSCH ETAL.

The proposed biostratigraphy uses species of the arabian bioma (ENAY & MANGOLD, 1994) at the

level of sub-zones. The establishment of a stratigraphic correlation with the european standard is based

on taxa common to both provinces. These are in general rather rare, or even absent, due to ecological or

sedimentary (hiatus) reasons. Such conditions prevail generally in the Jurassic of Israel and the Hermon,

with the exception of the transgressive pyritic ammonite bearing marls of the lower Oxfordian. This

short timespan of very relative opening of the Arabian platform edge to the pelagic Tethys- platforms

eased the comming in of Mediterranean Tethyan taxa, enabling stratigraphic correlation with Europe.

However, even during the lower Oxfordian, the confinement of the ammonite- population remained

strong, characterised by the dominance of Hecticoceratinae, with forms specific to the region. As a

result, a sample of 340 specimens from the basal level of the marls, was composed of 96 %

Hecticoceratinae, 1% Aspidoceratinae, 1% Perisphinctinae and less than 1% Phylloceratinae. Due to this

provincialism the proposed correlations (Table 1) remains necesseraly approximative.

BIOSTRATIGRAPHY

The zonal subdivision for the Hermon, Negev and northern Sinai proposed by PARNES (1981), LEWY

(1983) and GILL et al. (1985), is now revised on the base of the subdivision for Arabia proposed by

Enay & Mangold (1994).

The late Bajocian age of Thambites planus Arkell. 1956 and the early Bathonian age of

Micromphalites were proposed by ENAY & MANGOLD (1994) and differ from PARNES's original

assumption. The presence of genuine middle Callovian (Coronatum zone) and late Callovian (Athleta

and Lamberti Zones) is now clearly established at Hamakhtesh Hagadol. The Lamberti Zone is also well

represented at Majdal Shams, encompassing numerous ammonites.

New biostratigraphic results were obtained in the Callovian and Oxfordian stages.

Late Callovian.— Athleta Zone:

May be suddivided into two subzones, using indo-malagachy and/or arabian rather than the

submediterranean index-species (GlLLe? al., 1985):

— Pachyerymnoceras sp. Subzone: The association comprises Kumubiella compressa Gill, Thierry

& Tintant, Peltoceras sp. juv., Collotia sp. and Reineckeia nodosa Till. Pachyerymnoceras sp. reaches

with its living chamber a diameter of 190 mm. This relatively involute form belongs into the group of

Pachyerymnoceras kmerense Mang., which together with other species characterize the Trezeense

Subzone in Algeria (Mangold, 1988). It differs from the Algerian species by a larger number of

undivided ribs, becoming strong toward growth- end (10 on the last half whorl). This fauna is found

between subunits 33 et 41 of the Hamaktesh Hagadol section of Goldberg (1963).

— Solidum Subzone: The Indian species Peltoceras solidum Spath was selected as index-species by

Enay & MANGOLD (1994) for Arabia. In Arabia, it occurs in the upper part (T3) of the Tuwaiq

Limestone formation. An almost complete specimen was collected by LEWY in subunit 48 (GOLDBERG,

1963) at Hamaktesh Hagadol. The species is frequent toward the top of the Hermon Limestone.

“Lamberti” Zone:

— Pseudobrightia sp. horizon

The equivalent of the Lamberti Zone in the southern Antilbanon section of Majdal Shams is found at

the top of the Hermon formation. A thin horizon (0.30 m thick) of condensed platy marly limestone with

phosphatic grains is rich in ammonites, mostly flattened calcareous molcis of Hecticoceratinae:

Pseudobrightia sp., Hecticoceras (Putealiceras) intermedium (Spath), H. (Kheraites) ferrugineus

(Spath). H. (Brightia) aff. s alvadorii (P. & B.), H. (Putealiceras) douvillei (Jean.), Pachyerymnoceras

levantinense Lewy. Pseudobrightia s. st. individualises itself at the base of the Lamberti Zone in Europe

(CARIOU, 1984). The association found at the Hermon is of the same age. corresponding pro parte to the

Poculum Subzone of the submediterranean province (CARIOU, 1973; CARIOU et al., 1985). The

specimen of Pseudobrightia (coll. F. HIRSCH) in the scree of subunit 74 (GOLDBERG, 1963), top of

Matmor formation, at Hamaktesh Hagadol, is figurated as Brightia sp. (LEWY, 1983, PI. 1. Figs 17-18).

Consequently the top of the Matmor formation is still late Callovian and not early Oxfordian as assumed

Source: MNHN, Paris

JURASSIC OF THE SOUTHERN LEVANT

223

before. It is interesting to note that the end-Callovian condensed outer platform limestones at Mt.

Hermon express clearly a transgressive system tract, like the deposits of the same age in western Europe

(RlOULT et al., 1991).

LOWER Oxfordian.— The lower Oxfordian at the Hermon is represented by tens of m of marl with

small pyritised ammonites (Majdal Shams formation). This facies ressembles the “ Creniceras renggeri

marls” of the Jura Range, with which it shares several species (ENAY. 1966), among which Creniceras

renggeri (Opp.). The Hermon fauna, first described by NOETLING (1887) and globaly attributed to the

Socini Zone, was described in greater detail by Haas (1955), who correctly interprets the Socini Zone as

the southern Tethys equivalent of the Mariae Zone. RAZVALYAEV (1966) gave a precise stratigraphic

ammonite species distribution. FREBOLD (1928) has proposed a subdivision into 2 zones: the

Hecticoceras socini Zone at the base and the Oecotraustes scaphitoides Zone at top. The outcrop

conditions do not permit the continuous bed by bed collection. Two levels have delivered hundreds of in

situ pyritised ammonites, one 2.50 m thick, at the very base of the sequence, the other, less abundant, ca

40 m higher. The two assemblages are clearly distinct:

— Socini horizon: abundant Hecticoceras socini (Noet.), associated with H. kautzschi (Noet. in

Haas), H. separandum Haas, H. solare Haas, H. schumacheri (Noet.), H. chatillonense de Lor., H. cf.

guthei (Noet.), H. coelatum Coquand, Taramelliceras cf. langi (de Lor.), Euaspidoceras subbabeanum

(Sintzow), E. douvillei (Coilot), E. subcostatum (in Haas, non Spath), Perisphinctes bernensis de Lor.,

Mirosphinctes aff. robyi (de Lor.), Sowerbyceras helios (Noet.).

— Socium horizon: the very characteristic Hecticoceras socium Haas is associated with H. syriacum

Haas, H. bonarelli de Lor., H. kautzschi (Noet.), Creniceras renggeri (Op.), Euaspidoceras sp.,

Properisphinctes sp., Mirosphinctes sp.

Correlation of both horizons with Europe can be made on the base of comparison with figurated

european forms, the stratigraphic distribution of which in the fold of the Mariae Zone is precisely known

(SCHIRARDIN, 1958; GYGI, 1990; VlDIER et al., 1993; FORTWENGLER et al., in press).

Table 1. — Ammonite levels in the Levantine series and their probable equivalences with submediterranean Europe zonal

scheme. The units with asterisk are new.

Tableau I .— Niveaux a ammonites des series du Levant et tears equivalences probables avec le schema de zonation d'Europe

sub-mediterraneenne. Les unites avec un asterisque sont nouvelles.

EUROPE (SUBMEDITERRANEAN PROVINCE)

STAGE SUBSTAGE ZONES SUBZONES

LEVANT

(characteristic ammonites)

TITHONIAN

? Virgatosphinctes

middle Plicatilis

Euaspidoceras gr. perarmatum

Cordatum

? Peltoceratoides

Oxfordian Praecordatum

lower Mariae

Scarburgen.se

Hecticoceras socium*

Hecticoceras socini

Lamberti

Lambeni

upper Poculum

Pseudobrightia sp.*

callovian Col loti formis

Athleta

Trezeense

Peltoceras solidum

Pachverymnoceras sp.*

middle Coronatum

Kurnubiella ogivalis

EARLY CALLOVIAN -

LATE BATHON1AN ?

Bullatimorphites cf. bullatus

BATHONIAN LOWER Zigzag

Micromphalites

Parkinsoni

Thambites planus

upper Garantiana

Ertnoceras mogharense

bajocian Niortense

Ermoceras runcinatum

Laeviuscula

Dorsetensia

Otoites

224

F. HIRSCH ETAL.

The Socini horizon is equivalent to the Scarburgense Subzone. The Socium horizon would represent

the top of the Scarburgense Subzone and the Praecordatum Subzone.

PALYNOMORPHS

The zonation was established on the base of the first appearance of the Jurassic palynomorphs in

Israel and their correlation with their occurence in other parts of the world.

?Late Puensbachian to middle Bajocian Applanopsis turbatus Zone. — Terrestrial

palynomorphs belong to a floristic province extending across north Africa, Arabia and into Iran and

Afghanistan. Boreal floras are dominated by coniferalean disaccate pollen, whereas, northern

Gondwanean floras are subtropical, characterized by non-disaccate coniferalean pollen ( Corollina,

Applanopsis)-, as well as, Filiciales incertae sedis and Bennettitalean floral elements (LORCH, 1967;

CONWAY, 1990), disaccate pollen are absent to rare. Poor floristic diversity and limited evolution (at

least until late Oxfordian times) indicates strong climatic restrictions in the Levant province.

Strata from the Mishhor. Ardon, Inmar and Qeren formations, although some are marginally marine,

contain dinocysts of the Applanopsis turbatus Zone (including Nannoceratopsis pellucida Deflandre,

1938 and Dapsilidinium? deflandrei (Valensi, 1947)) that correlate well with coeval boreal suites.

Late Bajocian Korystocysta kettonense Zone (late Bajocian) Dichadogonyaulax

SELLWOOD ll Zone (latest Bajocian). — In Israel, Mid-Jurassic assemblages from shallow shelf

depocentres indicate normal marine salinities, they are dominated by proximate dinocysts with epitractal

archeopyles ( Dichadogonyaulax and Korystocysta), together with small proximate cysts with apical

archeopyles (Ellipsoidictyum, Sentusidinium). These elements typify Tethyan warm water faunas

elsewhere. Despite this close affinity and not withstanding their limited diversity the assemblages

correlate well with boreal assemblages. Differences on the species level are probably due to ecological

factors. In the Negev, strata from the upper part of the Inmar and Daya formations contain the taxa

defining this Zone. In northern and central Israel it defines a portion of the Haifa formation.

BATHONIAN: ENERGLYNIA ACCOLARIS ZONE. — There is a continuity of ecological conditions in the

Levant. No major evolutional changes occur, ctenidodinoid elements remain dominant, as in Europe,

and are reinforced by the entry of Energlynia. The skolochorate cyst Systematophora appears, whose

achme is younger.

Low diversity characterizes Bathonian assemblages of Israel, similar assemblages occur in

contemporaneous intervals from NE Spain, Portugal and in NE Libya (SaRGEANT, 1976; FENTON et al.,

1980; Thusu & VlGRAN, 1985). Although boreal assemblages appear more diverse, provincialism is

difficult to define, many taxa are widespread, even with global distribution. This zone defines the Sherif

formation and coeval portions of the Haifa and Hermon formations.

CalloviaN: POLYSTEPHANEPHORUS CALATHUSZONE — In Israel; low diversity again characterizes

Callovian assemblages, and elsewhere in the Tethyan realm. The most distinct change in warm neritic

Late Jurassic dinocyst assemblages is the acme of skolochorate cysts ( Adnatosphaeridium.

Coinpositosphaeridium, Emmetrocysta, Polystephanephorus, Surculosphaeridium and Systematophora).

There is a decline of ctenidodinoid elements and small proximate cysts with apical archeopyles

(Ellipsoidictyum. Sentusidinium). Large gonyaulaccid cysts with precinglar archeoyples are scarce. The

Zone defines the Zohar and Matmor formations as well as the corresponding interval of the Haifa

formation.

Oxfordian: Millioudodinium nuciformis Zone (early to middle Oxfordian) and

Epiplosphaera reticulospinosa Zone (middle to late Oxfordian).— In Israel, Oxfordian

assemblages indicate normal marine salinities and continue to be characterized by skolochorate cysts

morphologically related to Systematophora, which are more numerous in the Tethyan realm. Cavate

dinocysts are rarer than in boreal assemblages. These features indicate some degree of isolationism or

provincialism, although, there are broad similarities with western Neotethyan suites in Europe,

differences being largely at species level. There is a dramatic entry of large gonyaulaccid dinocysts

(Hystrichogonyaulax, Millioudodinium) that rise to dominate Oxfordian assemblages of Israel. These

JURASSIC OF THE SOUTHERN LEVANT

225

zones define the Majdal Shams and Nahar Sa’ar formations. The lower zone also defines an age-

equivalent interval of the Haifa formation.

OSTRACODS

The data on Jurassic Ostracods that were described from Gebel Maghara (Sinai. Egypt), Makhtesh

Ramon, Hamakhtesh Hagadol (Negev) and Majdal Shams (Hermon), are summarized herein

(ROSENFELD et al., 1987a. 1987b, 1988, 1991 and in press).

Lower-middle Liassic Bisulcocypris oertlii Assemblage Zone.— At Makhtesh Ramon

(south Israel) shales at the base of the Ardon formation yield the non-marine ostracods Bisulcocypris

oertlii Gerry, Fabanella ramonensis Rosenfeld & Honigstein and Laevicythere sp. In drillings, the

marine Ektyphocythere cf. vitilis (Apotolescu, Magne & Malmoustier) may set in, but not in the same

layers as the nonmarine taxa, pointing to alternating environments of fresh-brackish water and shallow

sea. The nonmarine fauna is endemic at the specific level, whereas the marine form shows european

affinity.

Toarcian-Aalenian Ektyphocythere bucki Assemblage Zone.— At Gebel Maghara (Sinai,

Egypt) the clastic upper Inmar formation yields frequent Cytherella ? toarcensis (Bizon), rare to

common Ektyphocythere bucki (Bizon), Isobythocypris oval is (Bate & Coleman) and Praeschuleridea

inmarensis Rosenfeld & Gerry and Kinkelina kadeshensis Rosenfeld & Gerry. The environment of

deposition was warm shallow marine. The assemblage shows affinities with european forms.

Bajocian Glyptogatocythere magharaensis Assemblage Zone.— In the shales, that

alternate with the carbonates of the Daya formation at Gebel Maghara, the frequent Glyptogatocythere

magharaensis Rosenfeld & Gerry and the common to rare Cytherella bashai Rosenfeld & Gerry,

Monoceratina striata Triebel & Bartenstein. Rutlandella transversiplicata Bate & Coleman and

Ektyphocythere zerqaensis Basha are characteristic and restricted to this assemblage zone, whereas

Glyptocythere huniensis Basha and Bairdia aff. B Jones proceed higher. The environment of deposition

was warm shallow marine, though Monoceratina indicates somewhat deepening of the facies. The

assemblage still shows affinities with european forms, though more taxa and the dominant taxon are

endemic (Israel, Jordan).

Bathonian Progonocythere honigsteini - Fastigatocythere bakeri Assemblage Zone.—

In the Sherif formation at Gebel Maghara. this assemblage zone is dominated by Progonocythere

honigsteini Rosenfeld & Gerry, Fastigatocythere bakeri (Basha), Praeschuleridea hornei Rosenfeld &

Gerry, and Zerqacythere subiehensis Basha. Further occur for the first time: Glyptogatocythere malzi

Basha, Ektyphocythere shulamitae Rosenfeld & Gerry. E. aardaensis Basha and terquenuda goldbergi

Rosenfeld & Gerry. The environment of deposition was warm shallow marine and faunal affinity

remains dominantly provincial (Israel. Jordan).

Callovian Ektyphocythere zoharensis Assemblage Zone.— In the rather rare shale

intercalations of the Zohar formation at Gebel Maghara Ektyphocythere zoharensis Rosenfeld & Gerry

and Terquenuda gublerae (Bizon) are found. Throughout the Zohar and lower Matmor formations at

Hamakhtesh Hagadol (Negev. Israel) an assemblage is found that comprises E. zoharensis Rosenfeld &

Gerry. Bairdia aff. hi Ida Jones. Afrocytheridea faveolata Bate. Progonocythere aff. parastilla Whatley

and Micropneumatocythere laevireticulata Rosenfeld & Honigstein. In the upper part ol the Matmor

formation, the assemblage of E. zoharensis Rosenfeld & Gerry has a different composition. Here, along

with the taxa of the assemblage found below, now also appear Exophthalmocythere? kidodensis

Rosenfeld & Gerry. Mandelstamia hirschi Rosenfeld & Honigstein, Cytherella index Oertli and

Oligocythereis aff. fullonica (Jones & Sherborn). The environment of deposition of the Zohar and

Matmor formations is shallow warm marine and the faunal affinity is widely endemic (Israel, Saudi

Arabia).

Early Oxfordian Exophthalmocythere? kidodensis Assemblage Zone.— The Tauriat

shales (Majdal Shams formation) at Gebel Maghara yield Exophthalmocythere? kidodensis Rosenfeld &

Gerry, Progonocythere aff. parastilla Whatley and Terquemula gublerae (Bizon). At the Hermon, the

226

F. HIRSCH ETAL

Majdal Shams formation yields an abundant assemblage, comprising next to E. ? kidodensis Rosenfeld &

Gerry and T. gublerae (Bizon), also T. cf. martini (Bizon), Cytherella cf. umbilica Bate, Monoceratina

stimulea (Schwager) and M. cf. sp. B Bate, as well as Cytherelloidea atlantolevantina Rosenfeld &

Honigstein, Eucytherura oxfordiana Rosenfeld & Honigstein, Acrocythere dubertreti Rosenfeld &

Honigstein, Homerocythere hermonensis Rosenfeld & Honigstein and Oligocythereis irregularis

Rosenfeld & Honigstein. The environment of deposition of the Majdal Shams formation at the Hermon

is definitely of deeper water with euxinic bottom conditions. The faunal affinity of ostracods remains

endemic, notwithstanding a slight relation to western Europe, the Tethyan oceanic barrier held this

province apart from its boreal eurasiatic counterpart north of the Tethys.

Late Oxfordian - Kimmeridgian Hutsonia adunata Assemblage Zone.— In the Nahar Sa’ar

formation at Ein Quniya (Hermon) as well as in boreholes (Qeren, Haluza, Boqer, Kohal, Beersheva and

Hazon) an assemblage identical to the one described from the couches d'Aazour and calcaires de Salima

of Lebanon occurs (BlSCHOFF, 1990). There stratigraphically important representatives of the genera

Schuleridea and Hutsonia have a range from late Oxfordian - Kimmeridgian and possibly Tithonian.

BRACHIOPODS

Brachiopods of the region have been described by DOUVILLE (1916), MUIR-WOOD (in HUDSON,

1958), FELDMAN (1987) and by FELDMAN et al. (1982, 1991).

The affinity of these faunas is generally endemic to the Ethiopian province, the geographical

distribution of which is wide, including a Gondwanian shelf crescent from east to north Africa (Somalia,

Kenya, Tanzania, Arabia, the Levant, Egypt. Tunisia and the Maghreb). Middle to Upper Jurassic

brachiopods described from Saudi Arabia, Israel, Egypt and Tunisia, while containing many genera and

species common to all four subregions, also contain elements that are characteristic of the area of origin,

an observation also made for bivalves, e.g. Eligmus (HlRSCH, 1979).

The Ethiopian province is suspected to have been invaded in the Early Jurassic from the north

(Europe) and thereupon isolated for the remainder of the Jurassic, developing special morphological

features which distinguish them from their original stock, a phenomenon also common in Callovian

nerineids. Though Jurassic brachiopods from Cutch (India) were broadly correlated with lower

Bathonian to Oxfordian faunas of Europe (KlTCHIN, 1900; SPATH, 1927-1933; ARKELL, 1956), it is

suggested that a number of genera and species from Israel, Saudi Arabia and Cutch are very closely

related. The rhynchonellid Pycnoria described by COOPER (1989) from the upper Bathonian - Callovian

of Saudi Arabia is almost certainly congeneric with Rhynchonella fornix Kitchin, 1900 and R. nobilis

Kitchin of Cutch. The genus Schizoria described by COOPER (1989) from the upper Bajocian of Saudi

Arabia appears to be represented by R. assymetrica Kitchin and the specimens of Globirhynchia crassa

Cooper from late Bajocian beds, are similar to specimens described as R. versabilis Kitchin. Among

Terebratulida, species of Kutchithyris , encountered in Israel and Saudi Arabia, are very similar in

external morphology to those of Cutch. The works of Weir (1925, 1929) and MUIR-WOOD (1925) give

the impression of a rhynchonellid-dominated fauna of comparatively little diversity in the middle Upper

Jurassic of Somalia. A similar impression is obtained from Tunisia (DUBAR, 1967), leading to the

conclusion of a closer faunal and ecological relationship of these areas than actually exist. Likewise,

Bathonian to Oxfordian beds in south Israel draw a closer comparison with the Somalian fauna than with

the Saudi Arabia fauna monographed by COOPER (1989). Yet, a number of terebratulid species that

occur in both South Arabia and Israel have not been recognized from Somalia and Tunisia.

Rhynchonellida common to all tour areas include unibiquitous Somalirhynchia and Daghanirhynchia,

but the genera Amydropthychus, Conarosia, Echysoria , Coloptoria, Eurysites, Lirellarina, Nastoria and

Strorgyloria of COOPER (1989) do not occur in southern Israel, Somalia or Tunisia. However the genus

Pycnoria occurs in Bathonian to Callovian beds in Gebel El-Maghara (FELDMAN, 1987) and Saudi

Arabia (COOPER, 1989) and may also occur with forms such as Schizoria from the Bajocian,

Burmirhynchia Bajocian - Callovian and Globirhynchia in both Gebel El-Maghara (Sinai, Egypt) as well

as Cutch (India).

JURASSIC OF THE SOUTHERN LEVANT

227

FORAMINIFERA

The extensive studies of MAYNC (1966), Derin & Reiss (1966), DERIN & GERRY (1972) and Derin

( 1974) have laid the base to a comprehensive microfacies distribution, mainly based on foraminifera and

algae. Jurassic foraminifera, in need of a revision in the field of taxonomy and biostratigraphy, were

given special attention in the Peri-Tethys project. Lately, KUZNETSOVA & DOBROVA (1995) and

KUZNETSOVA et al. (1996) have added information on Jurassic foraminifera from Syria.

LlASSIC.— From the few outcrops of the Ardon formation in Maktesh Ramon (Negev), the exact age

of the marine Jurassic basal transgression in that part of the Levant is still uncertain. The formation only

yielded Glomospira sp. with alga Thaumatoporella parvovesiculifera Raineri, in restricted lagoonal

facies, taxons without chronostratigraphical value.

A revision of the subsurface Liassic confirmed the presence of Orbitopsella primaeva (Hottinger) in

the lowest portion of the Ardon formation in boreholes of the coastal plain (DERIN, 1974), indicating a

Pliensbachian age for the Liassic transgression. Forms previously identified as Orbitopsella aff.

praecursor (Giimbel) and considered as indicative of the "Orbitopsella praecursor Zone"

(Pliensbachian) are referable to Timidonella sp. In the same interval occur Gutnicella gr. cayeuxi

(Lucas), Spiraloconulus cf. perconigi (Allemann & Schroeder) and at the top. LimogneUa sp. All these

forms are elsewhere known in the Tethys from Aaleno-Bajocian time span.

MIDDLE JURASSIC.— To the Bajocian are related Amijiella amiji (Henson) and dasyclad Selliporella

donzellii Sartoni & Crescenti, and to the Bathonian Paleopfenderina salemitana Sartoni & Crescenti.

However, the precedently quoted Meyendorffina bathonica Aurouze & Bizon and Orbitammina

elliptica (d'Archiac), well known late Bathonian markers in western Europe, are actually a new species

of flattened Kilianina. Its range is to be placed in early and / or middle Callovian and it is often

associated with Praekurnubia and small primitive Kurnubia (K.) variabilis Redmond. The presence ot

Satorina apuliensis Fourcade & Chorowicz was not confirmed. In the Coronatum Zone (middle

Callovian) Praekurnubia crusei Redmond and small Kurnubia (K. variabilis Redmond, K. bramkampi

Redmond) are widespread. At Hamaktesh Hagadol, the larger Kurnubia (K. palastiniensis (Henson). K.

cf. wellingsi (Henson)), together with small species, Flabellocyclolina reissi Hottinger and Steinekella

cf. steinekei Redmond appear. F. reissi seems only present in the upper Callovian.

LATE Jurassic.— Lower Oxfordian can be characterized by " Mangashtia " egyptiensis Fourcade et

al. (Derin, 1974). The widespread Alveosepta jaccardi biozone is well represented (upper Oxfordian-

Kimmeridgian). At the top of the range zone of this taxon Anchispirocyclina praelusitanica Maync also

occurs (MAYNC, 1966). Algae include Pseudoclypeina and Clypeina jurassica Favre.

PALAEOGEOGRAPHY

For a correct understanding of the Jurassic palaeogeographic setting of Israel prior to the mfra-

cretaceous truncation, one has to move the Golan - Jordan side about 100 km back to the south. In the

south, the Negev High consists of the Avdat and Massada-Jordan “blocks", separated by the Kurnub

"basin” (GOLDBERG & FRIEDMAN, 1974). Plunging toward the NW. the "nose" of the Negev High

separates the depotcenters of the North Sinai (Maghara-Halal) from the Central Israel trough (Helez-

Ramallah- Hermon) of the Judean embayment (HlRSCH, 1985). To the North, the overall thinner Jurassic

column represents the Galilee High that extends to the adjacent Lebanon and northern Antilebanon

(HlRSCH, 1985).

LOWER Jurassic (Fig. 3).— Major uplift took place at the Rhaetian - Liassic boundary, resulting in

denudation, karst and truncation processes. In northern Israel, a transversal trough was filled by pre-

Toarcian Asher volcanics, the wearing down of which produced the materials found in the laterites ol

the Mishhor formation, covering most of Israel and adjacent areas (PICARD & HlRSCH. 1987).

228

F. HIRSCIl ETAL.

Fig. 3.— Early Toarcian facies map. The early Toarcian is

represented by an interval within the huge mass of

platform carbonates with evaporitic layers that build

up the Ardon formation. Its existence toward Lebanon

is not clear and the interval may onlap directly the

Asher Basalts (VV) in the northern part of Israel. It is

estimated to consist on the slope toward the Judean

embayment of over 200 m, thickening towards the

central axe of the embayment to the order of 500 m. 1,

basalts (193-194); 2. carbonates and evaporites.

FlG. 3.— Carte des facies au Toarcien inferieur. Le Taarcien

inferieur represent4 un intervalle dans la masse

immense des carbonates de plate-forme el evaporites

qui constituent la formation de Ardon. Son extension

vers le Liban n'est pas claire, intervalle pouvant

couvrir les basaltes de Asher (VV) dans le nord

d'Israel. En bordure de la baie de Judee I’intervalle

peut atteindre 200 m et s'epaissit vers I'axe du bassin

(de I’ordre de 500 m). 1. basaltes (193-194) ; 2.

carbonates et evaporites.

Fig. 4.— Early Callovian facies map. This ca. 100 m thick

interval subdivides in tectono-sedimenlary zones: I.

calcarenites (Haifa); II. calcarenites (Brur) of the

“unstable zone" . truncated by a karstic event; III.

shales (Upper Sherif-Karmon), calcarenites and marls

(lower Zohar); IV. massive calcarenites (Hermon). 1.

carbonates; 2, limestones and marls; 3, eroded.

FlG. 4.— Carte des facies du Callovien inferieur. L'intervalle

d'environ 100 m d’epaisseur se subdivise en zones

tectono-sedimentaires : I. calcarenites (Haifa) ; II. les

calcarenites (Brur) de la 'zone instable’ sont

tronquees par un evenement karstique ; III, shales

(Slierif superieur-Karmon), calcarenites et marnes

(Zohar) : IV, calcarenites massives (Hermon). /.

carbonates ; 2. calcaires el marnes ; 3. erode.

Source: MNHN, Paris

JURASSIC OF THE SOUTHERN LEVANT

229

Fig. 5.— Early-middle Kimmeridgian facies map: consists of

reefs, oolites, shales and sands (Nahar Sa'ar). Eroded

by the infra-Cretaceous uplift along the present Levant

coast and in the SE Negev. 1, oolithes; 2. marls; 3,

limestones; 4, reef; 5, eroded.

Fig. 5 .— Carte des facies du Kimmeridgien inferieur et

moyen : se compose de reefs, oolites, shales et sables

(Nahar Sa'ar). Tronque lots du soulevement infra-

Cretace le long de la cote actuelle du Levant et dans le

Neguev du SE. I, oolithe ; 2, marnes ; 3, calcaires ; 4,

ree f; 5, erode.

Fig. 6. — Late Tithonian facies map. This interval belongs

virtually to the infra-Cretaceous tectono-

environmental phase. It is marked by wide denudation,

Tithonian -Hauterivian volcanics (Tayasir) and

turbidites (Gevar 'Am canyon). L alkalin basalts (140-

115); 2. basic intrusion; 3. shales; 4. eroded.

Fig. 6 .— Carte des facies du Tithonien superieur. Cet

inten’alle appartient virtuellement a la phase tectono-

environnementale infra-Cretace. II est marque par tine

denudation etendue, un volcanisme tithonique -

hauterivien (Tayasir) et par des turbidites (Canyon de

Gevar’ Am). 1, basaltes alcalins ; 2. intrusions

basic/ties ; 3, shales ; 4. erode.

Source:

230

F. HIRSCH ETAL.

During the middle - late Liassic transgressions, true marine platform carbonate regime developped

fast in the depocenters of north Sinai and of the Judean embayment. Clastics, the result of the wearing

down of the Arabian massif to the South and South East, and intersparsed oolites and evaporites mark

the proximal sides of the basins. Shales replace the sandstones of the upper Inmar formation and the

carbonate bodies of Ardon and Qeren merge toward the distal part of the basin. In northern Israel,

Lebanon and north Antilebanon platform all clastics have vanished and carbonates persist without

interruption from the Liassic to the Upper Jurassic (Haifa formation).

MIDDLE JURASSIC (Fig. 4).— From the northern Israel (Haifa formation) to the central Israel and

Israel coastal plain and Hermon (Hermon formation), calcarenites are interwedged in micrites.

In southern Israel (Negev) the interplay of continental (Arabian massif) arenaceous with littoral- tidal

shales and carbonates characterize the Zohar formation. The micrites are interbedded with shale and a

few thin sandstones of subordonate non fluviatile origin.

Contrasting with the apparent continuous platform sedimentation regime of north Israel, the emersion

of part of the coastal plain belt, witnessed by karst phenomena in several boreholes (Buchbinder et ai,

1984), caused erosion and truncation of the Callovian carbonates. This infra-Oxfordian unconformity

(POX) resulted in the filling of a karstic landscape by the transgressive early Oxfordian Majdal Shams

shales.

LATE Jurassic. — The Oxfordian palaeogeography is well delimited by the distribution of the lower

- middle Oxfordian shale-facies (Majdal Shams). Absent from the northern High of Galilee (1) and

southern High of the Negev (III), the shales reach 200 m thickness along the axis of the Judean

embayement (II) and less than 100 m in the Sinai deep (IV). Volcanic tuffs occur in northern Israel

(Devorah). In northern and central Israel, including the NW Negev, the lower Kimmeridgian (Fig. 5) is

developped in the shallow marine facies of oolites, marls and shales of the Nahar Sa’ar formation.

A different palaeogeography is initiated by the Tithonian (Fig. 6) regional uplift, generating the Infra-

Cretaceous unconformity. In the wells drilled into the canyons of the “Helez erosion embayment” nearly

all Callovian and Upper Jurassic formations are missing, as they were removed by submarine Tithonian

- Hauterivian chanelling of the turbiditic Gevar Am shale. Subareal truncation reached down to the

Dogger in the Central Negev and to Triassic- Palaeozoic levels in the southern Negev.

TECTONO-EUSTATIC CYCLIC EVENTS

Several transgressive systems tracks or highstands were individualized, characterized by condensed

facies and ferruginous oolites. Ammonites enable precise dating at Bajocian, early Bathonian, early late

Bathonian, middle - late Callovian and latest Callovian-lower Oxfordian intervals. Their relatively good

synchronism with system tracts of same signification in Europe shows the importance of tectono-

eustatism as factor of sedimentary control, including 3rd order scale phenomena in the sense of Haq et

al. (1988). At longer term, the Jurassic transgression is here neatly expressed, by a sedimentary drift to a

more and more marine pole, up to the Oxfordian. During this retrogradation, abundant and thick sandy

intercalations up to the Bathonian, become scarcer and thin in younger levels until their disappearance.

From the Kimmeridgian onwards, the sedimentary dynamic is inversed with typically prograding

shallow bioclastic and corallian limestone deposits, as in Europe.

Lowstand system tracts are documented by the regressive intervals of formations: Inmar (late

Toarcian ? - Aalenian), Safa (early Bathonian), Karmon (late Bathonian) and Nahar Sa’ar (late

Oxfordian).

Highstand system tracts are found primeraly in the more proximal Negev-Sinai area: top Ardon

(Toarcian), top Qeren (Aalenian). top Daya (Bajocian). middle Sherif (early late Bathonian), intra-Zohar

(early late Callovian) and top Matmor (late Callovian). Such conditions occur over the entire region at

top of the lower member of the Nahar Sa'ar formation (late Oxfordian).

The late Callovian - early Oxfordian highstand system tracts, in the more distal Hermon area, shows

evidence for connection with the pelagic western Neo-Tethys.

Source: MNHN, Paris

JURASSIC OF THE SOUTHERN LEVANT

231

The regional Jurassic cyclic evolution versus global events in the levantine portion of Gondwana

(Fig. 7), starts with post-Triassic period of karst, the result of the early Liassic regional emersion of Haq

et al. (1988) long term sea level-drop upper Absaroka B (UAB 1-2). filled with Mishhor laterites.

?Pliensbachian-Toarcian Ardon evaporites with shallow lagoon and reefoid carbonates, alternating with

deltaic and paralic lower Inmar sands, express the long term rise with minor short term oscillations,

characterizing the end of UAB. Aalenian upper Inmar (Rosh Pinna) elastics abruptly set in with the

onset of lower Zuni-A -1 sea-level drop and subsequent rise, reaching a significant highstand in the

Bajocian Daya transgression (Laeviuscula -Otoites) and following characteristic Ermoceras and Eligmus

assemblages, ending in Parkinsoni - Thambites lowstand, persisting into the early Bathonian. The early

Bathonian lower Sherif / Safa sands and paralic coals seem to be either delineating a regression, which

in terms of Haq et al. (1988) global cycles is contradictory. This tectono-eustatic event appears to be

characteristic of the entire Levantine - Arabian platform, witnessing a local epirogenetic pulse (S)

(HlRSCH, 1987, 1988).

Fig. 7.— Schematic diagram of Jurassic formations with tectono-eustatic curve. Hiatus (vertical lines), unconformities

(undulated), lateral facies-change (zigzag lines), mainly clastic facies (dots), shales (horizontal lines), mostly carbonade

(white). Tectono-eustatic curve and second order supercycles (Haq el al., 1988).

Fig. 7.— Diagramme schematique des formations jurassiques el courbe tectono-eustatique. Hiatus (lignes verlicales),

discontinuites (ondulee). variations laterales de facies (ligne en zigzag), facies claslique dominant (points), shales

(lignes horizontales), predominance carbonatee (blanc). Courbe tectono-eustatique et supercycles de second ordre

d’apres HAQ et rdf1988).

Follows the LZA-2.2 initial Bathonian phase of drowning (lower Kehailia) with ammonites

(Micromphalites ) in Israel and Arabia and the late Bathonian - early Callovian rise (LZA-3) with

Bullatimorphites (upper Kehailia) According to the chart of HAQ et al. (1988), the late Bathonian is a

lowstand, followed by an overall transgressive early Callovian.

The middle and upper Callovian reach a regional high, inundating most of the Arabian platform with

typical “Zohar/ Matmor” type carbonates, that yield Nerineacea, foraminifers ( Kurnubia - lineage),

brachiopods and abundant bivalves (Eligmus), mostly related to Ethiopean - Somalian taxa.

232

F. HIRSCH ETAL.

The emersion along the coastal plain of Israel, causing karst-phenomena (BUCHBINDER et al ., 1984)

and the hiatus of a significant part of the Callovian (PICARD & HIRSCH. 1987) is, in the present authors

interpretation, apparently the result of pre-Oxfordian (POX) epirogenic movements.

The early Oxfordian (Mariae Zone) Majdal Shams shale-onlap covered the foregoing hiatus in the

Judean embayment. extending from Maghara (Sinai) to the Hermon, possibly interfingering lateraly with

the Galilee carbonatic type facies.

The late Oxfordian - Kimmeridgian shallowing and progressive regression (Alveosepta jaccardi)

occured in contrast to the global trend of a general sea level rise (LZA-4), generating the emersion of the

Syrian (Mardin) promontory, the development of thick evaporites in Central Arabia and the deposition

of sands and shales from the Negev to north Egypt. Such progressive regression may occur in contrast of

the global trend of a general sea level rise, and conform with the general evolution found in Europe. A

generalized sea level rise, resulting in the extension of marine facies, may rapidly fill the available

space, that due to tenfold sediment- production (biogenic in the present case), produces a shallow

platform, until a regressive facies is reached as the filling up is progressing.

Epirogenic movements obscured the Late Jurassic global regression by juxtaposing “Tithonian"

graben-fillings with emersions, continental deposits and basaltic flows.

Changing ecological and tectono- environmental conditions in the middle eastern Levantine Jurassic

are echoed by the composition of floral and faunal assemblages, endemism and cosmopolitism.

Palaegeographical and environmental evolution to a wide extent match the cycles of HAQ et al. (1988),

although it suggests that Levantine “African-Arabian-Apulian” sea level anomalies, due to “noises”

generated by the Proto-Atlantic opening and southern Neo-Tethys rifting, perturbing the global sea level

record.

ACKNOWLEDGMENTS

We express our thanks to R. ENAY (Lyon) for reading an early draft of the manuscript. We are

indebted to J. Thierry (Dijon) and M. Mouty (Damascus) for reviewing the paper. We very much

appreciated their constructive remarks, which contributed to the improvement of the paper. We thank P.

GROSSMAN for drafting of the figures.

Part of the research was performed in the frame of the Peri-Tethys Program. Partial funding was

provided to H-R Feldman by the National Geographic Society, grants 4739-92 and 5666-96.

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The central High-Atlas (Morocco). Litho- and

chrono-stratigraphic correlations during Jurassic

times between Tinjdad and Tounfite. Origin of

subsidence

Andre POISSONMajid Hadri m , Ahmed Milhi ,2>

Myriam JULIEN 111 & Jean ANDRIEUX

111 Universite Paris-Sud, Orsay Terre. CNRS LP 1748. Bat. 504, F-91405 Orsay Cedex, France

u Ministere de CEnergie et des Mines, Division Geologie, Departement Geologie Generate, Rabat Agdal. Maroc

ABSTRACT

At the NW margin of the African craton the High-Atlas belt results from compressional tectonic events which took place

during Tertiary times. The high elevation (which could reach 4160 m), and thrust faults resulted from these events. The initial

extensional basins are part of the transfer zone between Atlantic Ocean and the eastern Mediterranean Neotethys which are

opening during Early Mesozoic times. Coming from the east, the first marine flooding occured in early Liassic times and it

suddenly covered all the High-Atlas domain. Shallow marine carbonates were deposited as the area was subsiding after an

initial rifting phase, characterized by magmatism (Late Trias-earliest Lias). The Liassic epoch can be subdivided into two

periods: early to middle Lias with strong subsidence (syn-rift) and late Lias with renewed subsidence. Extensional tectonic

activity persisted while the whole basin continued to subside: the initial platform was broken so that during Liassic and early

Dogger residual platforms and basins coexisted. In the central High-Atlas a wide platform persisted to the south while in the

middle and northern parts narrow remnant-platforms separated elongated basins. A model of tilted blocks could explain the

persistance of relatively shallow areas which represent the crests of the tilted blocks. Platforms remained shallow marine while

basins became deeper, especially during the Toarcian and early Bajocian times. At the end of the Bajocian the sea began to

retreat and deposits were characterized by shallow marine terrigenous detritics and carbonates. However, high rate of

subsidence persisted, exactly compensated by sedimentary supply. Two curves of subsidence history are given as preliminary

curves for the southernmost platform and the adjacent basin. They point out the tw'o main stages of evolution with two maxima

of subsidence (early-middle Lias and Toarcian to early Bajocian).

Poisson, A., Hadri, M.. Milhi, A.. Julien, M. & ANDRIEUX, J.. 1998. — The central High-Atlas (Morocco). Litho- and

chrono-stratigraphic correlations during Jurassic times between Tinjdad and Tounfite. Origin of subsidence. In: S. Crasquin-

Soleau& E. Barrier (eds), Peri-Tethys Memoir 4: epicratonic basins of Peri-Tethyan platforms. Mem. Miis. natn. Hist. not..

179 : 237-256. Paris ISBN : 2-85653-518-4.

Source: MNHN, Paris

238

ANDRE POISSON ETAL.

RESUME

Le Haut-Atlas central (Maroc). Correlations litho- et chrono-stratigraphiques pendant le Jurassique entre Tinjdad

et Tounfite. Origine de la subsidence.

A la marge NW du craton africain, la chame du Haul-Alias est le resultat devenements tectoniques compressifs qui se sont

produits pendanl le Tertiaire. Cette tectonique est responsable de la haute elevation de la chaine (elle peut atteindre 4160 m).

ainsi que des structures chevauchantes. Les bassins extensifs initiaux, qui se sont ouverts au debut du Mesozoique, font partie

de la zone de transfer! entre I'Ocean Atlantique et la Neotethys de Mediterranee orientale. Venant de Test la premiere invasion

marine s'est produite au Lias inferieur et a recouvert tres rapidement tout le domaine du Haut-Atlas. Apres la phase de rifting

initial caracterisee par du magmatisme (fin Trias-debut Lias), la region reste subsidente et est recouverte de depots carbonates

marins peu profonds. Deux periodes peuvent etre distinguees pendant le Lias : une periode syn-rift avec forte subsidence au

Lias inferieur et moyen. et une periode qui commence au Lias superieur avec une reprise de la subsidence. La tectonique en

extension accompagne la subsidence et la plate-forme initiale est fracturee de telle sorte que pendant le Lias et le debut du

Dogger des plates-formes residuelles et des bassins coexistent. Dans le Haut-Atlas central, une vaste plate-forme persiste au sud

alors que dans le centre et au nord ce sont des plates-formes residuelles etroites qui separcnt des bassins allonges. Un modele en

blocs bascules peut rendre compte de la persistance de zones hautes qui peuvent representer la Crete des blocs bascules. Pendant

le Toarcien et jusqu'au Bajocien inferieur. les plates-formes persistent pendant que les bassins adjacents deviennent plus

profonds. A la fin du Bajocien. la mer commence a regresser et les depots deviennent peu profonds, terrigenes el carbonates.

Cependant la subsidence reste forte tout juste compensee par la sedimentation. Deux courbes de subsidence, encore

preliminaires, sont donnees a litre d'exemples pour la plate-forme sud et le bassin adjacent situe juste au nord de cette plate-

forme. Ces courbes mettent en evidence les deux stades devolution avec les deux maxima de subsidence (Lias inferieur et

moyen, et Toarcien a Bajocien inferieur).

INTRODUCTION

The High-Atlas represents the NW part of the Peri-Tethyan epicratonic domain in Africa. This

domain is an intracontinental fold belt which evolved from subsiding basins (since Triassic times), at the

boundary between the stable Saharan platform and the Moroccan hercynian belt (Figs 1 and 2). The

tectonic inversion responsible of the orogenic system is mainly Tertiary in age (along its northern and

southern flanks, Cenozoic sequences are involved in the fold and thrust belt). The elevation of the belt

reaches 4160 m to the west and 3750 m to the east and the amount of shortening is variable. It is

maximum along the north and south margins where it could attain 50% in the Mesozoic formations

(between Tinjdad and Alt Hani. HADRI, 1993) (Fig. 2). Within the belt itself it is moderate (5 to 10%).

The main prominent tectonic lines are presently thrust faults, responsible for the thickening and

elevation of the belt. Along the northern and southern margins the thrusts are generally very low angle

thrust faults which could represent the flat of ramps which are suspected to have been derived from

normal faults. As a result the restauration of transverse sections at the time of the initial rifting is not so

easy and is highly dependant on the model which is considered. All the models insist on the role played

by the inherited hercynian structural directions on the Triassic rifting. The Late Hercynian faults, a

northeastward prolongation of the Tizi n'Test fault zone, have a NE-SW strike. They have been

reactivated during this initial rifting and lava flows and red thick terrigenous deposits accumulated in

fault-controlled graben. Laville'S model (1981), points out the role of strike slip faults in the initiation

of the depot centers as pull apart basins, while other models favoured another style of deformation

mainly extensional (WARME, 1988). Extension-transtension is probably a good explanation.

The investigated area is located in the central High-Atlas between Tinerhir, Tounfite, Rich and

Tinjdad (Fig. 1). Previous works have provided good data (BERNASCON1, 1983; FADIL, 1987; STUDER

1987; MlLHI. 1992; Hadri, 1993). In this area the High-Atlas attains its maximum width and is sited on

a Palaeozoic basement which has been folded and faulted during Hercynian times. Coming from the NE,

from the Mediterranean Neotethys, the initial transgression occured in early Liassic times and, as a

result, the Hooded area acquired its general appearance of a NE-SW elongated gutter. This morphology

was preserved all along Jurassic times (CHOUBERT & FAURE-MURET. 1962; DUBAR. 1962). The first

marine deposits consisted of shallow marine carbonates, but, as early as the late Sinemurian

(Lotharingian), more deep sediments appeared in the central part of the basin, not everywhere but in

elongated small troughs separated by narrow platforms which remained the site of shallow carbonate

deposits with coral reefs (Du DRESNAY, 1977). These narrow platforms have been interpreted either as

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

239

anticlines or as tilted blocs, depending on the models, and their origin remains under discussion. A large

variety of facies resulted from such contrasted morphologies.

This paper is an attemp to reconstruct the palaeoenvironments of the Central High Atlas during

Jurassic times along a N-S geotraverse from the Moulouya high to the North to the African craton to the

South. This area is representative of the various types of palaeoenvironments which can be found all

along the belt and could be used for further correlations at the scale of the entire High Atlas. In this area

a transition between the platform carbonates and the deepest basinal facies can be observed. So we are

able to present an emended review of the classical formations previously described. We hope our

attempt will help to clarify rather confuse nomenclature. We shall discuss the question of the origin of

the subsidence. This contribution concerns a part of the investigations which are going to be extended to

the entire Morocco.

Fig. ].— Location of the studied area and of the NW-SE cross section of figure 2.

Fig. I.— Carle de localisation de la region etudiee el de la coupe de la figure 2.

THE CENTRAL HIGH-ATLAS. A N-S TRANSECT BETWEEN MOULOUYA

HIGH AND ANTI-ATLAS BELT (Fig. 1)

LlTHOSTRATIGRAPHY AND BIOSTRATIGRAPHY

We have focused at first on lithostratigraphy and chronology in order to constrain palaeogeography

and palaeoenvironments. As a result of eustatic sea level fluctuations, and local tectonic events, Liassic

and Dogger times can be subdivided into 3 periods, each of them being characterized by different

palaeoenvironments and facies: initial marine flooding (Hettangian-Sinemurian), formation and

deepening of basins in the northern half part of the initial platform (Lotharingian-Bajocian), and retreat

of the sea and emergence (Bajocian-Bathonian).

240

ANDRE POISSON ETAL.

NW SE

Fig. 2.— General NW-SE cross section of the central High-Atlas. This section crosses the central High-Atlas from the

Marrakech-Tadla plain to the NW to the Ouarzazate basin to the SE, and it represents a tentative interpretation of the

deep structures below the High-Atlas belt. It is only based on surface data (Fadil, 1987; Hadri, 1993, reinterpreted and

recent field data), but it takes into acount another section located to the west (Errarhaoui, 1998), and which is more

documented, especially for the Palaeozoic. The gabbroic boddies are a specificity of this section. Their roots have not

been interpreted. They have been affected by the atlasic tectonic, and they probably have been translated from their

primitive emplacement. Their origin and their mode of emplacement are hardly discussed (wrench faults or diapirs?).

The rate of shortening is very important to the SE extremity of the section. It seems less important in the central pan of

the belt where it cannot be precisely estimated. It became again obviously more important to the NW. Cr: Cretaceous;

Bath: Bathonian; Baj: Bajocian: Aal: Aalenian; Ll-3: early to late Lias; L2r: middle Lias with coral reefs; Lid:

Sinemurian, dolomitic; Tr: Trias; P: Palaeozoic.

Fig. 2.— Coupe generate NW-SE du Haul-Atlas central. Cette coupe traverse le Haul-Atlas depuis la depression de

Marrakech-Tadla au NW jttsqu'au bassin de Ouarzazate au SE. Elle presente une interpretation de la structure

profonde sous le Haul-Atlas d'apres les donnees de surface ( Fadil. 1987 ; Hadri, 1993). reinterpretees d'apres des

donnees de terrain recentes. Le Paleozoi'que affleure peu et sa strucuture est interpretee d'apres une coupe mieux

documentee situee plus a I'ouest (Errarhaoui 1998). Les corps gabbro'iques sont une specificite de cette coupe. Leurs

racines n'ont pas etc interpretees. Ils ont ete affectes par la tectonique atlasique et its ont probablement ete deplaces

par rapport d leur position primitive. Leur origine et mode de inise en place sont Ires disputes (failles decrochantes ou

diapirs ?). Le taux de raccourciSsement est ties important d I'extremite SE de la coupe. II semble moins important dans

la partie centrale mais it ne pent pas y etre estime avec precision. II redevient plus important au NW. Cr : Cretace ;

Bath: Bathonien : Baj : Bajocien : Aal: Aalenien ; Ll-3 : Lias inferieur d superieur ; L2r : Lias moyen recifal; Lid :

Sinemurien dolomitique ; Tr : Trias : P : Paleozoi'que.

Concerning lithostratigraphy many formations have been previously described in a lot of papers since

half a century. Some of these formations are of local interest, many others are synonymous in term of

palaeoenvironments. In order to clarify this nomenclature we have selected a transect located in the

central part ol the High-Atlas where both platforms and basins are well represented. Along this transect

we have distinguished in between the formations which are widely distributed in the High-Atlas and the

formations which are related to local specific environments and which grade lateraly into formations of

more general scope. These formations are presented in two chronological charts along two orthogonal

profiles (Figs 3 and 4):

— the N-S one (Fig. 3), shows the platform-basin transition in a direction perpendicular to the axis of

the basin (from one margin to the opposite one).

— the other, WSW - ENE (Fig. 4), shows the same platform-basin transition along the axis of a basin

bordering the southern platform of the High-Atlas.

The succession of formations presented on Figs 3 and 4 reflects the evolution of the

palaeoenvironmental conditions during Jurassic times since the Sinemurian up to the Bathonian. The

Late Jurassic has not been identified along this transect however it could be included in the red

formations which have been classically attributed to the Bathonian and infra-Cenomanian. At the bottom

of the sequence, red fine-grained detritic formations with evaporitic layers and basaltic lava flows are

essentially Triassic to Hettangian in age according to K/Ar dating (210 to 196 Ma), but they could reach

the Sinemurian (Laville & HARMAND 1982).

The initial marine flooding (Hettangian-Sinemurian)

The main formations which have been previously described: Idikel (STUDER. 1987), Agoulzi (MlLHI,

1992) and Ait Ras (LEMARREC & JENNY, 1980; JENNY, 1988), are synonymous. They represent the

first carbonate layers overlying the Palaeozoic basement or the Triassic beds. They are composed of

Source: MNHN, Paris

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

241

shallow marine carbonates more or less dolomitized which have been described by BURGESS & LEE

(1978), and SEPTFONTAINE (1985). The main facies are pisolitic dolomudstones with fenestral fabric

and mud cracks, evaporites and algal laminated boundstones. The palaeoenvironments are those of an

internal platform more or even more restricted (intertidal to supra-tidal or sebkha). The age of these

formations is poorly constrained in most places. They have been attributed to Hettangian and

Sinemurian. They seem to have suddenly covered the entire central and eastern High-Atlas domain,

from east to west, possibly by rupture of a natural dam. Faulting was probably active at that time but it is

not evident on the field. This period corresponds to a general sea level rise (Fig. 5). We shall see below

that the thicknesses vary from one place to another and that subsidence curve show a prominent first

maxima.

N S

◄- TOUNFITE TINUDAD-►

1 Okm

- -

• • • • «

• • • •

W7?.

Evaporites

R6?ifs

□Critique greseux

Marnes

Conglomerate

Emerge

Fig. 3.— Chronological chart of the formations along a N-S section through the central High-Atlas.

Fig. 3 .— Charte chronologique des formations le long d'une transversale N-S d trovers le Haut-Atlas.

w-sw

◄-AITHANI

E-NE

RICH-►

BATHONIAN

Anemzi

BATHONIAN

‘=

Assn ii

1 ’

BAJOCIAN

AVt ">

A s s o u 1 1

\ upper Agoudim

BAJOCIAN

AALENIAN

T'Hani 1 \\

. / J , 1 < '

Amellago.

AALENIAN

TOARCIAN

Adoumn^

lower

Agoudim (AGI) —■_

TOARCIAN

DOMERIAN

CARIXIAN

Aganane

«.'houcht^P

u u c n d i s

Amanjoune —

- - - _

—Aberdouz- -

LOTHARINGIAf^

R a t

v s I ohdra

- -j--

LOTHARINGIAN

SINEMURIAN

Alt Ras

A g o u 1 z i

I d i k e 1

SINEMURIAN

1 Okm

-CUP’

• • • •

Evaporites

Remits

oetritique greseux

Marnes

Conglomerate

Emerge

Fig. 4.— Chronological chart of the formations along a WSW-ENE section near the southern High-Atlas platform.

Fig. 4 .— Cliarte chronologique des formations le long d'une section WNW-ESE d la bordure de la plate-forme sttd du Haul-

Atlas.

Source

242

ANDRE POISSON ETAL.

+ 0 _

PORTLANDIAN

KIMMFRIfY^IAM

141

•<

OXFORDIAN

J3-1

CALLOVIAN

J2-3

- 156 -

149

<zi

C/3

BATHONIAN

J2-2

BAJOCIAN

J2-1

165

AALENIAN

174

TOARCIAN

J1-2

PLIENSBACHIAN

182

SINEMURIAN

J1-1

- 189 -

HETTANGIAN

FR3-2

C/3

RHAETIAN

NORIAN

— 200

Fig. 5. Globa! cycles ol relative change of sea level during Jurassic (after Haq el al, 1988).

Fig. 5.— Cycles globaux des changements relatifs du niveau des mers (d'apres Haq et al.. 1988).

The SECOND PERIOD: coexistence of platforms and basins (Lotharingian-Bajocian)

As a result of the continuation of the rifting processes, the initial platform was broken and elongated

basins developed in its central part during late Sinemurian (Lotharingian). Unlike the models generally

ad mi ted which present the central part ot the High-Atlas as a single deep basin, there were several

basins, separated by shoals which could be the top of tilted blocks in a model of extensional tectonics.

I hese higher parts could have been more or less deeply submerged and as a result they could have been

the site ol either a shallow marine carbonate deposits (remnant-platforms with coral reefs), or hemi-

pelagic marls and carbonate deposits.

The basinal formations

,A 4 EARL yrvoo D MIDDLE LlASSIC TIMES.— The following formations, Aberdouz (STUDER, 1987), Todrha

(MILH! 1992) and Amanjoun (Hadri. 1993), correspond to the first basinal deposits in the central part

ot the High-Atlas along the main northern and southern platforms but also around the small narrow

remnant-platforms. They are restricted to the elongated basins developped as a graben system. The

tiansition between shallow marine and basinal deposits may be progressive though very fast, but

sometimes the contact is abrupt and looks like a fault (Fig. 6). Slumps are frequent at a short ditance of

the platform (Figs 6 and 7). The main facies are dark coloured cherty limestones with sponge spicules

and sponge build-ups which look like reefs. Near Ait Hani these sponge reefs are interstratified in the

ammonite bearing limestones which could reach the Carixian. Such reefs are not resedimented blocks as

hey are undoubtedly at their living emplacement (Fig. 8). Warme (1988) reported such build ups as

typical facies of the central part ot the High-Atlas trough to the north of Rich. Nevertheless they are not

restricted to the central part of the basin. They have actually been observed in other places where they

seem to preceed coral reefs along the platform margin (MlLHI, 1993). Otherwise, in general, they seem

to characterize environments deeper than shallow platforms and they could be used as a good marker of

he mitmnon o subsidence in the whole High-Atlas. Nevertheless the sponge reefs have not yet been

studied in detail in the High-Atlas. They have been observed in rather different depositional sequences

and we are not able to conclude about their living environment (unique or diversified and at which depth

™ S . ea 'f vel th fy we u re llv ‘ n g durin g L ‘assic times). In the elongated basins cherty limestones are

surrounded by marls with resedimented blocks near the platforms (frequently these blocks are coral reef

Source: MNHN, Paris

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

243

Fig. 6.— Southern platform of the High-Atlas. Road between Goulmina and Amellago. Abrupt of the plaform margin

suggesting the morphology of a fault cutting through the Jbel Ikis coral reef (R). (Ps: palaeoslope of the reef; Jbel

Choucht formation). The right half part of the picture (A) corresponds to the basinal limestones onlaping the platform

with, from bottom to top . Aberdouz and Ouchbis Formations (early and middle Liassic). Faulting occured probably

during Lotharingian time. Notice the mega-slumps near the palaeoslope (see also figure 7; after Hadri, 1993).

FlG. 6 .— Plate-forme sueI du Haul-Alias. Piste entre Goulmina el Amellago. Bordure de la plate-forme avec abrupt, pouvant

correspondre d line faille, en limite nord du recif d'lkis (R> ; Ps : paleo-pente du recif, formation du Jbel Choucht. En

avant du recif (moitie droite de la photo) (A), les calcaires a ammonites (facies de bassin). du Lias inferieur d moyen

(formations d'Aberdouz et d'Ouchbis) viennent recouvrir progressivement la paleo-pente. II y a eu effondrement de la

plate-forme probablement au cours du Lotharingien. Remarquer les mega-glissements de bancs sur la petite

sedimentaire (voir egalement la figure 7: d'apres Hadri, 1993).

limestones), and turbidites. Ammonites are locally abundant and provided good stratigraphic data. Rates

of subsidence are important and will be discussed below.

TOARCIAN TO BaJOCIAN.— At the end of the Domerian and during the middle Toarcian a significant

eustatic rise of sea level occured (Fig. 5), which is approximately contemporaneous in the High-Atlas

with a new tectonic event which is not only the reactivation of older faults. The platforms, which

correspond to the footwall of reactivated normal faults, were again upheaved. As a result of these

antagonist events: rise of sea level and tectonic uplift and compression, the shallow platforms came to

near (or complete) emergence, while the basins in general became more subsident. A general

discontinuity and local angular unconformities resulted from these events. Erosion on lands provided

detritals such that sedimentation in basins became more terrigenous with marls and subordinate

sandstones. In more detail, the general morphology of the basinal domain is affected by the persistance

of a tectonic instability through the Toarcian: some highs were submerged and were the site of deposits

in progressive unconformity along the flanks of the antiformal ridges (Fig. 9), and in complete

unconformity on the top of these ridges, while some other came to emergence. STUDER & Du DRESNAY

244

ANDRE POISSON ETAL.

F ' G ' S ,°"o ern ?‘ atf ? rm T ° f ' he Hi | h - A,la ^ Road belween Goulmina and Amellago. Aberdouz limestones with

a large slump at a regional scale. Thickness here is 10 m.

F ' G - SU f d “ Hau '- A '^ (Piste entre Goulmina e, Amellago). Figure de glissement d'echelle

tegionale (10 m d epcusseiu sur la photo), dans les calcaires de la formation d'Aberdouz-

(1980) described such unconformity at the western end of Jbel Masker. There an E-W striking antiform

has been eroded during the Bajocian. It is suggested that this antiform existed as early as early Toarcian

as an anticline ride , which was the site of a relatively condensed sedimentation.

Similar evolution seems to have prevailed during Aalenian and early to middle Bajocian times. High

lew ot ^; cu ™ ulatl ° n characterize some areas located to the northern half of the atlasic domain: Imilchil

(MV ot 1 lrrhist). lounhte and NE of Rich (lower and upper Agoudim formations (STUDER, 1987)

which grade laterally into Amellago and Assoul 1 formations of HADRI (1993); these later represent the

Source: MNHN. Paris

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

245

Lotharingian

Domerian-Carixian

ocian

Toarcian

Fig. 8.— Basinal sequence in the region of Assoul. Aberdouz-Amanjoun formation (Lotharingian-Carixian): cherty bedded

limestones with sponge reefs (R). Ouchbis formation (Carixian-Domerian): bedded limestones with ammonites.

Agoudim formation (Toarcian): marly limestones and marls with ammonites. Amellago formation (Aalenian-Bajocian):

oobioclastic limestones caped by the “calcaires corniehes" which include small coral reefs.

Fig. 8 .— Serie cle bassin dans la region d'Assoul. Formation d'Aberdouz-Amanjoun (Lotharingien-Carixien): calcaires lites a

silex avec recifs a eponges (R). Formation d'Ouchbis (Carixien-Domerien) : calcaires lites a ammonites. Formation

d'Agoudim <Toarcien) : calcaires marneux et marnes d ammonites. Formation d'Amellago (Aalenien-Bajocien) :

calcaires oobioclastiques avec la bane des “calcaires corniehes" au sommet a petits recifs de coranx.

transitional terms between platform and basin). The maximum being reached during the Bajocian just

before the retreat of the sea. Bathonian times are characterized by continental deposits all over the High-

Atlas but with important discrepancies concerning thicknesses from one place to another. Nevertheless

thicknesses are not always well known due to present day poor chronological data. Investigations are

going on.

THE PLATFORM DEPOSITS

EARLY to middle LIASSIC TIMES.— As a result of the formation of basins, the platform areas were

considerably reduced in width during the Lotharingian. but they prograded northward during the middle

Lias. The more important areas where shallow marine deposits persisted during that time are located to

the west and along the margins of the High-Atlas, essentially along the southern margin (Figs 9 and 10).

In these areas some major formations have been described. Their validity at the scale of the whole High-

Atlas is recognized. It is the case for the following formations: Jbel Choucht (SEPTFONTAINE, 1985)

(outer platform: bioclastic and oolithic sands with coral reef build up along the platform margin), Jbel

Rat (JENNY. 1988), which corresponds to the inner supra-tidal platform (dolomitized algal laminated

limestones, dolomudstones with bird-eyes; tepee structures are frequent). Aganane (SEPTFONTAINE.

1985) (shallow marine inner platform, carbonates with benthic foraminifera and giant pelecypods)

(Fig. 1 1). Some other formations are more local but they could represent an original environment. This

is the case for the Aghbalou formation (HADRI, 1993), which corresponds to an evaporitic sequence

deposited in two subsiding sebkha areas (mainly gypsum and anhydrite, 200 to 500 m in thickness), and

which could be considered as a special facies into the Aganane formation. These areas are located on

both side of the Goulmina fault. Compared to the basin ones the thicknesses ot the platlorm sequences

are reduced, although they are not uniform. Along the southern margin ot the High-Atlas, especially

from the Dades valley to the eastern High-Atlas, the basinal area was reduced in width during the middle

Lias due to the progradation of the carbonate outer shelf with coral reefs (MlLHI, 1992; HADRI, 1993).

Source:

246 ANDRE POISSON ETAL.

Fig. 9.— Southern platform of the High-Atlas to the north of Tinjdad. Northern margin of the Aaddani coral reef. To the left

(just outside of the picture), the reef is caped by the Azilal formation (Toarcian, shallow marine facies). To the left side

of the picture the basinal early Toarcian marls (Agoudim formation) have covered an abrupt morphology (100 m high)

which suggests a fault (pre-Toarcian).

l ie. 9. Plate-forme sud dit Haul-Atlas ait nord de Tinjdad. Bordure nord du recif dAaddani. Abrupt correspondant

probablement a une faille ante-Toarcien. Au sommet du recif (vers la gauche, en dehors de la photo), le Toarcien est de

facies Azilal (plate-forme), alors qu'au pied du recif (a droite). il est de facies bassin (formation d Agoudim). monies a

ammonites contenant des blocs recifaux resedimentes.

As a result, during the Lotharingian the southern platform margin was located just to the north of

Errachtdia, while during Carixian and Domerian times it was located to Foum Zabel (tunnel du

Legionnaire), several kilometres to the north.

TOARCIAN TO BAJOCIAN.— During this period, the platforms were the site of important change in

rate and type of sedimentation. Despite the eustatic sea level rise, some areas came to emergence and

Source: MNHN, Paris

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

247

Fig. 10.— Southern platform of the High-Atlas near Aghbalou n’Kerdous (to the north of Tinjdad). Aghbalou formation

(Carixian): sequence with gypsum of sebkha type. Aganane formation (Carixian-Domerian): dolomitized limestones

with giant pelccypod “reefs" (1), and coral reefs (2). Azilal formation (Toarcian): red shales and marls with small patch

reefs and bioclastic limestones.

Fig. 10.— Plate-forme sud du Haut-Atlas a Aghbalou n'Kerdous (au nord de Tinjdad). Formation d‘Aghbalou (Carixien): serie

gypseuse de sebkha. Formation d'Aganane (Carixien-Domerien) : calcaires dolomitiques avec “recifs" d grands

lamellibranches (I), el recifs a coraux (2). Formation d'Azilal (Toarcien): marnes silteuses rouges avec petits recifs de

coraux et calcaires bioclastiques.

were eroded. In some other places crusts developed and open diaclases were filled by detritus and

mineralisations, hard grounds are frequent. They correspond to a gap: the early Toarcian (in part or in

totality), could be missing. This discontinuity is widely distributed in the High-Atlas and represents the

boundary between two main sequences of deposition. DU DRESNAY (1964) and SADKI (1992), following

previous authors, pointed out such discontinuity in various places in the High-Atlas and they correlated

it with a middle Toarcian transgression (approximately coeval with the eustatic sea level rise).

Nevertheless, the existence of angular unconformities below the Toarcian. and more generally below the

Dogger, have to be correlated with compressional events which are simply registered in the platforms by

gap and discontinuities, and are essentially recognized in the basinal areas as depicted above. The Azilal

formation (JENNY. 1988) has been described in the western termination of the High-Atlas. It corresponds

to continental and intertidal deposits (red terrigenous clays, sands and conglomerates including patch

reefs towards the sea). In the Ait Hani area, in the central part of our transect here, the Aft Hani

formation (HADRI, 1993) represents the upper part of the Azilal formation. It is composed of shallow

marine to intertidal carbonates with coral patch reefs. Terrigenous sediments are subordinate. The

Source:

248

ANDRE POISSON ETAL.

Amellago formation (Hadri, 1993) is the lateral equivalent of Ait Hani towards the open sea to the east

(Fig. 4), and is composed of prograding bodies of oobioclastic sands. These sands are expelled from the

adjacent platforms such as Ait Hani, and they correspond to a new development stage during which the

basinal areas were contracting. During late Aalenian and Bajocian shallow marine areas predominate

and progressively replaced the deeper areas which retreated to the east. As we shall see below these

events remain difficult to explain.

Fig. 11.— Example of a bed of giant pelecypods in life position. Aganane formation.

FlG. 11 .— Exemple de bancs a grands pelecypodes en position de vie. Formation d'Aganane.

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

249

The third period: retreat of the sea and emergence (late Bajocian-Bathonian)

At the beginning of this period shallow marine areas predominate and the sea progressively retreats

towards the east. The general shallowing upwards sequences are capped by continental deposits during

the Bathonian which marks the end of the Liassic-Dogger major cycle in the High-Atlas.

Subsidence AND EUSTATIC SEA LEVEL CHANGE (Figs 12, 13, 14)

Age (Ma)

During Liassic and Dogger times sea level curve shows a first maxima during the Lotharingian-early

Carixian, followed by a small drop during the Carixian, and a second maxima (more important), during

the Toarcian (Fig. 5). In the Central High-Atlas the main discontinuities are: 1- the initiation of the

basins by drowning of the preexisting platforms (during Late Sinemurian and thus just before the first

maxima). This period is characterized by quite purely extensional tectonic events. It can be considered

as syn-rift (s.s.) 2- the renewed deepening of these basins which took place during early (?)-middle

Toarcian is coeval with the second maxima. This

period is also characterized by extensional

tectonic events especially in the platform areas

(north and south; under preparation), but also by

compressional event in the axial part of the belt.

So, on a wide scope, the sea level rise is though

not to be responsible for the formation of the

basins nevertheless provoked an increase of their

depth. As a result, subsidence itself may not be

directly correlated with the sealevel curve. In fact

it varies considerably from place to place and is

thus related to tectonic events. The discussion

concerns the precise nature of these tectonic

events.

Important variations in thicknesses have been

reported and correlated with subsidence. Table 1

give some data (non decompacted sediments) for

the central High-Atlas along a N-S profile

(Tinjdad-Tounfite) (data from STUDER, 1987 &

Hadri, 1993). From these data two subsidence

curve have been prepared. They are given here as

preliminary curves, one for the southern platform

(Iffer section. Figs 12 and 13), and the other one

for a basinal area in the region of Assoul

(Fig. 14). The data (Table 1), suggest the

following remarks:

— the northern and southern platforms

present similar thicknesses during Sinemurian. In

the wide southern platform two relatively

subsiding areas developed during Middle Liassic

time. They were the site of evaporitic deposits:

Aghbalou basin, 200 m (Hadri, 1993), and

Errachidia basin, 500m for the evaporites only

(JOSSEN & Filali-Moutel 1992). This later is

essentially known in holes drilled for oil, water

and coal prospection;

— the central area was, at the same time the

site of an active subsidence. At first (early?-

middle Sinemurian), the subsidence rate was

compensated by the sediment supply. The facies

Fig. 12.— Subsidence history for the section of Iffer

(southernmost platform).

FIG. 12 .— Hisioire de la subsidence pour la section d'lffer

(bordure sud de la plate-forme meridionale du Haut-

Atlas).

Fig. 13.— Subsidence rates for the section of Iffer.

Fig. 13 .— Variation des taux de subsidence au coins du

Jurassique pour la coupe d'lffer.

Source:

250

ANDRE POISSON ETAL.

Age (Ma)

Fig. 14.— Subsidence history for a section (near Assoul).

which corresponds to a basinal area to the south of the

transect studied here.

Fig. 14.— Histoire de la subsidence pour line coupe (au SE

d'Assoul) correspondent a une zone de bassin.

were the same on the platforms and in the central

area but they were thicker at the emplacement of

the future basin (600 m instead of 400 m).

Subsidence remained active and rate of

sedimentation increased considerably, and

rapidly during the Lotharingian: the Aberdouz

and Amanjoun formations reaches 1000 m. As

sediment supply did not compensate the

deepening of the basin, consequently, facies

changed from shallow marine to hemipelagic;

— subsidence remained active in the central

area during Liassic and Dogger times but not

everywhere at the same rate: the depocenters

moved during this period. They were localized at

first in the southern part of this area during

Liassic times and they migrated northwards

during the early Dogger. In such a context of

local variations in thicknesses subsidence history

would have to be considered from one

depocenter to another one, in order to retrace the

variations in the rate of subsidence. This work,

under preparation, require specific detailed data

which are not always available in the published

works.

Table I.— Variation in thicknesses in the central High-Atlas. Thicknesses in metres. Non decompacted.

Tableau Variations depaisseur des formations dans le Haul-Atlas central. Epaisseurs en metres. Non decompacte.

Southern platform

(Tounfite)

Central aera

Southern

platform

(Tinjdad)

BATHONIAN

Anemzi 800-1000

Ait Hani 200

BAJOCIAN

Agoudim

AG II 2000-5000

AALENIAN

Agoudim

AGI 0-700

170

Ait Hani 200 — 850 Amellago

TOARCIAN

Tagoudite 200 .

Amellago 800

Amanjoun 750

Iffer 0-60

DOMERIAN

CARIXIAN

200

Masker (E) 1000 N

Aberdouz

Amagour 50 S

200-500

(evaporites)

SINEMURIAN

Idikel 350

Aberdouz 800

Amanjoun 1000

Iffer 400

The subsidence curves clearly point out. both on platform and basin, the existence of the two separate

events which have been depicted above: the first during the Sinemurian and the second during Toarcian-

Aalenian times. The first can be considered as syn-rift, but the second is not clearly post-rift.

Source:

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

251

During the Sinemurian (and more precisely during the late Sinemurian i.e. the Lotharingian), the

initiation of several small basins is associated with a very rapid change of facies. Sometimes Aberdouz

deposits lie against cliffs which are probably ancient fault planes. In such a case the change of facies

from shallow marine to hemipelagic can be precisely refered to faulting. This seems to be the case in

many places during the late Sinemurian, especially along the southern margin of the High-Atlas, even if

the faults are not always observed. A model with extensional faults (Figs 9 and 10), could explain the

rapid initiation of these basins as well as the sudden facies changes. The existence of NE-SW strike slip

faults during this period has not been confirmed by detailed recent studies (EL KOCHR1 & CHOROWICZ,

1996, and our data under preparation). The NW-SE faults, such as the fault to the north of Goulmina

(Eig. 10), could be interpreted as transfer fault in the model of oblique extension proposed by EL

KOCHRI & CHOROWICZ (1996). The same mechanism could have persisted later and could explain the

high rate of subsidence prevailing during middle Liassic times. In conclusion, during early and middle

Liassic times, there are evidences of extensional tectonics. After the Triassic magmatic activity which

accompanies the initial rifting, extensional tectonic remained active during Liassic times, with a first

maxima of subsidence, and the beginning of cooling of the lithosphere.

During Toarcian important changes occur. Globaly, the minor sealevel rise should have provoked a

general transgression and, as a result, a general flooding of the platforms and a deepening of the basins

would have occured. However, at the scale of the Central High-Atlas in general, this was not at all the

case:

— some areas were effectively submerged and open marine deposits transgressed over previous

internal platforms, while other areas (for example in the southern platform), became emergent (or near-

emergent), and Toarcian could be highly condensed (ferruginous crusts), or restricted to about 60 m of

red detritics and shallow marine limestones with patch reefs. Small extensional normal faults have been

observed in these platforms.

— on the contrary, in the basin located just to the north of the southen platform (region to the SW of

Assoul), the same interval of time could be represented by 800 m of marls with calci-turbidites.

It is also the case in the northern part of the High-Atlas, just to the south of the platform. There,

thicknesses vary considerably: from 1250 m to the north (Ouchbis), to 150 m (Jebel Masker, western tip,

on an ancient high), and to 800 m to the south (between Jebel Masker and Jebel Aberdouz) (Studer,

1987). In this area Tagoudite formation (STUDER, 1987), records the erosion of the Moulouya high in

early Toarcian time. To the western tip of Jebel Masker an important angular unconformity has been

observed (STUDER & DU DRESNAY, 1980), which separate the Toarcian and the Bajocian. Thus a

compressional event occured, at least after the Toarcian. We have also oberved such stuctures to the

west and they seem to characterize the axial part of the High-Atlas. They have been correlated with the

emplacement of magmatic bodies (Laville & HARMAND, 1982).

In conclusion, during Toarcian time, global sealevel rise did not provoked, in general, the expected

effects of a transgression, and the main change in palaeoenvironments may be related to a renewal of

extensional tectonics, accompanied by the second maxima of subsidence.

During Aalenian strong thickness differences have been reported. For example, early and middle

Aalenian sediments can be completely missing or at least strongly reduced, for instance in Jebel Masker

(western tip), and Jebel Aberdouz. As a result, since Toarcian, Jebel Masker represented a high with no

or reduced sedimentation. On the contrary the basins between Jebel Masker and Jebel Aberdouz, and the

basins to the north of Jebel Masker, were continuously subsiding (1250 m of sediments), in continuation

of the dynamics inherited from Toarcian time.

On the contrary, during late Aalenian and Bajocian times, deposits record a gradual change from

deep water marls, micrites and turbidites, to shallower water deposition ot benthic shell bearing

limestones with coral-algal reefs at the top. This shoaling of the central High-Atlas basins, related to the

filling up of the previous troughs, has been described in the area of Rich (STANLEY, 1981), where the

Agoudim formation is 1200 m thick (900 m of deep basin deposits capped by 300 m of transitional to

shallow marine sediments). Farther to the west, in Jebel Aberdouz, the lower Agoudim formation (deep

marine; 800 m; Toarcian) is overcome by the upper Agoudim formation (shallow marine; 1000 m). In

the basin, between Jebel Masker and Jebel Aberdouz, the deep marine lower Agoudim formation (1250

m) is also overcome by the upper Agoudim (more than 3000 m: shallower to very shallow water). The

252

ANDRE POISSON ETAL.

change from deep to shallow marine conditions seems abrupt in Jebel Aberdouz and is possibly more

transitional in the basin located just to the north. After a sea level fall during Earlv Aalenian. Bajocian

was characterized by new sealevel rise. Thus the Bajocian shoaling of the"High-Atlas sea cannot be

related to global eustatic sealevel change, but has a local origin which is tectonic" Compressional events

have been proposed as an explanation for the formation of anticline ridges, with low sedimentation rate

(Studer, 1987). Although such events can be responsible for the emergence of large areas, however

they cannot explain the subsidence during Bajocian time. According to LAVILLE & HARMAND (1982),

synsedimentary deformations such as progressive unconformities, anticline ridges and gravity slidings',

could have resulted from subvolcanic intrusions in the context of pull-apart basins" However, the

intrusions are not always contemporaneous of the deformation, few of them are Bajocian. the majority

are either Triassic to early Lias, or Bathonian to Late Jurassic and Early Cretaceous. According to

Studer (1987), the emplacement of the intrusions (dykes and large bodies), took place after the

deposition ot the Anemzi formation (which is dated Bathonian), in the area of Tounfite-Rich. Such a

renewal of the magmatic activity followed a renewal of the subsidence and both necessitated extensional

activity. The new faulting reported by Studer (1987), in Jebel Masker could be responsible for the near

emergence of the central part of the High-Atlas.

In conclusion the high rate of subsidence during Bajocian time, has to be associated with extensional

events. Contrarily to the period which ended during Aalenian, emergence preceeded subsidence during

Bajocian and was compensated by sediment supply: the subsidence is progressive, probably

accompanied by a progressive unconformity related to a progressive deformation such as the uplift of a

ridge, and rapid subsidence in the neighbouring areas. In the model of LAVILLE (summarized in

Laville & Fedan, 1989). the reactivation of the E-W trending fault system induced multiple releasing

and restraining stepover strike-slip basins. During Bathonian (Anemzi formation, STUDER 1987)^

subsidence remained very active in some areas (800 to 1000 m of continental deposits), and magmatic

activity developed along older faults. The subsidence history during Aalenian and Bajocian-Bathonian

appears more complicated in the axial part of the High-Atlas belt and would require new field

investigations in order to localize the depot centers and sediment thicknesses fluctuations over the area.

PALINSPASTIC RESTORATION OF SECTIONS FOR LOTHARINGIAN

, _ The pal inspas tic maps (Figs 15 and 16), correspond to the situation during the Sinemurian, and figure

/ presents five N-S restored sections representing the superposed deposits since the early-middle

Sinemurian until the end of the Lotharingian. As a result of field work the restoration is mainly based on

Fig. 15.— Location of the studied

area on a palinspastic map cor¬

responding to the Lotharingian.

1, continental areas: 2, shallow

marine platforms; 3. deepers

basins.

FlG. 15. — Localisation de la region

eludiee sur une carle palin-

spastique correspondant au

Lotharingien. I. zones conii¬

ne males ; 2. plales-formes

marines peu profondes ; 3. bas-

sins.

Source: MNHN, Paris

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

253

, MIDELT

VZZA i

i I 2

Fig. 16.— Palinspastic map showing

the palaeoenvironments during

the Lotharingian. 1, continental

areas; 2, shallow marine

platforms; 3, coral reefs along

the margins of the platforms; 4,

deeper basins.

Ftc. 16 .— Carle palinspastique

montrant les palaeoenvironne-

ments pendant le Lotharingien.

/, zones emergees ; 2, plates-

formes marines ; 3, recifs de

coraux en bordkre des plates-

formes ; 4. bassins plus

profonds.

facies correlations and detailed observation of the transition between shallow marine and basinal

carbonate. In such zones of transition, the rapid lateral change of facies from very shallow platform

carbonates with coral reefs to deeper facies (ammonite bearing mudstones, bioclastic turbidites) is

correlated to contrasted morphologies suggesting the occurrence of faults. In some places, such faults

have been observed (Hadri, 1993). As a result our general interpretation favours a model of tilted blocs

along normal more or less listric faults. The localization and strike of these faults being guided by older

deep seated faults. In this model several elongated semi-graben basins were initiated and as soon as late

Sinemurian, were the site of basinal deposits with ammonites. At the same time the highest part of the

tilted blocks remained in more or less shallow marine conditions: in many places sponge build-ups could

have developped near 200 or 300 m below sea level, while on some other tops corals attest of very

shallow conditions. As a result, during late Sinemurian large shallow marine platform areas only

persisted along the north and south margins of the basin and to its western end. To the south of the

transect this platform remained relatively large: 30 and 60 km respectively to the west and to the east of

the Goulmina fault. At that time it became progressively an internal platform where restricted conditions

prevailed and an outer platform with sparse coral build up and more generally bioclastic sands. These

conditions also prevailed during middle Liassic times when coral reefs attained their maximum

extension (several kilometres in width), and when the internal platform evolved to sebkha conditions. By

contrast the central part of the High-Atlasbasin was characterized by a succession of highs and basins.

These later being the site of an active subsidence.

Source:

254

ANDRE POISSON ETAL.

Fig. 17.— Interpretative cross sections through the central High-Atlas corresponding to the Lotharingian. This interpretation

favour a model of pure extension. The platforms are restricted to the southern margin and along the crests of the tilted

blocks. The elongated basins were the site of an active subsidence mainly at the end of this period. I, basinal facies

(ammonite bearing marls and limestones); 2, shallow marine carbonates; 3, coral reefs; 4. basement (mainly

Palaeozoic); 5, accumulation of molluscs; 6. tepee structures; 7, sponge reefs.

Fig. 17.— Sections transversales interpretatives du Haul-Atlas central correspondant an Lotharingien. Cette interpretation

reprend le modele d'extension pure. Des plates-formes residuelles persistent en bordure de la marge sitd et le long des

cretes des blocs bascules. Les bassins etroits ont ete subsidents au coins de cette periode ; 1. facies de bassin (/names

et calcaires a ammonites) : 2. carbonates matins littoraux : 3. recifs de coraux ; 4. substratum (PaleozoTque

essentiellement): 5 , accumulations de mollusques ; 6. structures en tepee ; 7. recifs a spongiaires.

CONCLUSION

As a conclusion the following points have to be emphasized:

— several general formations have been defined and correlations between facies and

palaeoenvironments are possible along this section, and these correlations may be extended at the scale

of the High-Atlas;

— an initial shallow marine platform suddenly covered all the High-Atlas during early Liassic time.

Open marine basin was to the east (eastern Neotethyan Mediterranean). Subsidence was active;

—- basins developed at the expense of this initial platform as early as Sinemurian by faulting (rifting

remained active);

— subsidence accompanied the initiation of the basins;

— large platform areas persisted along the northern and (mainly) southern margins of the High-Atlas

after the formation of the basins;

narrow platforms persisted for a time (at least up to late Liassic time), along the crests of tilted

blocks;

— two periods of active subsidence can be distinghished: during early-middle Liassic times the

basins resulted from syn-rift extensional tectonics; during Toarcian, Aalenian and early Bajocian times.

And restricted to some areas only during Bathonian times. Correlated to new extensional tectonic events

in the platforms and compressional events in the axial part of the belt which are marked by the beginine

of a new magmatic stage.

General mechanisms tor subsidence history have to be studied in more detail. In this area, eustatic

sea level fluctuations have minor influence on subsidence.

JURASSIC STRATIGRAPHIC CORRELATIONS IN CENTRAL HIGH-ATLAS (MOROCCO)

255

ACKNOWLEDGMENTS

This work was funded by Peri-Tethys Program, the Ministere de l'Energie et des Mines (Rabat) and

the Universite Paris-Sud (Equipe CNRS Geodynamique Interne et Geophysique). T. JACQUIN help us

for subsidence analysis. Two referees gave constructive criticism of the manuscript. We would like to

thank Rachel FLECKER for her revision of the English version, Genevieve ROCHE and Laurent DAUMAS

for the drawing of the pictures, and Gerard COQUELLE for the photographs.

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Choubert, G. & Faure-Muret, A., 1962.— Evolution du domaine atlasique marocain depuis les temps paleozoi'ques: Livre a

la memoire du Pr P. Fallot. Memoire hors serie, Societe geologique de France, Paris, 1: 447-527.

Debar, G.. 1962.— Notes sur la paleogeographie du Lias marocain: livre a la memoire du Pr P. Fallot. Memoire hors serie,

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Du DRESNAY, R.. 1964.— Les discontinuites de sedimentation pendant le Jurassique, dans la partie orientale du domaine

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Du Dresnay. R.. 1977.— Le milieu recital fossile du Jurassique inferieur (Lias) dans le domaine des chatnes atlasiques du

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Hadri. M., 1993.—- Un modele de plate-forme carbonatee au Lias-Dogger dans le Haut-Atlas Central au nord-ouest de

Goulmina, Maroc. These Doctoral, Universite Paris-Sud, Orsay. France: 1-272, 1 carte HT. 1/100 000.

Haq. B.U., Hardenbol, J. & Vail, P.R., 1988.— Mesozoic and Cenozoic chronostratigraphy and eustatic cycles. In: C.K.

Wilgus, B.S. Hastings, C.G. Kendal. H. Posamentier, C.A. Ross & J. Van Wagoner (eds). Sea-level changes: an

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Jenny, J., 1988.— Carte geologique du Maroc au 1/100 000. feuille Azilal (Haut-Atlas central). Memoire explicatif. Notes et

Memoires du Sendee geologique du Maroc, 339: 1 -104.

JOSSEN, J.A. & Filali-Moutei, J.. 1992.— A new look at the structural geology of the southern side of the Central and Eastern

High-Atlas mountains. Geologische Rundschau, 81, 1: 143-156.

Laville, E., 1981.— Role des decrochements dans le mecanisme de formation des bassins d'effondrement du Haut-Atlas

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312.

Laville, E. & Fedan, B., 1989.— Le systeme atlasique marocain au Jurassique: evolution structurale et cadre geodynamique.

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LeMarec, A. & Jenny, J„ 1980.— L'accident de Demnat, comportement synsedimentaire et tectonique d'un decrochement

transversal du Haut-Atlas central (Maroc). Bulletin de la Societe geologique de France. Paris, (7). 22 . 3: 421-427.

Milhi, A., 1992.— Stratigraphie. fazies und palaogeographie des Jura am Siidrand des zentralen Hohen Atlas (Marokko).

Berliner geowissenschaften, Abh.. Berlin, (A), 144 : 1-93.

Sadki, D., 1992.— Les variations de facies et les discontinuites de sedimentation dans le Lias-Dogger du Haut-Atlas central

(Maroc): chronologie, caracterisation, correlations. Bulletin de la Societe geologique de France, Paris. 163 . 2: 179-186.

Septfontaine, M., 1985. — Milieux de depots et foraminiferes (Lituolides) de la plate-forme carbonatee du Lias moyen du

Maroc. Revue de Micropaleontologie, Paris, 28. 4: 265-289.

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256

ANDRE POISSON ETAL.

Stanley, R.G., 1981.— Middle Jurassic shoaling of the Central High-Atlas sea near Rich. Morocco. Journal of Sedimeniarv

Petrology, 51. 3: 895-907. 7

Studer, M.A., 1987.— Tectonique et petrographie des roches sedimentaires. eruptives et metamorphiques de la region de

TounfRe-Tirrhist (Haut-Atlas central mesozoique. Maroc). Notes et Memoires du Sendee geologique du Maroc, 43.

STUDER, M. & Du Dresnay, R., 1980. Deformations synsddimentaires en compression pendant le Lias superieur et le Dogger

auTWIrhi, (Haut-Atlas Central de Midelt, Maroc). Bulletin de la Societe geologique de France, Paris, (7), 22,°3:

Warme, J.E., 1988.— Jurassic carbonate facies of the Central and Eastern High-Atlasrift, Morocco. In: V.H. Jacobshagen

( ed.). The Atlas system of Morocco. Lectures and Notes in Earth-Siences, 15: 169-199.

Source: MNHN, Paris

The Permian basins of Tiddas, Bou Achouch and

Khenifra (central Morocco). Biostratigraphic and

palaeophytogeographic implications

Jean BROUTIN'", Habiba AaSSOUMI" 1 , Mohammed El WARTITI '

Pierre FREYTET ma >, Hans Kerp '% Cecilio Quesada 151

& Nadege TOUTIN-MORIN 161

11 Laboraloire de Paleobotanique et Paleoecologie, Universite Pierre et Marie Curie

12, rue Cuvier. F-75005 Paris. France

121 Universite Mohammed V. Faculte des Sciences. Laboratoire de Geologie Appliquee. Avenue Ibn Batouta,

B.P. 1014. Rabat. Morocco

<5) 41 rue des Vaux mourants. F-91370, Verrieres le Buisson. France

141 Abt. Palaobotanik, Westfalische Wilhelms-Universital. Hindenburgplatz 57-59. 48143 Munster. Germany

151 Direccion de Geologia, 1TGE, Rios Rosas 23. 28003 Madrid. Spain

161 Universite d'Orleans, Departement des Sciences de la Terre. UMR 6530. FR09 du CNRS. BP 7659.

F-45067 Orleans Cedex 2. France

ABSTRACT

The intramontane deposits of the Tiddas, Bou Achouch, and Khenifra basins (Central Morocco), yielding outsanding

palaeofloras from late Early to “Middle" Permian age, have been extensively studied during the last years. Sedimentary facies,

lithostratigraphy. occurrence of bimodal magmatic events, macro- and microfloral contents, evidence that these deposits are

more or less coeval in the three basins. Our last pluridisciplinary field works, carried out in the central Morocco basins, show

they were deposited under tectonic, geographical (latitude, altitude) and climatic conditions quite similar with those observed in

the coeval basins of south-western Spain. The palaeoecological study of the fossil material from Tiddas led to suggest a warm

humid climate with somewhat irregularly distributed drought periods. Based on all available palaeontological data (macrofloras

preserved as impressions-compressions or permineralized structures; microfloras; vertebrate foot-prints), the age of these

Spanish and Moroccan continental deposits can be estimated as Kungurian (= Bolorian). The palaeophytogeographical

implications are analysed through comparisons with the Permian floras already described in the Niger and Gabon i.e. along a

Broutin, J., Aassoumi. H., El Wartiti, M., Freytet, P.. Kerp. H., Quesada. C. & Toutin-Morin, N„ 1998. — The

Permian basins of Tiddas, Bou Achouch and Khenifra (central Morocco). Biostratigraphic and palaeophytogeographic

implications. In: S. Crasquin-Soleau & E. Barrier (eds), Peri-Tethys Memoir 4: epicratonic basins of Peri-Tethyan

platforms, Mem. Mus. natn. Hist, nat., 179 : 257-278. Paris ISBN : 2-85653-518-4.

Source MNHN, Paris

258

JEAN BROUT1N ETAL.

North-Soulh transect from Spain to Central Africa. The occurrence of floristical exchanges have been evidenced during the

Permian time between the southern margin of the Laurasian domain and the northern part of the Gondwanan floral realm. The

main biostratigraphical and palaeogeographical implications of these studies are analysed.

RESUME

Les bassins permiens de Tiddas, Bou Achoud ef Khenifra (Maroc central). Implications biostratigraphiques et

paleophytogeographiques.

Les depots intramontagneux des bassins de Tiddas. Bou Achouch et Khenifra (Maroc central), qui ont livre des paleoflores

d'age Permien inferieur-Permien moyen. ont ete etudiees intensivement au cours des dernieres annees. Les facies sedimentaires,

la Iithostratigraphie, Fexistence d'un magmatisme bimodal et le contenu macro- et microfloristique indiquent que ces depots

sont plus ou moins contemporains dans les trois bassins. Nos derniers travaux pluridisciplinaires sur le terrain ont permis de

montrer que ces trois bassins se sont deposes dans un contexte tectonique similaire. une situation geographique homologue

(latitude, altitude) et sous des conditions climatiques identiques aux gisements fossiliferes contemporains du Sud Ouest de

l'Espagne. Sur la base de I'ensemble des donnees paleontologiques (macroflores conservees en empreintes, compressions ou

structures permineralisees ; microflores ; empreintes de pattes de vertebres) un age Kungurien (= Bolorien) peut etre propose

pour les bassins marocains et espagnols. L'etude paleoecologique du materiel fossile de Tiddas suggere un paleoclimat chaud et

humide. affecte par des "stations" seches de periodicite irreguliere. Les implications paleophytogeographiques de ces resultats

sont analysees par des comparaisons avec les paleoflores permiennes decrites au Niger et au Gabon, c’est-a-dire le long d’un

transect Nord-Sud de l'Espagne a FAfrique Occidentale. L’existence d'echanges floristiques au cours du Permien entre le Sud

du domaine laurasien et le Nord du Gondwana a ete mise en evidence. Les principales implications biostratigraphiques et

paleogeographiques de ces etudes sont analysees.

INTRODUCTION

In Morocco, the Permian was a transitional period between the Hercynian orogeny and the Mesozoic

distension phase. The former is characterized by strong compression (during the Westphalian); the latter

is related to the opening of the Atlantic Ocean in the West and palaeogeographical changes in the

eastern Tethys. During this transitional period, until the end of the Palaeozoic, intense fracturing, cutting

the Atlas-Mesetian basement into mobile blocks, took place, with subsequent episodic reactivations

during the entire Mesozoic and Cenozoic. A compressive phase in the Early Triassic resulted in folding

and tilting of the Permian deposits (EL WARTITI & FADLI. 1985). The Permian basins formed on a serie

of mainly transverse structures, related to the regional compressive tectonic phase with NNE-SSW

strike. These graben structures are considered to be formed during the Asturian phase and deformation

eventually took place during the Saalian phase (MlCHARD et al., 1978), while a tectonic reactivation

resulted in volcanism and the ascent of granitic plutons (CAILLEUX et al., 1986).

The individual, isolated, usually small Permian basins are located around the margin of the central

Morocco Hercynian massif (Fig. I). They are the remnants of intramontane basins characterized by a

strong subsidence and filled with detritic, predominantly red-coloured sediments. Carbonates and fine¬

grained, grey-coloured, lacustrine and palustrine sediments occur locally and are sometimes rich in plant

remains. They are part of tining-upward sequences typical for terrestrial environments and consist of

conglomerates, sandstones and mudstones. The sequences, showing very strong variations in thickness

within a single basin, reflect the depositional history and the decrease of the hinterland relief during the

Permian. Extensional tectonics played a fundamental role in the subsidence, through the activity of

normal, synsedimentary faults, the elevation of horsts, and particularly the continuous activity of the

basin boundary faults leading to a rejuvenation of the hinterland relief which provided detritic material.

Large and deep faults, being the continuation of tectonic structures in the basement, favoured the

formation of the granitic plutons between the late Visean and the Late Permian (BOUSHABA et al.,

1987), and the ascent of a bimodal volcanism, dominated by calc-alkalic magmas, prior (Tiddas), during

(Bou Achouch. Chougrane. Mechraa Ben Abbou), or after the filling of the basins (Khenifra).

The palaeoecological study of the fossil material from the Tiddas basin (impressions-compressions,

permineralized woods, vertebrate foot prints, roots-related pedological nodules) led to suggest a warm

humid climate with somewhat irregularly distributed drier periods. Their biostratigraphic attribution to

the Early-Late Permian is based on the classification of more than sixty taxa of macro- and microfloral

plant remains (Table I and Figs 8-11).

Source: MNHN, Paris

THE PERMIAN BASINS OF TIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

259

Fig. 1.— Permian basins of Morocco. Modified after Michard et al., 1978 and El Wartiti, 1990.

Fig. I .— Bassins permiens du Maroc. D'aprisMlCHARD et a!., 1978 el ElWartiti, 1990.

The last field investigations by the authors (1994), undertaken within the framework of the Peri-

Tethys Program, evidenced the strong similarities between the Moroccan “Khenifra”, “Bou Achouch"

and "Tiddas” basins themselves, and with the corresponding soutwestern Spanish "Rio Viar” and

“Guadalacanal-Urbana- San Nicolas del Puerto" ones. Sedimentary facies, occurrence of bimodal

magmatic coeval events, macro- and microfloral contents, suggest that all these basins were built up

under very similar tectonic conditions. Geographical (latitude, altitude) and climatical context were also

quite similar.

It is clear that the Moroccan basins, on the one hand, and the Spanish ones, on the other hand,

represent only residual parts of originally much more widespread intramontane basins (may be even of a

single one). But the distance between Moroccan and Spanish areas and, above all, the different

basements on which the Moroccan and Spanish Permian strata lie suggests that they did not pertain to a

same basin.

Three Permian basins, Tiddas-Souk-es-Sebt des Ait Ikkou (or simply "Tiddas”), Bou Achouch and

Khenifra, will be described here in more detail, because they show numerous similarities in facies,

tectonic setting, and they all contain an abundance of well-preserved plant remains which indicate the

same age for all these three basins.

260

JEAN BROUTIN ETAL.

STRATIGRAPHICAL SECTIONS

Tiddas

The Tiddas basin is located in the northern part of the Hercynian Massif. This elongated basin is 17

km long and up to 2 km wide, and is oriented in NE-SW direction (Fig. 2). In the southwest, the Permian

unconformably overlies upper Visean flysch deposits. In the northwest, the Permian is unconformably

overlain by Upper Triassic sediments which contain a Carnian flora (Figs 3-4), or by Quaternary

sediments.

The Permian succession starts with reddish conglomerates containing boulders and pebbles of

basement rocks (predominantly sandstones, quartzites, schists, and rarely crinoidal limestones). These

conglomerates are to be interpreted as alluvial fan deposits. These are followed by respectively

Fig. 2.—Simplified geologic map of the Tiddas-Souk-es-Sebt basin, after El Wartitl 1981, completed.

F,a 2 -~ Car,e gtologique simplifiee du bassin de Tiddas-Souk-es-Sebt, d’apres ElWartiti. 1981, completee.

Source: MNHN, Paris

THE PERMIAN BASINS OF TIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

261

Red mudstones

Fine sandstones

and cinerites

Conglomerates

% Vegetal remains

(^Vertebrate foot prints

Fig. 3.— Location of the studied sections (1-4) of the Tiddas basin. Modified after ElWartiti, 1981. Fig. 50; 1990, Fig.49,

modified.

Fig. 3 .— Localisation des coupes eludiees ( 1-4) dans le bassin de Tiddas. D apres ElWartiti, 1981, Fig. 50 : 1990, Fig. 49.

modifiee.

Source: MNHN, Paris

262

JEAN BROUT1N ETAL.

conglomerates with a basal scouring surface, fluvial sandstones and red mudstones, occurring in thin, up

to one meter thick but sometimes incomplete lining-upward sequences. The fine-grained sandstones are

often rich in invertebrate tracks and burrows. The red mudstones, which are locally indurated and

calcified, show ripple marks, desiccation cracks and imprints of rain drops. These thus represent a Hood

plain facies; in (he centre of the basin they are associated with lacustrine and palustrine limestones in the

upper part of the sequences. Lens-shaped pedogenic, 0.5-1.0 m thick horizons are locally developed in

the red mudstones. These represent hydromorphic soils with carbonate nodules in a more or less circular

arrangement (Fig. 2) which are interpreted as encrustations around the stilt roots of certain Corded tes

(AASSOUMI etai, 1993).

In the upper part of the sequence, vertebrate footprints were discovered (BROUTIN et al., 1987). They

mainly belong to Hyloidichnus , a taxon that is known from the Lower Permian of Arizona (U.S.A.),

Lodeve (France) and Thuringia (Germany). Two other forms can be compared respectively with the

500 m.

400 m.

300m.

Triassic

200m.

100 m.

Visean

Fig. 4.— Synthetic succession of the Tiddas basin. Coupe synthetique

clu bassin de Tiddas. 1 : conglomerates and sandstones,

conglomerats el gres ; 2: volcanic tuffs, tuffs volcaniques ; 3:

red beds (mudstones with palaeosols, rare vegetal remains and

foot-prints), niveaux rouges (argilites a paleosols, rares

debris vegetaux el empreintes de panes) ; 4: grey beds (fine

sandstones, cinerites and mudstones with vegetal remains,

niveaux gris (gres fins, cinerites et argilites a restes

vegetaux) ; F: main fossiliferous levels, principaux lits

fossiliferes.

Source: MNHN, Paris

THE PERMIAN BASINS OF TIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

263

Permian ichnotaxon Amphisauroides discessus Haubold, 1970 and the genus Gilmoreichnus. The latter

form is most similar to the “species” G. brachydactylus?, from the Lower Permian of Thuringia

(Germany), and Antichnium salamandraides (Geinitz) Haubold (Det. G. Gand). A few thin, 20-60 cm

thick grey mudstone layers locally occur within the red mudstones; they contain thin coal seams and are

rich in well preserved plant remains.

The lower third of the section, or lower member, shows a predominance of coarse-grained sediments;

sediments of the overlying upper member are finer and more fossiliferous, and the pebbles are more

rounded. Both members show a fining upwards and they represent a positive megasequence; they are

estimated 500 m in thickness.

Two main volcanic events, expressed by rhyolitic and andesitic volcanism, affected the Tiddas area

(CAIL.LEUX et al., 1982). Rhyolitic rocks are exposed in the northwestern part of the basin. Lavas are

grey-coloured near the emission point, and then subsequently become yellowish red at some distance.

Some ignimbritic rhyolites and bedded pyromerides occur locally. A system of intrusive veins in the

upper Visean is probably the source of the lavas. Rhyolite pebbles are abundant in Permian deposits of

the Souk-es-Sebt area, and fine, chocolate-brown tuffs, are sometimes intercalated in the conglomerates.

Andesitic rocks are found in the southwestern part of the basin, forming small domes in the upper

Visean. These andesites are massive and dark-grey in colour near their emission point; they locally

become dark purple, with white patches or having a brecciated appearance, indicating a considerable

release of gasses from the magma fluid. Andesite pebbles and tuffs are present in the conglomerates of

this part of the basin. Finally, basic intrusive veins cut through the Permian series in the southwestern

part of the basin (Fig. 4).

This calc-alkaline volcanism is related to the compression phase at the end of the Carboniferous and

the beginning of the Permian. This volcanism was erupted along a local N 65 E trending, extensionnal

fault zone (EL Wartiti, 1990).

The sediment sources do not show a predominant transport direction. The material is of local origin,

from the Visean basement, granitic plutons, and Permian volcanic rocks in the northeast and southwest.

BOU ACHOUCH

The Bou Achouch basin is located on the northern side of the Hercynian Massif, approximately

20 km East of Tiddas (Fig. 1). It is a small basin, just 1 km 2 , and the outcropping rocks are intersected,

displaced and bounded by faults which also affect the basement. The layers generally dip E to ENE

(Fig. 5). The Permian unconformably overlies the upper Visean, which consists of grey, folded flysch

deposits; in the north and northeast the Permian is covered by Pliocene deposits.

The reddish conglomerates with poorly rounded pebbles of Visean sandstones, quartzites and schists,

in the basal part of the sequence are interpreted as alluvial fan deposits (Fig. 5). They are overlain by

fluviatile sandstones and red flood plain mudstones, sometimes with lenticular, thin, up to 20 cm thick

limestone intercalations, and yellowish-ochrous carbonate nodules in the mudstones, indicating

respectively lacustrine and palustrine environments (hydromorphic palaeosols). In the upper part of the

sequence, a volcanic acidic phase is represented by a grey rhyolitic intercalation (section 3) and two

types of ash tuffs (sections 1, 2, 3). One type is fine-grained, grey-blue, compact and well bedded,

showing a fining upwards indicating a slow settling. The other type is yellow, rich in coarse detritic

elements and numerous plant remains. Within the basin these ash tuffs with plant remains from the

adjacent hinterland form marker horizons. This fining upward succession forms the lower member of the

Permian at Bou Achouch.

In the upper part of the sequence, yellowish conglomerates contain pebbles of rhyolite and basement

rocks, which are smaller and better rounded than in the lower member. The first layers of these stream

deposits show a basal scouring surface, that indicates a new period of erosion. Approximately 30 cm

thick, blue green ash tuff layers which show a fining upwards and pass into coal layers where abundant

plant remains are common. Restricted environmental conditions are indicated by abundant dolomite in

the top of this upper member, that as a whole can be also considered as a fining upwards sequence. A

second volcanic episode, also calc-alkaline (SAUVAGE et al., 1983) resulted in the formation of intrusive

264

JEAN BROUTIN ETAL.

Fig. 5-

EXPLANATIONS

MAP

Post-Hercynian

Formations

^ v v V/ v

v v v u v v

•J \l V •J V V

Permian

volcanic rocks

vv-iSPermian

:.. i sedimentary

rocks

Visean

basement

1,2,3

: Sections

Fault

10m

Section 1

ENE

SECTIONS

V s/ V v V

v M \J V V V

V V v V V v

Volcanic rocks

Coal layers

| Cine rites

Sandstones and

^g^^-j-vj conglomerates

Visean

basement

Geologic map of the Bou Achouch basin and location of the studied sections. Modified after Cailleux et al 1982

and El Wartiti, 1990.

-. Carle geologique clu bassin de Bou Achouch el coupes etudiees. D'apres Cailleux et al., 1982 el El Wartiti 1990

modifiee.

Source: MNHN, Paris

THE PERMIAN BASINS OFTIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

265

Ante Permian

Permian

a rofllllUrous

grey levels

b conglomerates

c mudstones

Post Permian

Permian

Volcanic rock

inrust

Syncime

Reversed anticline

FlG. 6.— Simplified geologic map of the Khenifra Basin. After El Wartiti 1990, completed.

Fig. 6 .— Carle geologique simplijUe dit bassin de Khenifra. D'apres Ei.Wartiti. 1990. completee.

Source;

266

JEAN BROUTIN ET AL.

veins and plugs of purple-grey rhyodacites and dark-grey to dark-green andesites, found in the eastern

and northern parts of the basin.

The whole series is not more than 60 m thick; the sediment source seems to have been located

primarily in the east and south-southeast.

KHENIFRA

The Khenifra basin (Fig. 1) is the easternmost

basin is also the largest one regarding its present

V VVV S' )

Rhyolite

1500 m-

Conglomerates

and sandstones

with rare

mudstones

Scour surface

, - (Fault)

1000 m-

Projection of

fossiliferous

grey levels

Mudstones with

sandstones and

rares conglomerates

500m

Conglomerates

and sandstones

with rare

mudstones

Debris flow

. Unconformity -

Substrate (Ordovician-

Visean)

Q-

Fig. 7.— Synthetic succession of the Khenifra Basin. ("A -

B", Fig. 6). After E L Wartiti, 1990, Fig. 87.

completed.

FlG. 7.— Coupe synthetique du bassin de Khenifra ("A - B ”,

Fig. 6). D'apres El Wartiti 1990, Fig. 87. completee.

one of the Permian basins of central Morocco. This

outcrop area (about 100 km 2 ). The basin is cut into

three parts by transverse faults which run in

SSW-NNE direction, the southern part of the

basin forms a wide regular synclinal structure

(Fig. 6).

The Permian series unconformably overlies

Ordovician schists, quartzites and psammites (N,

NE and S), Devonian sandstones, siltstones and

limestones (N and NW), Visean sandstones,

claystones and limestones (W). This folded

basement now forms a relief surrounding the

Permian basin. Compression took place after the

Permian but before the Late Triassic; the normal

faults limiting the basin reacted as inverse

overthrusts. The Upper Triassic unconformably

overlies the Permian (Fig. 6).

The Permian series consists of three members

(Fig. 7).

Sedimentation of the lower member starts

with conglomerates containing coarse pebbles of

Ordovician and Visean sandstones and quartzites,

and Visean and Devonian reefal limestones. The

lower member consists of a succession of fining

upward sequences (conglomerates - sandstones -

mudstones), revealing the subsidence of the

basin. These materials correspond to alluvial fans

deposits, with sometimes debris flow deposits.

Toward the basin centre, they become

channelised. In the upper part of this member,

and in the S of the basin, ripple marks and thin

laminations appear in fine grained sandstones and

indurated grey mudstones, platy splitted by

weathering.

The middle member mainly consists of red

mudstones, interbedded with occasional layers of

beige sandstones and grey, indurated mudstones,

platy splitted by weathering. Plant remains,

locally associated with azurite and malachite

mineralizations, are frequent in the light-coloured

horizons. A few thin lignite horizons, a few cm in

thickness, have been reported from the area near

Khenifra (TERMIER, 1936). In the area of

Bouzouggargh, a lateral transition from red Hood

plain mudstones to grey lacustrine mudstones can

be found; both mudstones are rich in plant

remains. Large linguoid ripples (Nkhilat area),

Source: MNHN. Paris

THE PERMIAN BASINS OFTIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

267

desiccation cracks, invertebrate burrows and plant remains occur in the grey fine-grained sandstones.

This middle member forms, with the lower member, a fining-upwards megasequence.

The upper member consists of coarser material, but the pebbles are well sorted, and. mostly smaller

than those in the lower member. This indicates a new phase of erosion, related to a local tectonic phase,

and a predominantly fluviatile transport. The fine-grained sandstones sometimes show laminations,

ripple-marks and rain imprints. Pedological phenomena, such as marmorisation patches and carbonate

nodules locally occur in the red mudstones; the carbonate nodules were formed by the encrustation of

plant remains during rain periods. This upper member represents the beginning of an incomplete fining

upwards megasequence.

In the northwestern part of the basin (Fig. 6) a thick volcanic unit is exposed, consisting of two types

of magmatites (YOUBI, 1990):

— the first, acid and viscous magmatite type, comprises red, yellow or grey rhyolites - reaching a

thickness of 150 m and intersecting the Permian in the middle part of the basin ignimbritic rhyolites and

purple grey and straw-yellow rhyodacites. The magmas ascended via large faults coming from the

basement;

— the second type of magmatite basic, is an explosive magmatite type, which intruded in the former

and consists of andesitic domes and black or green dacites.

Several, approximately 10 m thick layers of chocolate-brown ash tuffs and small occurrences of

pyroclastites are locally present in the volcanic massif.

This volcanism, which is calc-alkaline (YOUBI & CABANIS, 1995) like in the Tiddas and Bou

Achouch basins, is only slightly younger than the basin filling, because pebbles consisting of these

volcanic rocks are absent in the coarse sediments, although a radiometric dating indicated a Permian age

(264 ± 10 Ma. Jebrak, 1982).

DEPOSITIONAL ENVIRONMENTS

Field observations and detailed laboratory studies (El WARTITI, 1990) allowed the reconstruction ot

the basin history and the sedimentary successions appear to be similar in most ot the Moroccan Permian

basins, especially in central Morocco, which are all filled with terrestrial, predominantly detntic

material.

At the base coarse-grained sediments being the result ot the erosion of the adjacent reliefs, aie

abundant, mainly near the basin margins, where they occur in the form ot alluvial fan deposits, oi

sometimes as mudflows. This lithology reflects a very local origin.

Then the sandstones of fluviatile facies become predominant. With each flooding, meandering

channels filled with conglomerates cut into the underlying deposits in the central part of the basin

Braided channels are common in the Tiddas and Khemfra basins, as well as in the Chougrane ani

Mechraa Ben Abbou basins that are not described in this paper.

The top of the basin fill (Tiddas), or the top of the megasequences which can consist of several

phases (upper part of the middle member in the Khenifra basin), comprises fine sediments, mainly red

flood plain mudstones, which were deposited during tectonically calm periods when the surrounding

relief was low. During rainy periods small lakes and ponds were formed in these wide, s.hy P ains in

which thin lens-shaped carbonate layers were deposited (Tiddas Bou Achouch, KheniIra, Chougrane).

Sometimes (Mechraa Ben Abbou), stromatolitic encrustations, charophyte remains and ostracod shells

indicate the presence of more permanent, somewhat deeper waters (Damotte et al, 1993 ). l e

periodical desiccation of the lake edges only resulted in the formation ot carbonaite nodules TU

encrustation of roots can occur during flooding periods (Tiddas). In some cases, s'ow set tl ' n | ot

particles (volcanic ashes in the Bou Achouch Basin, grey platy splitted silts, andI clays inthe Khenifra

Basin) in these lakes is associated with the deposition ot plant material which onginated from

immediate vicinity or from the adjacent hinterland.

MNHI\

268

JEAN BROUTIN ET AL.

PALAEOBOTANIC BIOSTRATIGRAPHICAL DATA

The Bou Achouch, Tiddas and Khenifra basins have yielded rich and diversified macrofloras.

Conversely, our attempt for microfloras extractions have been successful in only one grey pelitic

horizon of the Khenifra basin (“Nkilat” locality, on the Oued Oum Rbia right bank: Fig. 6).

Macroflora

The “conifer dominated" Bou Achouch. Tiddas and Khenifra floral assemblages are similar enough

(as clearly shown in table 1) to suggest that these three basins are more or less coeval.

Looking for the most biostratigraphically relevant forms, we can point out the occurrence of:

— a rich conifer complex characteristic of euramerian Lower Permian “sensu lato”, including forms

such as : Otovicia hypnoides Kerp et al. (Fig. 8; a,b); Culmitzschia (al. Walchia) laxifolia Clement-

Westerhof (Fig. 8; c); Culmitzschia (al. Walchia) parvifolia Clement-Westerhof (Fig. 8; d, e, g);

Culmitzschia (al. Walchia) speciosa Clement-Westerhof (Fig. 8; f) and Feysia minutifolia Broutin &

Kerp (Fig. 8; h);

— a diversified Calliperids assemblage of sterile foliage and reproductive organs: Rhachiphyllum

schenkii Haubold & Kerp (Fig. 9; a. e), Lodevia nicklesii Haubold & Kerp (Fig. 9; c), Dichophyllum cf.

flabellifera Haubold & Kerp (Fig. 9; h). Autuniopsis sp.= ovuliferous organs (Fig. 9; b, d), all forms

common in the euramerian Lower Permian; Peltaspermum martinsii Poort & Kerp vegetative shoots

(Fig. 9; f, g) has been found in assocation with numerous very well preserved peltaspermaceous

ovuliferous organs (work in progress) : these taxa became common only during the Late Permian;

— a highly diversified Gingophytes association, the occurrence of which, elsewhere in the world, is

in latest Early Permian (Fig. 10; a-h).

Microflora

The only one discovered microfloral association is dominated by monosaccates pollen grains

pertaining mainly to the genus Potonieisporites (Fig. 11; a, b, d, f, g). But bisaccates grains are also

represented by non striate forms such as Gardenasporites sp. (Fig. 11; k) and striate elements such as

Complexisporites polymorphus (Fig. 11; o), Lunatisporites sp. (Fig. 11; i), Striatoabieites sp. (Fig. 11;

P)-

This microflora is closely similar to the assemblages well known in the “Muse Formation” of the

french Autun basin (“lower Autunian”: CHATEAUNEUF^t al., 1992).

In addition with this palynological association, the macroflora collected, at that time, in the Khenifra

basin lacks the Gingkophytes complex. So, we can suppose that the fossiliferous strata of this basin

could be slightly older than those of the Bou Achouch and Tiddas basins (see Table 1). We still have to

check this more accurately by new collecting in the Khenifra basin.

Fig. 8.— a: Otovicia hypnoides Kerp et at. Bou Achouch basin. Bassin de Bou Achouch ; b: I, Otovicia hypnoides Kerp et at;

2-detached conifere seed, Bou Achouch basin; graine isolee de conifere, Bassin de Bou Achouch. c: Culmitzschia (al.

walchia) laxifolia Clement-Westerhof. Tiddas basin, sample n° TBR.A20r; Bassin de Tiddas, ech. n° TBR.A20r. d. e:

Culmitzschia (al. Walchia) parvifolia Clement-Westerhof. Bou Achouch basin, sample n° B 1,16a et B 1.16b; Bassin de

Bou Achouch, ech. n° B 1.16a et BE 16b. f: Culmitzschia (al. Walchia) speciosa Clement-Westerhof. Khenifra basin,

sample n K.ms8; Bassin de Khenifra, ech.n° K.ms8. g: Culmitzschia (al. Walchia) parvifolia Clement-Westerhof.

Khenifra basin, sample n° K.msl3; Bassin de Khenifra, ech.n° K.msl3. h: Feysia minutifolia-like ultimate leafy shoot.

Khenifra basin, sample n° K.msl; rameaux ultimes de type Feysia minutifolia Broutin <6 Kerp. Bassin de Khenifra,

ech.n K.msl . Same scale, mime echelle : d, f-h.

Source:

THE PERMIAN BASINS OF TIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

269

Source. MNHN. Paris

270

JEAN BROUTIN ETAL.

Fig. 9.— a: Rhachiphyllum schenkii Haubold & Kerp. Pinna fragment showing intercalary pinnules. Bou Achouch basin,

sample n° BA88b9; Fragmen: d'une penne avec pinnules intercalaires. Bassin de Bou Achouch, ech. n° BA88b9.

Rhachiphyllum schenkii Haubold & Kerp. b. d: Autuniopsis sp.: bilateral ovuliferous discs, see the impression of 2

detached ovules (arrows). Bou Achouch basin, sample n° BA90b9; Autuniopsis sp. : disques oviliferes a symetrie

bilaterale ; remarquer les empreintes de 2 ovules detachees (fleches). Bassin de Bou Achouch, ech. n° BA90b9. c

Lodevia nicklesii Haubold & Kerp; Khenifra basin, sample n° Kms6; Bassin de Klienifra. ecli. n° Kms6 : e:

Rhachiphyllum schenkii Haubold & Kerp.Bou Achouch basin; Bassin de Bou Achouch. f, g: Peltaspermum martinsii-

like sterile foliage fragments. Bou Achouch basin, sample n° BA87b24 & BA87sl ; Fragments de pennes ultimes de

morphologie similaire a cede dufeuillage sterile de Peltaspermum martinsii. Bassin de Bou Achouch, ech. n°BA87b24

& BA87sl. h: Dichophyllum sp, cf.D. flabellifera Haubold & Kerp. Bou Achouch basin, sample n° BA87s6\

Dichophyllum sp, cf. D. flabellifera Haubold & Kerp. Bassin de Bou Achouch, ech. n° BA87s6.

Source: MNHN. Paris

THE PERMIAN BASINS OF TIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

Table 1.— Paleoflora and paleofauna of the Bou Achouch, Tiddas, Khenifra basins. Bold: figured species.

Tableau Paleoflore el Paleofaune des bassins de Bou Achouch. Tiddas. Khenifra. En gras : especes figurees.

BOU ACHOUCH TIDDAS KHENIFRA

« SAXONIAN » |

« SAX. »

AUTUN1AN 1

AUT.

Asterophyllites ci.dumasii

Annularia cf. hunanensis

Catamites cistii

Catamites cf. cistii

Catamites gigas

Catamites suckowii

Callipteridium marginatum

Catamites suckowii

Sphenopteris pseudogermanica

Sphenopteris germanica

Pecopteris cf. aspidioides

Neuropteris sp.

Odontopteris gimmi

Pecopteris cf. chihliensis

Lodevia nicklesii

Autuniopsis sp.

Pecopteris cf. densifolia

Ginkgophyllum sp.

Dichophyllum flahetlifera

Pecopteris cf. latenervosa

Cordaites cf. angulosostriatus

Peltaspermum sp.

Protoblechnum cf. wongii

Cordaites principalis

Rhachiphyllum schenkii

Odontopteris gimmi

Poacordaites sp.

Rhachiphyllum spp.

Taeniopteris abnormis

Culmitzschia laxifolia

Ginkgophyllum sp.

Taeniopteris sp. 1

Culmitzschia parvifolia

Ginkgoites spp.

Taeniopteris sp. 2

Culmitzschia speciosa

Sphenobaiera digitata

Rhachiphyllum schenkii

Ernestiodendron filiciforme

Sphenobaiera sp.

Ginkgophyllum sp.

Otovicia hypnoides

Cordaites cf. angulosostriatus

Walchia piniformis

Cordaites cf. principalis

Feysia minutifolia

Poacordaites sp.

.1.

Culmitzschia laxifolia

MICROFLORA

Culmitzschia parvifolia

Endosporites globiformis

Darnevella gracilis

Densoisporites sp.

Ernestiodendron filiciforme

Potonieisporites novicus

Ortiseia sp

Walchianthus sp.

N uskoisporites sp.

Feysia minutifolia

Potonieispor. bhadwajii

Feysia puntii

Potonieispor. doubingeri

Otovicia hypnoides

Playfordiaspora crenulata

Wale Ilia piniformis

Walchia piniformis

Florinites walikalensis

Walchianthus sp

Cordaicarpus sp.

Divarisaccus latesulcatus

aff. Pseudovottzia spp.

Gomphostrobus bifidus

Lantzipollenites sp.

Gomphostrobus bifidus.

Samar ops is sp.

Cortdaitina sp.

aff. Glossopteris anatolica

aff. Phylladoderma sp.

Parasaccites sp.

aff. Glossopteris communis

.n:.....,

.I .

Mosulipollenites sp.

aff. Glossopteris communis

VERTEBRAT

E FOOT PRINTS

Densipollenites sp.

aff. Venustostrobus

Hyloidichnus sp.

Gardenasporites sp.

aff.Plagiozamites sp.

Gilmoreichnus braehydactylus

Complexisporites sp.

Dicranophyllum spp.

Antichnium salamandroides

Striatoabieites sp.

Mostotchkia sp.

Figured species

272

JEAN BROUTIN ET AL.

PERMIAN PHYTOGEOGRAPHIC SEQUENCE ALONG THE NORTH SOUTH TRANSECT:

SOUTH-WESTERN SPAIN - GABON (Fig. 9)

The southwestern Spain “Guadalcanal-Rio Viar” Late Early Permian mixed flora

Locally coal-bearing continental strata, yielding fossil plant remains, occur in a few, generally small,

outcrops scattered within the Ossa-Morena / South-Portuguese structural zones boundary (BROUTIN,

1983). This boundary was reinterpreted recently (Quesada. 1991) as a cryptic Variscan suture. The

study of the rich macro- and microfloras led to give a "post Autunian - ante Thuringian” age to these

strata (BROUTIN, 1986). Among a Euramerian floral assemblage, including Walchia spp., Callipterids

Ginkgophytes associated with some hygrophilous “Stephanian” remnants, a lot of “exotic” elements

have been identified.

Cathaysian forms - Lobatannularia aff. L. sinensis ; Protoblechnum wongii Halle. Protoblechnum

sp„ Sphenopteris pseudogermanica Halle, Fascipteris cf. robusta Gu & Zhi ; associated with Raistrickia

and Knoxisporites Cathaysian-like microspores.

The Gondwanan forms appear to be more represented in the microfloral assemblages:

Plicatipollenites spp., including P. gondwanensis, Sheuringipollenites spp., Divarisaccus latesulcatus,

Schweizerisporites sp. (= spore monolete n°l, Permian of Gabon, in JARDINE, 1974), Cannanoropolis

spp, Crusisaccites spp. (BROUTIN & DOUBINGER, 1985). Some Macrofloral remains show more

disputable Gondwanan affinities (Li. 1986): Rhipidopsis spp., Phyllotheca spp., Ginkgophytopsis

kidstonii (BROUTIN, 1982).

The Central Morocco, Late Early Permian mixed flora

Based on the classification of more than sixty taxa, (Table 1 and Figs 8-11) the palaeoflora recovered

from the continental Bou Achouch. Tiddas and Khenifra basins appears to be coeval with the one of

south-western Spain and display the same phytogeographic characteristics (El Wartiti et al., 1990;

Aassoumi, 1994). Again, Cathaysian elements have been found: Pecopteris chihliensis Stockmans &

Mathieu, P. latinervosa Halle, Protoblechnum wongii Halle, Annularia hunanensis Gu & Zhi,

Sphenopteris pseudogermanica Halle.

Interestingly, the Gondwanan plants belong to the Glossopterids, as in the Haushi-Huqf area. There:

sterile foliage similar to Glossopteris communis Feistmantel, Glossopteris anatolica Archangelsky &

Wagner and scale-leaves related with Lidgettonia, Eretmonia, Venustostrobus fertile organs have been

recognized (BROUTIN et al., in prep.).

The palaeoecological study of the recovered fossil material (impressions-compressions, silicified

woods, vertebrate foot-prints, roots-related pedological nodules, etc.) led to suggest a warm humid

climate with somewhat irregularly distributed drought periods.

Our last pluridisciplinary field works, carried out in the central Morocco basins (1994) showed that

sedimentary facies, macro- and microfloral contents and occurrence of bimodal magmatic coeval events

are the same as in the southwestern Spanish basins. Therefore, these Moroccan and* - Spanish basins were

deposited under quite close tectonic, geographical (latitude, altitude) and climatic conditions (=

Cathaysian-like' warm-humid conditions). Based on all the now available palaeontological data, the

age of these Spanish and Moroccan continental deposits can be estimated as Kungurian (= Bolorian)

Fig. 10.

Bou Achouch basin, sample n° BA87b20 el 20'. Bassin cle Bou Aclwucli . ech

echelle : c-g.

Source:

THE PERMIAN BASINS OFTIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

273

Source: MNHN. Paris

274

JEAN BROUTIN ETAL.

Source: MNHN. Pahs

THE PERMIAN BASINS OFTIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

275

Fig. 12.— Synthetic succession of the Tarat Formation. Arlit

area: Niger (modified after BROUTIN el al., 1990).

FIG. 12.— Colonne synthetique de la Formation du Tarat.

region d'Arlit : Niger (modife d'apres BROUTIN et al.,

1990).

However, if it emerges that they represent only

remnants of much larger intramontane basins, the

different nature of the substrata on which

Permian Moroccan and Spanish rocks were

deposited could suggest that these deposits did

not belong to the same single basin.

Western and Central Africa

The available palaeobotanical and palyno-

logical data show that the southernmost limit

of Euramerian elements extension, during the

Permian, lies in central Africa (Gabon) through

western Africa (Niger).

In the upper sequence of the continental Tarat

formation (Arlit region, northern Niger) a mixed

microflora amalgamates Gondwanan elements

and typical Euramerian taxa (Fig. 12).

Based on a comparison with Gondwanan and

Euramerian palynological zonation (in the

absence of any marine data), the age of this

microflora was estimated to be comprised

between the Kungurien and the Ufimian or, may

be, the early Kazanian (BROUTIN et al., 1990).

Extracted from the same levels, the

macrofloral assemblage is dominated by

Euramerian plants including, especially : Autunia

(Callipteris) conferta, Lodevia (Callipteris)

nicklesii, Walchia pinifonnis , Walchia spp. and

Cordaites spp., assemblage considered as typical

of the Lowest Permian (Autunian) in Western

Europe. After DE ROUVRE (1985) the associated

fructifications have Gondwanan affinities.

In the Tarat succession, all the known ante-Permian (Visean - Namurian) microfloras are typically

Gondwanan. similar with those described in Argentina, Zaire, Australia (DOUBINGER in El Hame

1983).

The microfloral Permian sequence in the Agoula succession (Gabon) has been well characterized by

Jardine (1974). In the basal part, the Sakmarian "P II" assemblage is undisputably a Gondwanan one, it

is overlain by a "P III" association very similar in composition with the Nigerian upper Tarat microtlora

and likely more or less coeval. At the top of the succession, Jardine (1974) noticed the occurrence oi

Klausipollenites schaubergeri, Lueckisporites virkkiae , Jugasporites sp. and Limitisporites sp.

representatives of “a typical north-European Late Permian assemblage .

Fig 11 - Palynological association from the Khenifra basin CNkhilat" locality). Association palynologique du bassm de

Khenifra (local ite " Nkhilat"). a: Poionieisporites “novicus"; b: Potomeispontes bhardwajn, c p ^^ r, ' es

globiformis: d: “ Poionieisporites bhardwajii": e: Nuskoispontes sp.; f: Potomeispontes clams . g.

"doubingeriV h: Playfordiaspora crenulata ; i: Lunatisporites sp ; j: Lantvspontes cruciform is: k.

sp.; 1: Densipollenites sp.; m: Divarisaccus latesulcatus ; n: Mosulipollenites circularts, o. Complexisporites

polymorphus-, p: Strialoabieites sp.; q: Densoisporites sp. All pictures: x 400. Toutes figures : x 400.

Source:

276

JEAN BROUTIN ET AL.

IlaurussiaI

EQUATOR

^IRANl> "

LHASA

E. GONDWANA

NW GONDWANA

™ SW LAURUSSIA

C i^Sp

NW GONDWANA

Terrigenous shelf and basins

Deep basins below

or above CCD

Euramerian assemblages

"" + Cathaysian + Gondwanan

"immigrants"

Euramerian assemblages

+ Cathaysian + Gondwanan

"immigrants"

Gondwanan assemblages

+ Euramerian "immigrants"

Gondwanan assemblages

+ Euramerian "immigrants"

Sp = South-Western Spain; M = Morocco

N = Niger (Early-Late Permian)

G = Gabon (Late Permian)

Exposed land

Fluvial and lacustrine

environment

Fluvio-deltaic environment

Evaporitic platform

Shallow platform

Fig. 13.— Geographical and stratigraphical distribution of the analysed Permian palaeofloras, along the transect south-western

Spain - Gabon, plotted on the "late Murgabian” map of Baud et al. , 1993.

Fig. 13 .— Distribution geographique et stratigraphique des paleoflores permiennes analysees le long du transect Espagne du

Sud-Ouest - Gabon, replacees sur la carte "late Murgabian ", Bauds t al., 1993.

Source: MNHN, Paris

THE PERMIAN BASINS OF TIDDAS, BOU ACHOUCH AND KHENIFRA (CENTRAL MOROCCO)

277

PALAEOPHYTOGEOGRAPHICAL CONCLUSIONS

Along the Permian southwestern Spain-Gabon transect (Fig. 13), one can observe:

— during the Late Early Permian, the incoming of Gondwanan elements into the Euramerian floral

province, only up to the Southwestern Spain through North Africa (Gondwanan palynomorphs were also

reported from Early Permian of southern Algeria, DOUBINGER & FaBRE, 1983);

— the progressive southwards extension of Early Permian Euramerian Gymnosperms and

Pteridosperms into the North Gondwana domain.

They are recorded (macro- and microfloras) in the “mid-Permian” of western Africa (Niger) and in

the Late Permian microfloras of central Africa (Gabon).

As demonstrated, and well dated, by the occurrence of Walchiacean megafossil forms in the

continental Oman Gharif palaeoflora, sandwiched by the Sakmarian Saiwan and early Murgabian Khuff

marine Formations, this Early-Late Permian southern phytogeographic band extended Eastwards to the

Arabian Peninsula (BROUTIN et al ., 1995).

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Source: MNHN, Paris

INDEX

Aalenian 51; 53; 145; 154; 157; 158; 167; 171; 176; 177:

185; 190; 197; 201; 204; 218; 225; 230; 244; 248; 251;

252

Aalensis Zone 195

Abathomphalus intermedius 66

Abi Adi 134

Acanthicum Zone 24; 31

acritarchs 41; 44; 221

Acrocylhere dubertreti 226

Acrotheutis mosquensis 22

Actinoceramus (Byrostrina) 102

Actinostromarianina lecompti 140

Actinostromarianina praesalesensis 140

Actostroma damesini 140

Acuticostites acuticostatus 21; 25; 26

Acuticosiites bitrifurcatus 21; 25

Adnatosphaeridium 224

Afghanistan 224

Africa 132; 133; 154; 202; 224; 226; 232; 237; 238; 258;

275;277

Afrocythendea faveolata 225

Agbe 134; 136; 137; 138; 140

Aghbalou 245; 249

Aghdarband 49

Ain Beida 185

Ain Killoun 180; 182; 192; 195

Ain Mirid 195

Ain Ouarka 146; 180; 182: 185: 186; 192: 195; 202

Ait Hani 202; 203; 248

Akchagylian 116; 118; 221

Akmysh 60

Aksu-Dere 98

Aktau 61

Aktubinsk 97

Akusha 96; 103; 105

AI ban i Zone 27

Albian 40; 42; 95; 96; 97; 98; 100; 102; 103; 104; 105;

107

Alborz 123

algae 47; 138; 221; 224; 227

Algeria 146; 147; 167; 180; 192: 193; 197; 200; 201; 203;

204; 205: 206; 222; 277

Algovianum Zone 190; 195

Alisporites lenuicorpus 43

Alocolytoceras dorcadis 184

Alps 76

Altaid-Hercynian orogeny 49

Alveosepta 137

Alveosepta jaccardi 220; 227; 232

Alveosepta jaccardi personata 221

Alveosepta powersi 140

Amaltheus sp. 180

Amhuellerella octoradiata 61

Amijiella amiji 227

Ammobaculites ? sp. 54

Ammobaculites sp. 195

Ammodiscus siliceus 195

ammonite 9; 10; 12; 14; 16; 18; 19; 21; 22: 23: 24: 25; 31

96; 98; 100; 101; 103; 105; 107; 112; 133: 134; 138

140; 143; 146; 147; 157; 162; 167; 171; 176: 177; 180

182; 184; 185; 186; 190; 192; 193; 195; 200; 203; 205

218; 219; 221; 222; 230; 231; 242; 243; 253

ammonoid 36; 37; 39; 44; 46; 49; 51; 53; 59; 60; 218

Amoeboceras 23

Amoeboceras (Amoebites) cf. kitchini 16

Amoeboceras (Amoebites) cricki 24

Amoeboceras (Amoebites) gr. kitchini 16

Amoeboceras (Amoebites) kitchini 24

Amoeboceras (Nannocardioceras) subtilicostatum 19

Amoeboceras (Nannocardioceras) volgae 19

Amoeboceras alternoides 14

Amoeboceras cf. cricki 16

Amoeboceras cf. damoni 14

Amoeboceras cf. freboldi 16

Amoeboceras cf. glosense 14; 23

Amoeboceras cf. koldeweyense 14

Amoeboceras cf. linear am 16

Amoeboceras cf. ovale 14

Amoeboceras cf. talbejense 14

Amoeboceras cf. tuberculatoalternans 16

Amoeboceras gerassimdvi 16

Amoeboceras gr. serration 14

Amoeboceras ilovaiskii 14; 23

Amoeboceras koldeweyense 16

Amoeboceras leucum 16; 23

Amoeboceras sp. 16; 18; 19; 24

Amoeboceras transitorium 14

Amoeboceras tuberculatoalternans 16; 23

Amphisauroides discessus 263

Amydropthychus 226

Anarak 43

Anatolide 123; 128

Anchispirocyclina praelusitanica 227

Angulaticeras gr. dumortieri 186

Anisian 43

Annularia hunanensis 212

Antalo limestone 131; 132; 133; 134: 140; 141; 143

Anti-Atlas 238

Source

280

INDEX

Atitichnium salamandroides 263

Antilebanon 213; 214; 221; 222; 227; 230

Apennines 163; 186

Aporrhais 14; 16

Aporrhais sp. 16

Applanopsis 224

Applanopsis turbatus 224

Applanopsis turbatus Zone 224

Aptian 58; 60; 105; 106; 107

Aptychus 19

Aquitaine 31

Arabia 125; 134; 213; 222; 230: 231; 232

Arabian Peninsula 277

Arabian platform 222; 231

Aratrisporites 43

Araucariaceae 51

Araucariacites australis 51; 216

Arcthoplites 96

Arctic shelf 12

Ardon 214; 216; 217; 218: 224; 225; 227; 230

Argentina 52; 275

Arieticeras sp. 184: 195

Arizona 262

Arkelli Zone 171

Arlit 275

Arnioceras 193

Arnioceras cf. arnouldi 186

Arnioceras cf. flavum 186

Arnioceras cf. speciosurn 186

Arnioceras geometricum 186

Arnioceras miserabile 186

Asher 213; 214; 216; 217

Asia 36; 54; 68

Asphinctites cf. polysphinctus 168

Aspidoceras 19

Aspidoceras caletanum 18; 24

Aspidoceras gr. longispinum 19; 24

Aspidoceras gr. quercynum 19; 24

Aspidoceras quercynum 19

Aspidoceras sp. 19; 24

Aspidoceratids 24

Aspidoceratinae 222

Aspidolitlius parcus constrictus 61

Aspidolithus parcus parcus 61

Assoul 244; 249; 251

Astacolus compressaeformis 56

Astacolus ectypa costata 56

Astacolus sp. 56

Astacolus spp. 41

Astarte 14

Astarte sp. 13

Asteroceras 186; 193

Asteroceras aff. confusum 186; 193

Asteroceras margarita 186

Asteroceras meridionale 186

Asteroceras stellare 186; 193

Asteroceras varians 186

Asturian 258

Ataxioceras (A.) gr. discoidale 140

Ataxioceras (Parataxioceras) gr. polyplocum 140

AtaxOphragmium nautiloides 101

athleta Zone 219; 222

Atlantic 103; 147; 148; 202: 204

Atlas 146; 147; 149; 180; 184; 186; 192: 193; 196; 197;

200; 201; 202; 203; 204; 205; 237; 258

Atlit 217

Aucellina 102

Aulacostephanids 24

Aulacostephanus 24

Aulacostephanus autissiodorensis 19; 24; 31

Aulacostephanus cf. yo 19

Aulacostephanus contejeani 19; 24; 31

Aulacostephanus eudoxus 18; 24

Aulacostephanus kirghisensis 19

Aulacostephanus undorae 19; 24

Aulacostephanus volgensis 19; 24

Aulacostephanus yo 19; 24; 31

Aulacothyris nov. sp. A 180

Aurigerus Zone 167

Australia 52; 275

Autissiodorensis Zone 19; 24

Autun 268

Autunia (Callipteris) conferta 275

Autunian 268; 272; 275

Autuniopsis sp. 268

Aveyroniceras 190

Badenian 84

Bairdia aff. B 225

Bairdia aff. hilda 225

Bajocian 51; 52; 107; 145: 146; 154; 157; 163; 164; 167;

168; 176; 177; 178: 182: 185; 190; 192; 195; 196; 201;

204; 218; 224; 225; 226; 227; 230; 231; 239; 243; 244;

245; 251; 252; 254

bakewellids 45

Bakuriani 114

Baksan River 103

Balanocidaris glandifera 220

Baltic Sea 76

Baltica 79

Barbur 218

Barents Sea 43

Barents shelf 12

Bamea 218; 220

Barremian 58; 59

Bathonian 52; 54; 132; 133; 145; 146; 147; 148; 154; 157;

164; 167; 168; 171; 176: 177; 185; 190; 196; 204; 213;

Source: MNHN, Paris

INDEX

281

218; 219; 224; 225; 226; 227; 230; 231; 239; 240; 245;

249; 252; 254

Bay lei Zone 16

Bechar 204

Beer Yaakov 219

Beersheva 226

belemnite 14; 16; 18; 19; 21; 22; 102; 105

Ben Zireg 197

Beni Bahdel 176; 203

Beni Bou Said 167

Beni Mellal 186; 203

Beni Mishel 157

Beni Ouarsous 160; 162

Beni Snassene Mountains 157

Beni Snouss Kheniis 205

Beni Yala 180; 203

Beni-Bassia 192

Berberids 149

Berriasella richteri 221

Berriasian 25; 29; 58; 59

Bifrons Zone 167; 176; 184; 195:204

Bifurcatus Zone 23

Bikfaya 221

Bimammatum Zone 220

Biscutum 49

Biscutum constcms 58

Bisulcocvpris oertlii 225

bivalve 14: 16; 18; 22; 37; 39; 46; 47; 51; 58; 59; 98; 102;

134; 136: 138; 168: 184: 185; 186; 200; 218; 219; 220:

226:231

Black Sea 76; 112; 121; 123; 124; 125: 128

Blue Nile Bassin 133

Bohemian Basin 98

Bohemian Massif 98

Bolorian 257; 272

Boqer 218; 220; 226

Bositra 176

Bothriopneustes galhauseni 196

Botryococcus 51

Bou Achouch 257; 258; 259: 263; 267: 268; 272

Bou Arfa 192

Bou Dahar 192; 200; 230

Bou Lerfahd 182; 190; 192

Boudjenane 162; 203

Bou/ouggargh 266

braarudosphaerids 59

brachiopod 18; 19; 41; 49; 53; 58; 101; 132; 134; 136;

138; 146; 157; 162; 167; 168; 180; 185; 192; 193; 197;

200; 203; 218; 219; 220; 221; 226; 231

Bremeri Zone 167; 171

Brightia socini zone 220

Brightio sp.222

Britain 12; 27

Brotzenella berthelini 98; 100

bryozoans 219

Buchia 14

Buchia concentrica 18

Buchia sp. 22

Bullatimorphites 171; 231

Bullatimorphites bullatus 219

Bui latus Zone 171

Burgundia 140

Burgundia ramosa 140

Burgundia trinorchii 140

Burmirhynchia 226

Burmirhynchia termierae 168

caadomia 79

Cadomites deslongchampsi 171; 176

Cadomites gr. deslongchampsi 177

Caesarea 219; 220

Calamospora sp. 43

Calculites ohscurus 61

Callialasporites dampieri 52

Callialasporites dampieri zone 52

Callialasporites minus 51; 52

Callialasporites sp. 52

Calliperids 268: 272

Callovian 49; 52; 53; 54; 56: 57; 68; 132; 133; 134; 146;

147; 148; 157; 167; 171; 201; 204: 213; 214: 219; 220;

222; 223; 224; 225; 226; 227; 230; 231: 232

Calloviense Zone 53

C aloceras 146; 185

Cambrian 77

Camerosporites secatus 46

Campanian 61; 65; 66; 68

Campbeliella striata 221

Cannanoropolis spp. 272

Capillirhynchia ardescica 168

Carboniferous 49; 82

Cardiocerartid 23

Cardioceras (Cardioceras) gr. cordatum 14; 23

Cardioceras (Cawtoniceras) tenuiserratum 14; 23

Cardioceras (Maltoniceras) kokeni 14

Cardioceras (Plasmatoceras) popilaniense 14; 23

Cardioceras (Plasmatoceras) tenuicostatum 14

Cardioceras (Plasmatoceras) tenuistriatum 14; 23

Cardioceras (Subvertebriceras) densiplicatum 14; 23

Cardioceras (Subvertebriceras) zenaidae 14; 23

Cardioceras cf. mauntjoi 14

Cardioceras gr. cordatum 23

Cardioceras sp. 14

Cardioceratid 12; 23: 24

Carixian 157; 164; 167; 171: 176: 180; 184; 186: 193;

200; 203; 242; 246; 249

Carmel 218; 219

Carnian 46; 47; 48: 67; 216; 260

Carpathians 76; 81; 113

Source :

282

INDEX

Caspian Sea 36; 112; 121; 123; 124; 125; 128

Caucasus 96; 102; 103; 104; 105; 106; 107; 108; 112; 113;

116; 121; 122: 124; 125; 126; 128

Caumontispliinctes 176

Caumontisphinctes aplous 176; 177

Celcbratum zone 195; 197; 201; 203

Cenomanian 30; 60; 68; 96; 97: 98; 100; 102; 103; 104;

105; 106; 107; 240

Cenozoic 84; 111; 116: 120; 157; 177; 180: 238; 285

Central Asia 49

Central Europe 98

Ceratolithoides aculeus 61

charophytae 45

charophyte 267

Chemarikh 146; 180; 185; 186; 192; 193; 200; 202

Chirkala 61

Chokrakian 116; 118; 121; 125

Chondrites 21; 101; 102; 103; 195

Chott ech Chergui 180

Chougrane 285; 267

Citliarina sokolovae 56

Citharinella spatha 56

Claromontanus Zone 23

ClassopOflis 51

Ctypeina jurassica 227

coccolithes 220

Cochlearites 180

Collinites sp. 195; 197

Collotia discus 171

Collotia sp. 222

Coloptoria 226

Complexisporites polymorphic 268

Compositosphaeridium 224

Conarosia 226

Concavum Zone 190

Coniacian 58; 61; 68; 81; 98: 100; 101; 102

Coniopteris spp. 51

conodonts 37; 67

Contusotruncana fornicata 65

Contusotruncana plummerae 65

Conusphaera mexicana 221

coral 131; 136; 137; 140; 141; 177; 184; 192; 193; 197;

204; 219; 238; 242; 245; 251: 253

Cordaites 262

Cordaites spp. 275

Cordatum Zone 13; 23

Corisaccites alatus 43

Corisaccites stradivarii 39

Corollina 224

Coronatum Zone 219; 222; 227

Cosmetodon sp. 14

Costispiriferina mansfieldi 41

Craspedites 27

Craspedites fragilis 26

Craspedites ivanovi 26

Craspedites jugensis 26

Craspedites kaschpuricus 22; 26

Craspedites krilovi 26

Craspedites kuznetzovi 22; 26

Craspedites milkovensis 22; 26

Craspedites mosquensis 22; 26

Craspedites nekrassovi 22; 26

Craspedites nodiger 22; 26

Craspedites okensis 22; 26

Craspeditesparakaschpuricus 22; 26

Craspedites pseudofragilis 26

Craspedites suhditoides 22

Craspedites subditus 22; 26

Craspedites triptych us 26

Crassiceras gradatum 195

Cremnoceramus rotundatus 100; 102

Crendonites kuncevi 26

Creniceras renggeri 223

Cretaceous 25; 58; 59; 60; 68; 77: 79; 84; 87; 93; 94; 95;

97: 103; 104; 132; 134; 221:227

Cretarhabdus spp. 61

Cribrosphaerella ehrenbergii 61

Crimea 79; 94; 96; 97; 98; 100; 101: 102; 103; 104; 105;

106; 107

Crinalites sabinensis 43

crinoids 14; 136

Crusisaccites spp.272

Ctenostreon (= Lima) palati 185

Ctenostreon palati 185

Culmitzschia (al. Walchia) laxifolia 268

Culmitzschia (al. Walchia) parvifolia 268

Culmitzschia (al. Walchia) speciosa 268

Cunningtoniceras aff. inerme 60

Cutch 226

Cycadopites sp. 46

Cyclagelosphaera deflandrei 58

Cyclagelospltaera margerelii 58

Cyclagelosphaera wiedmanni 56

Cylindralithus serratus 61

Cylindralithus sp. 61

Cymodoce Zone 16; 24; 29

Cytherella ? toarcensis 225

Cytherella bashai 225

Cytherella cf. umbilica 226

Cytherella index 225

Cytherelloidea atlantolevantina 226

Dactylioceras (Eodactylites) gr. mi labile 184

Dactylioceras IOrtliodactylites) sp. 184

Dades 245

Daghanirhynchia 226

Daghestan 96; 103

Dalmatia 43

INDEX

283

Danakil Alps 133; 140; 143

Dapsilidinium? deflandrei 224

dasycladacean 47

Daya 214; 218; 224; 225; 230

Dcbdou 180

Deglene 167; 168; 171: 176; 177; 201

Dehornella crustans 140

Dehornella harrarensis 140

Demonense Zone 186; 195

Densiplicatum Zone 14; 23

Densoisporites 43

Densoisporites complicatus 43

Densoisporites nejburgii 43; 44

Densoisporites playfordii 43

Densoisporites spp. 41

Dentalina 195

Dentalina nodigera 195

Dentalina obscura 195

Dentalina oppeli 56

Dentalina sp. 56

Dentalina terquemi 195

Dentalina turgida 56

Dentaliutn sp. 14

Desmosphinctes cf. niniovnikensis 16

Devonian 82; 86

Devorah 213; 217; 221; 230

Dichadogonyaulax 224

Dichadogonyaulax sellwoodii Zone 224

Dichophyllum cf.Jlabellifera 268

Dicraloma 14

dinocysts 53; 221; 224

dinoflagellate 53; 220

Diotis 186

"Diotis" janus 186

Dipoloceras cristatum Zone 60

Divarisaccus latesulcatus 272

Djebel Antar 180

Djebel Chemarikh 186; 192

Djebel es Sekika 157

Djebel Fillaoussene 157

Djebel Gorine 157

Djebel Grouz 180; 192; 193

Djebel Guetob Moulay Mohammed 184

Djebel Guettaf 182; 184; 196

Djebel Hafid 180

Djebel Kerdacha 192

Djebel Melah 185; 186

Djebel Reha 184

Djebel Selib 171

Djebel Sfissifa 182

Djebel Souiga 185

Djebel Tifkirt 185

Dobrogea 76; 77; 79

Dogger 237; 239; 247; 250

Dolikephalites gracilis 171

Dolnapa 37; 38; 45

Domerian 146; 157; 171: 176; 177; 180; 184; 185; 193;

195; 200; 201: 203: 204; 243; 246

Dorikranites 44

Dorset 30

Dorset Portland 25

Dorsoplanites dorsoplanus 21; 25

Dorsoplanites panderi 21; 25

Dorsoplanites rosanovi 26

Dorsoplanites serus 26

Dubky 12; 18; 19; 24

Dzhamansauran 49; 58

Dzharmysh 49; 51; 52; 53; 54; 58

East European Platform 120

echinid 101; 196

Echysoria 226

Egypt 214; 216; 220; 221; 225; 226; 232

Eiffellitluis eximius 61

Eiffellirhns turriseiffelii 61

Ein Qinia 221

Ektyphocythere aardaensis 225

Ektyphocythere bucki 225

Ektyphocythere cf. vitilis 225

Ektyphocythere shulamitae 225

Ektyphocythere zerqaensis 225

Ektyphocythere zoharensis 225

El Abed 167

El Harchaia 182; 185

Eligmus 226; 231

EUipsoidictyinn 224

Emaciaticeras sp. 184

Emaciatum Zone 176; 190

Emileia catamorpha 176

Emileia cf. brocchi 192

Emileia polyschides 176

Emmetrocysta 224

Endikurgan 60; 61: 65

Endosporites papillatus 39; 43; 44

Energlynia 224

England 30; 31; 98: 106; 220

Entolium sp. 13; 14

Enzonalasporites vigens 46

Eocene 116; 120; 123; 128; 132; 157

Eodactylites 192

Eodactylites spp. 177

Eodentata Zone 105

Eoguttulina sp. 56

Epiplosphaera reticulospinosa Zone 224

Epistomina sp. 56

Epivirgatites bipliciformis 21; 26

Epivirgatites lahuseni 26

Epivirgatites nikitini 22; 26; 27

284

INDEX

Epophioceras 193

Epophioceras sp. 186

Eprolithus Jloralis 61

Eretmonia 272

Ermoceras 184; 192; 231

Errachidia 146; 249

Estherids 44

Ethiopia 131; 132; 134

Euaptetoceras sp. 190

Euaspidoceras douvillei 223

Euaspidbceras sp. 36; 223

Euaspidoceras subbabeanum 223

Euaspidoceras subcostatum 223

Eucytlierura oxfordiana 226

Eudoxus Zone 18; 24; 30

Eumorphotis 37

Eunerinea 219

Europe 43; 52; 54; 60; 78; 93; 95; 98; 100; 101; 103; 106;

107; 125; 203; 204; 206; 219; 222; 223; 224; 226; 227;

230; 232; 275

European platform 76; 78; 81

Eurysites 226

Everticydammina 137

Everlicyclammina virguliana 140

Evoluta Zone 24

Exesipollinites tumulus zone 52

Exophthalmocythere? kidodensis 225: 226

Fabanella ramonensis 225

Falsopalmula inaequiiateralis 56

Fascipteris cf. robusta 272

Fastigatocythere bakeri 225

Fcndi 197

Fernane 167; 168

Feysia minutifolia 268

Figuig 146; 147; 182: 184; 192; 193; 195; 197; 200; 201;

202; 203

Flabelloeyelolina reissi 2 19; 227

Fletcherithyris margaritovi 41

foraminifer 37: 39; 41; 45; 46; 49; 53; 56; 61; 65; 66; 68;

98; 100; 101; 103; 107; 133; 134; 136; 137; 138; 140;

143: 186; 193; 195; 214; 218; 220; 221: 227; 231

Fore-Caucasus III; 112; 113; 114; 118; 122; 124; 125;

128

Forresteria petrocoriense 100

France 98; 106

Frechiella sp. 1 76

" Frondicularia ” ex gr. elegantula 39

Fuciniceras sp. 171; 195

Furloceras 185

Furloceras erbaense 171

Furloceras evolution 17 1

Ga'ash 216; 218

Gabon 257; 272; 275; 277

Galaticeras cf. aegoceroides 186

Galilee 213; 218; 221; 227; 230; 232

Gansserina gansseri Zone 66

Gardenasporites 268

Garniericeras catenulatum 22; 26

Garniericeras interjection 26

Garniericeras subclypeiforme 22: 26

gastropod 14: 16; 46; 136; 138; 219; 221

Gavelinella cenomanica 98; 100

Gavelinella cf. vombensis 100

Gavelinella moniliformis 100

Gavelinella moniliformis Zone 102

Gavelinella praeinfrasantonica 100

Gebel El-Maghara 225; 226

Gebel Maghara 219; 220; 221; 225; 262: 263

Genizinita ex gr. crassata 56

Gerar 219

Germany 31; 98; 104; 106

Gevar Am 213; 214; 219: 220; 221: 230

Gharif 277

Gibbirhynchia curviceps 180

Gilmoreichnus 263

Gilmoreichnus brachydactylus 263

Ginkgophytes 268; 272

Ginkgophytopsis kidstonii 272

Glaucolithus Zone 27

Gleviceras gr. doris 186

Globigerinelloides 65

Globigerinelloides asper 65

globigerinelloidids 65

Globirhynchia 226

Globirhynchia crassa 226

Globorotalites hangensis 100; 102

Globotruncana aegyptiaca Zone 66

Globotruncana ventricosa 65

Globotruncana ventricosa Zone 66

Globotruncanella havanensis Zone 66

Globotruncanella pschadae 66

Globotruncanita subspinosa 66

Globuligerina sp. 56

Glochiceras 26

Glochiceras ( Paralingulaticeras ) cf. lithographicum

Glochiceras (Paralingulaticeras) cf. parcevali 19

Glochiceras aff. lithographicum 25

Glochiceras aff. parcevali 25

Glochiceras sp. 19; 21; 25

Glomospira sp. 227

Glosense Zone 14: 23; 28

Glossopterids 272

Glossopteris anatolica 272

Glossopteris communis 272

Glyptocythere huniensis 225

INDEX

285

Glyptogatocythere magharaensis 225

Glyptogatocythere malzi 225

Gondolella cf.jubata 39

Gondwana 133:200; 231

Gonolkites 167

Gordonispora fossulata 43

Gordonispora sp. 43

Golan 227

Gorine 164

Gorny Mangyshlak 36; 39; 53; 57; 58; 61; 66

Gorodische 12; 21; 26; 29

Goulmina 245; 251; 253

Gracilis Zone 168; 171; 201

Gradala Zone 171; 176; 177; 184; 190; 203; 205

Gradatum Zone 195

Grammatodon sp. 14

Grammoceras 218

“Grandes Rosalines” ex gr. Marginot runeana

coronatarenzi 100

Graphoceratids 171

Gravesia 12; 26

Gravesia cf. gigas 19; 25

Gravesia cf. gravesiana 19

Great Balkhan 94; 97; 102; 103; 105; 106

Great Caucasus 103; 112; 113; 114; 120; 121; 123; 124;

125; 126;128

Grebeispora concentrica 43

Greenland 12; 52

Grojec 80

Gryphaea dilatala 14

Guadalacanal 259

Guercif 157

GuettaV 184; 185

Gutnicella gr. cayeuxi 227

Guttapollenites harmonious 43

HagereSelam 134

Haifa 213; 217; 218: 219; 221; 224; 225; 230

Halal 214; 216; 217; 218; 219; 220; 227

Haluza 221: 226

Hamakhtesh Hagadol 214; 219; 220; 222; 225; 227

Hammatoceras 146; 171; 177:205:206

Hammatoceras roubanense 146; 171; 177; 205; 206

Hammatoceras speciosum 206

Hanimatoceratids 205

Haploceras aff. elimatum 25

Haploceras cf. elimatum 19

Haploceras sp. 21

Haplophragmoides sp. 56

Harar 140

Hassi Ben Khelil 203

Haurania 218

Haushi-Huqf 272

Hauterivian 59; 221:230

Hazon 221; 226

Hebrides 204

Hecticoceras (Brightia ) aff. s alvadorii 222

Hecticoceras (Chanasia) michalskii 171

Hecticoceras ( Hecticoceras) boginense 171

Hecticoceras <H.) posterium 171

Hecticoceras (Kheraites) ferrugineus 222

Hecticoceras ( Lunoloceras ) cf. fan re i 56

Hecticoceras (Putealiceras) douvillei 222

Hecticoceras (Putealiceras) intermedium 222

Hecticoceras bonarelli 223

Hecticoceras cf. guthei 223

Hecticoceras chatillonense 223

Hecticoceras coelatum 223

Hecticoceras kautzschi 223

Hecticoceras schumacheri 223

Hecticoceras separandum 223

Hecticoceras socini 223

Hecticoceras socini Zone 223

Hecticoceras socium 223

Hecticoceras solare 223

Hecticoceras syriacum 223

Hecticoceratinae 222

Helez 214; 218; 220; 227:230

Helvetoglobotruncana Helvetica 100

Hercynian 113; 258; 260; 263

Hermon 213; 214; 218; 219; 220; 221; 222; 223; 224; 225;

226; 227; 230

Hesperithyris renierii 184

Hesperithyris sp. 180

Hesperithyris termieri 180

heterohelicids 65

Heterohelix 65

Heterohelix globulosa 65; 66

Heterohelix labellosa 66

Hettangian 52; 146; 180; 185; 193; 197; 200; 202; 239;

240; 241

Heu River 103

Hibolites sp. 14

Hidoceratids 195

High Atlas 184; 186; 192: 200; 201; 202: 203: 204; 237:

238; 239; 240; 241; 242; 243; 245; 247; 249; 251; 252;

254

High Plains 146; 147; 149; 177; 1180; 184; 197; 202; 203;

204; 205

High Plateaux 177; 180; 197:203

Hildoceras 167

Hildoceras angustisiphonatum 195

Hildoceras bifrons 195

Hildoceras gr. semipolitum 195

Hildoceras snoussi 171

Hildoceras sublevisoni 195

Holcophylloceras 171

Holcophylloceras sp. 168

Source:

286

INDEX

Holcophylloceras zignodianum 171

Holy Cross Mountains 75; 76; 77; 78; 79; 83; 84; 85; 86;

87; 88; 89; 90

Homerocylhere hennonensis 226

Homoeorhynchia lifritensis 167

Humboldt Range 41

Humphriesianum Zone 157; 176; 201; 204

Hursonia 226

Hutsonia adunata 220; 221; 226

Hybonotum Zone 26

Hyloidichnus 262

Hypacanthoplites 105

Hysteroceras orbignyi 96

Hysteroceras orbignyi Zone 105

Hystrichogonyautax 224

Icthyosaurus 21

Iffer 249

llowaiskya klimovi 19; 25

Howaiskya pavida 19; 21; 25

llow aiskya pseudoscythica 21; 25

llowaiskya schaschkovae 21; 25

llow aiskya sokolovi 19; 21; 25

Imilchil 244

India 134; 226

Indian Ocean 133

Indol-Kuban 112

Indosphinctes gr. patina 171

Induan 39: 43: 48

Infraparkinsonia sp. 177

Inmar 213; 214; 218; 224; 225; 230; 231

Inoceramid 93:98; 100: 101: 103

Inoceramus costellatus 102

Inoceramus costellatus Zone 102

Involutina liassica 186

Iran 43; 224

Iranian Block 68

Ischyosporites spp. 52

Isobythocypris oval is 225

Israel 213; 214; 217; 219; 221; 222; 224; 225; 226; 227;

230;232

Jebel Aberdouz 251: 252

Jcbel Grouz 197

Jebel Haimeur 193; 195; 202

Jebel Masker 214; 251

Jebel Nador 180: 184: 197

JorfHenndia 167

Judea 218; 220; 227; 230

Jugasporites sp. 275

Jurassic 9: 10: 12; 25; 27: 30; 35; 36; 47; 51; 52; 53; 54;

68; 75; 79; 81; 83: 89; 90; 113; 120; 131: 132; 134;

145: 147; 154; 157; 163; 167: 178; 180; 182; 184; 185:

192; 200; 202; 204; 213: 214; 218; 219; 221; 222; 224;

225; 226; 227; 230; 231; 232; 237; 238; 239; 240; 252

Kachpurites fulgens 22; 26

Kachpurites subjulgens 22; 26

Kamenyi Ourag 18

Karaduan 45; 46

Karatau 36; 37; 38; 44; 45; 49

Karatauchik 36; 37; 39; 44: 45

Karmon 213; 230

Karpinsky swell I 14

Karroo 132; 134

Kashpir 12; 21; 22: 29

Kazakhstan 35

Kazakhstanites 43

Kazanian 275

Kenya 226

Kerberites 27

Kerberus Zone 27

Kerdacha 192

Kfar Darom 219

Kheneg Grou 200; 201

Khenifra 257; 258; 259; 266; 267; 268; 272

Kheraiceras bullatuni 167

Khuff 277

Kielce 78

KiUanina 227

Kilianina sp. 218

Kimmeridge 9; 30

Kimmeridgian 9; 10; 12; 16: 18; 23; 24; 26: 29; 30; 31; 52;

27; 58; 59: 131; 132; 134; 140; 143: 147; 154; 202;

205; 214; 220; 221; 226; 227; 230; 232

Kinkelina kadeshensis 225

Kissufim 219

Klausipollenites schaubergeri 275

Klimovi Zone 19; 25; 26

Knoxisporites 272

Koenigi Zone 54

Kohal 226

Kokhav 220

Korystocysta 224

Kosmoceras annulatum 56

Koudiat el Hai'ddoura 146

Koudiat el Haifa 176; 195

Krauselisporites 43

Krauselisporites sp. 39; 43

Ksour 147; 149; 167; 182; 185; 196; 201:204

Ksour El Harchaia 167

Ksour Mountains 146; 147: 168; 180: 184; 186; 192; 193;

203;204

Kugusem Scarp 44

Kuibyshev reservoir 12

Source MNHN, Paris

INDEX

287

Kuma 105

Kuma High 114

Kungurian 272; 275

Kugusem scarp 44

Kurnub 214; 218; 219; 227

Kurnubia (K.) palastiniensis 227

Kumubia (K.) variabilis 227

Kumubia bramkampi 227

Kumubia cf. wellingsi 227

Kumubia gr. palastiniensis 219

Kumubia palaistinienis 140

Kumubiella compressa 222

Kutchithyris 226

Labirintodonts 44

Labyrinthina recoarensis 184

Ladinian 46; 67

Laevaptychus 19

Laevicythere sp. 225

Laeviuscula 231

Lagena ex. gr. laevis 56

Lamberti Zone 56; 219; 222

“Lamberti” Zone 222

Lamplughi Zone 25

Laramide 86; 87; 88; 89: 90

Laugeites aenivanovi 21; 26

Laugeites stschurowskii 21; 26

Lebanon 213; 22118; 221; 226; 227; 230

Leioceras ( Cypholioceras) cf. comptum 190

Lenticulina aff. russiensis 56

Lenticulina aff. sumensis 56

Lenticulina brueckmanni 56

Lenticulina cf. tumida 56

Lenticulina comae 56

Lenticulina compressaefonnis 56

Lenticulina d'orbignyi 195

Lenticulina deslongchampsi 195

Lenticulina ex gr. goettingensis 39; 41

Lenticulina hyalina 56

Lenticulina munsteri 195

Lenticulina sp. 195

Lenticulina spp. 56

Lenticulina subalata 195

Lenticulina sublaevis 195

Leptolepidites spp. 52

Leptospbinctes (Cleistosphinctes) cleistus 171

Leptosphinctes (L.) davidsoni 171

Leptospbinctes ( L) perspicuus 171

Leptosphinctes cf. perspicuus 177

Lesser Caucasus 103; 107: 111

Levant 213; 214; 224; 226; 227

Levantinella egyptiensis 218

Levisoni Zone 167; 176; 201; 203

Leymeriella ( Leymeriella) 105

Liassic 98; 157; 192: 193; 197; 216; 217; 225: 227; 230;

231; 238; 239; 242; 245; 249; 250; 251; 253; 254

Libya 224

Lidgettonia 272

Limitisporites sp. 275

Limognella sp. 227

Lingula sp. 18

Lingulina ex gr. belorussica 56

Lingulina tenera 195

Lingulogavelinella globosa 98; 100

Liospiriferina praerostrata 197

Lioslrea sp. 53

Lirellarina 226

Lithastrinus septenarius 61

Lithiotis 180; 200

Lithraphidites carniolensis 58

Lituotuba ? sp. 39

Lobatannularia aff. L. sinensis 212

Lobothyris subpunctata 180

Lodeve 263

Lodevia (Callipteris) nicklesii 275

Lodevia nicklesii 268

Lomonossovella blakei 268

Lomonossovella lomonossovi 21: 26

“ Lomonossovella ” lomonossovi 27

Loripes 19

Loripes sp. 16

Lotharingian 238; 239; 242; 245; 249; 250: 251; 252

Lower Saxony 104

Lublin 79

Lucianorhabdus cayeuxii 61

Lucianorhabdus maleformis 61

Ludwigella cf. arcitenens 190

Lueckisporites singhii 43

Lueckisporites virkkiae 275

Lunatisporites noviaulensis 39; 43

Lunatisporites pellucidus 43

Lunatisporites sp. 43; 268

Lunatisporites spp. 39; 43

Lundbladispora 43

Lundbladispora brevicula 43

Lundbladispora echinata 43

Lundbladispora sp. 43

Lunuloceras 171

Lusilanian Basin 192; 193; 206

Lyelli Zone 105

Lyelliceras 105

Lysogory 78

Lytoceras adeloides 176

Lytoceras eudesianum 171

lytoceralids 107

288

INDEX

Maastrichtian 65; 66; 68; 84

Macrocephalites 167

Maculatisporites sp. 43

Madagascar 134

Maghara 213; 227

Maghreb 147; 186; 193; 200; 203; 204

Maikopian 111; 116; 118; 120; 121; 124; 125; 127; 128

Maiz 192; 195

Majdal Shams 213; 214; 220; 222; 223; 225; 230; 232

Makariev 12; 13; 16; 23; 24; 28

Makhtesh Qatan 218

Makhtesh Ramon 214; 225; 227

Malletia sp. 18

Malopolska Massif 79

Mancodinium semitabulatum 52

Mandelstamia hirschi 225

Mangliastia 2 18

" Mangashtia ” egyptiensis 227

Mangyshlak 35; 36; 44; 48; 52; 54; 57; 67; 68; 94; 97; 98;

100; 101; 102; 103; 105; 106; 107

Manivitella pemnuitoidea 61

Mantelliceras 100

Manych 116

Marginotrmcana 102 ;

Marginotruncana coronatarenzi 100

Marginulina batrakieformis 56

Margimdina mimita 56

Marginulinopsis aff. procera 56

Mariae Zone 220; 223; 232

“Mariae” Zone 220

Malmor 214; 219; 222; 224; 225; 230; 231

Mcchraa Ben Abbou 258; 267

Medilerranean Sea 147; 200

Megalodontids 176; 177; 200; 201; 203

Mekele 134; 140

Mekele oullier 131; 132; 133; 134; 140; 141

Melah 182; 185

Meteagrinella 14; 18

Mellala 162; 203

Mendicodinium umbriense 52

Meneghinii Zone 176

Meotian 116; 121

Merlaites gr. allicarinatus 177

Mesozoic 25; 35; 36; 66; 68; 75; 76; 83; 85; 86; 88; 89;

90; 120; 133; 180; 197

Meyendorffina bathonica 227

Miasto 79

Micrantolithus hoschulzii 58

Micrantolithus oblitsus 58

Micfhystridium sp. 44

Micromphalites 222; 231

Micromphalites pustuliferus 219

Micropneumatocythere laevireticulata 225

Microrhabdulus decoratus 61

Micula decussata 61

Millioudodinium 224

Millioudodinium nuciformis Zone 224

Mimci 12; 16; 24; 29

Miocene 77; 84; 87; 111; 116; 121; 125; 128

Mirosphinctes aff. robyi 223

Mirosphinctes sp. 223

Mishhor 213; 214; 224; 227; 231

Mleta Plain 157

modiolids 45

Modiolus 51

mollusc 132

Monoceratina 225

Monoceratina stimulea 226

Monoceratina striata 225

Montlivaltia 177

Moroccan Meseta 204

Morocco 146; 147; 157; 167; 177; 197; 203; 204; 205;

206; 237; 239; 257; 258; 266; 267;

Morphoceras 171

“Morplioceras ” aff. pingue 168

"Morphoceras” parvuin 168

Morphoceras (Ebrayiceras?) parvum 168; 176

Morphoceratid 168

Mortoniceras inflation 96

Morioniceras inflatum Zone 105

Moscow 28

Moscow basin 10

Moulouya 239; 251

Mount Hermon 214; 219; 220; 223

Mountain Crimea 96; 97; 103; 105; 106; 107

Mourhal 197

Mrit-Khouabi 195

Munster Basin 104

Murchisonae Zone 190

Murgabian 277

Mutabilis Zone 24; 30

Myophoriopsis gregariodes 47

Mytiloides hattini 101

Mytiloides hercynicus 102

Mytiloides hercynicus Zone 100

Mytiloides incertus Zone 102

Mytiloides labiatus Zone 100; 102

Mytiloides mytiloides Zone 100

Mytiloides hercynicus - Inoceramus apicalis - Inoceramus

lamarcki Zone 102

Mytilus (Falcimytilus) nasai 47

Nahar Sa'ar 213; 214; 221; 225; 226; 230

Nakhichevan 113

Namurian 275

Nannoceratopsis gracilis 52; 53

Nannoceratopsis pellucida 224

INDEX

289

Nannoceratopsis spiculaia 53

nannoconids 59; 61; 65

Nannoconus dauvillieri 65

Nannoconus farinacciae 61

Nannoconus minulus 61

Nannoconus mullicadus 61; 65

Nannoconus spp. 61; 65

Nannoconus steinmannii minor 58

nannofossil 53; 56; 58; 60; 61; 66; 68; 133; 134; 141; 143

Nannogyra sp. 16

Nannolytoceras tripartitum 168; 176

nannoplancton 218; 219; 221

Nastoria 226

Naumovaspora striata 43

Nautiloculina oolithica 140

Negev 213; 214; 218; 219; 220; 221; 224; 225; 227; 230;

232

Neocardioceras juddi 100

Neochetoceras 26

Neochetoceras aff. steraspis 25

Neochetoceras cf. steraspis 19

Neochetoceras sp. 19

Neospathodus ahruptus 39

Neospathodus cf. N. brevissimus 39

Neospathodus homeri 39

Neospathodus symmetricus 39

Neostlingoceras 100

Neo-Tethys 230; 232

Neotethys 237

Nerineacea 231

Netherlands 52

Nevada 43

New Zealand 124

Niger 257; 275; 277

Nikitini Zone 21; 25; 26

Nilssonia spp. 51

Niortense Zone 171; 176; 177; 182; 190; 197:201

Nil-'Am 213

Niram 214

Nirim 219

Nodiger Zone 22; 25; 26; 27; 29

Nodosaria aff. hoae 39

Nodosaria aff. pseudoprimitiva 39

Nodosaria cf. ordinata 39

Nodosaria cf. shablensis 39

Nodosaria ex gr. oxforea 56

Nodosaria hoae 39

Nodosaria sp. 39

Nodosariids 186

Norian 47; 48

Normannites 176

North America 103

North Sea 10; 30; 31: 163; 204

northern Canada 12

northern Caucasus 94; 96; 102; 103; 105; 106; 107

Nowe Miasto-Ilza 79; 80: 81; 83; 89; 90

Nucula 102

Nuculoma sp. 16

Nuculoma sp. ind. 16

Obtusum Zone 186; 193

Oecotraustes cf. westermanni 171; 176; 177

Oecotraustes scaphitoides Zone 223

Olenekian 39; 454; 45

Oligocene 116; 120; 121; 123; 124; 128

OUgocythereis aff .fullonica 225

Oligocythereis irregularis 226

Oman 134; 277

Opalinum Zone 53; 160: 176; 190; 201; 204

Ophthalmidium sp. 46

Ophthaltnidium strumosum 56

Opisoma 180: 197

Oppelia pouyannei 171; 176; 177

Oppressus Zone 25; 26

Oran 148; 157; 177

Oran High Plains 147; 177; 197; 202; 203; 204

Oraniceras 171

Oraniceras hamyanense 167; 185

Orbitammina elliptica 227

Orbitopsella aff. praecursor 227

Orbitopsella dubari 184

Orbitopsella praecursor Zone 227

Orbitopsella primaeva 217; 227

Ordovician 266

Orthaspidoceras lallierianum 9; 31

Orthaspidoceras liparum 24

Osperlioceras 171

Ossa-Morena 272

ostracod 39; 180; 214; 218; 219; 221; 225; 226

ostreid 59

Otoites 231

Otoites cf. sauzei 192

Otovicia hypnoides 268

Otpan 37; 39

Ouchbis 251

Oued el Hallouf 195

Oued Melah 167

Oued Oum Rbia 268

Oujda 157; 167; 177; 180.206

Ovalipollis pseudoaUuus 46

Oxfordian 10: 12; 13; 14; 23; 28; 30; 35; 56; 57; 131:

1332; 134: 140; 143; 146; 154; 168; 171; 201; 202:

204; 213: 218; 219; 220; 221; 222; 223; 224; 226; 227:

230:232

Oxycerites yeovilensis 168

Oxynotum Zone 186

Oxytoma sp. 14

oyster 16; 53; 59: 136

- - Sautes :

290

INDEX

Pachyerymnoceras kmerense 22

Pachyerymnoceras levantinen.se 222

Pachyerymnoceras sp. 222

Pcichy tlieutis panderiana 14

Pakistan 134

Palaeocene 58; 61; 74; 83; 120

Palaeodasycladus mediterraneus 184

Palaeogene 36; 76; 84; 120

Palaeo-Tethys 67

Palaeozoic 49; 67; 68; 76; 77; 78; 79; 83; 86; 90; 113; 114;

120; 132; 133; 157; 167; 168; 177; 238; 240

Paleopfenderina salemitana 218; 227

Pallasioides Zone 30

Paltarpites gr. paints 177

Paltarpites sp. 184

Paltechioceras 193

Paltechioceras nov. sp. 186

Paltechioceras boeliini 186

Paltechioceras tardecrescens 193

Panderi Zone 21; 25; 27; 29

Paracraspedites oppressus 26

Paracraspedites sp. 22

Pararasenia cf. hybridus 24

Pararasenia hybridus 18

Paratethys 120; 121

Parathyridina mediterranea 180

Parawedekindia 201 ;

Parawedekindia spp. 171

Pareodinia halosa 53

Paris Basin 31

Parkinsonia 51

Parkinsonia (Gonolkites) convergens 168

Parkinson ids 176

Partitisporites spp. 46

Partschiceras gr. viator 176

Parvocysta 53

Parvocysta ? tricornuta 56

Parvocysta nasuta 53

Patinasporites densus 46

Pavlovia pavlovi 21; 25

Peceneaga-Camena fault 76

Pecopteris chihliensis 272

Pecopteris latinervosa 272

Pectinatites aff. pectinatus 25

Pectinatites ianschini 21; 25

Pectinatites tenuicostatus 21; 25

Pectinatus Zone 30

Pediastriwn 51

Peltaspermum martinsii 268

Peltoceras solidum 219; 222

Peltoceras sp. 56; 133; 222

Peri-Caspian 95; 97; 98; 103; 105; 106; 107

Perisphinctes {Arisphinctes) gr. plicatilis 14; 23

Perisphinctes be mens is 223

Perisphinctes sp. 14; 16

Perisphinetidae 14

Perisphinctids 12; 18; 24

Perisphirictinae 222

Permian 38; 49; 76; 77; 79; 80; 81; 82; 83; 89; 90; 120;

257; 258; 259; 260; 262; 263; 266; 267; 268; 272; 275;

277

Perth Basin 52

Pfenderina gr. trochoidea 133

Phanerozoic 76

Phylloceras 171

phylloceratids 107; 171

Phylloceratinae 222

Phyllotheca spp. 272

Physodoceras neuburgense 25

Piarorhynchella mangyshlakensis 41

Pictonia 24

Pictonia baylei 16; 31

Pictonia densicostata 16; 31

Pilica River 80

Plain Crimea 96; 97; 103; 107

Planiinvoluta carinata 45

Planiinvoluta ? sp. 39

Planisepta compressa 184; 193

Planisphinctes sp. 168

Planolites 138

Planula Zone 23

Planularia colligata 56

Planularia contracta 56

Planularia sp. 56

Planularia spatulata 56

Planularia subcompressa 56

Planularia tricarinella 56

Platypleuroceras gr. brevispina 195

Pleisiosaurus 2 1

Plenus Zone 100

Plesechioceras 193; 200

Plesechioceras cf. delicatum 186

Pleuroceras 177

Pleuroceras solare 176: 190

Pleuromeia 38

Pleuromeia sternbergii 44

Pleuromia sp. 13

Pleurotomaria sp. 14

Plicatilis Zone 23

Plicatipollenites gondwanensis 212

Plicatipollenites spp. 272

Pliensbachian 52; 134; 145; 154; 167; 176; 180; 184; 192;

193; 195; 197: 200; 203; 213; 217; 224; 227; 231

Pliocene 263

" Podagrosites" gr. aratum 184

Polish Trough 76; 79; 81; 83: 89; 90

pollen 51; 268

Polymorphitids 195

Polymorphum Zone 177; 184; 201; 203

INDEX

291

Polystephanephorus 224

Polystephanephorus calathus Zone 224

Pontian 121

Pontides 123

Porpoceras sp. 133

Portlandian 25; 27; 31

Portugal 192; 193; 206; 224

Polonieisporites 268

Praeactinocamax plenus 98

Praekurnubia 221

Praekurnubia crusei 221

Praeschuleridea hornei 225

Praeschuleridea inmarensis 225

Prccambrian 76; 78; I 13

Precaueasus 41

Prediscosphaera spp. 61

Preplicomphalus Zone 25; 27

Primitivus Zone 25

Procerites subprocerus 168

Prodactylioceras sp. 184; 195

Progonocy there aff. parastilla 225

Progonocy the re honigsteini 225

Prohecticoceras (Zieteniceras) pseudolunula 171

Promillepora pervinquieri 140

Properisphinctes sp. 223

Proto-Atlantic 232

Protoblechnum sp. 272

Protoblechnum wongii 212

Protocardioceras cf, praecordatum 56

Protodiceras 180

" Protodiceras" sp. 180

Protogrammoceras 186

Protogrammoceras celebratum 171; 180; 195

Protogrammoceras gr. dilectum-pseudodilectum 186

Protogrammoceras gr. volubile-pantanelii 186

Protogrammoceras isseli 171

Protogrammoceras sp. 195

Protohaploxypinus limpidus 43

Protohaploxypinus sp. 43

Pseudobrightia 222

Pseudobrightia s. st. 222

Pseudobrightia sp. 219; 222

Pseudoclypeina 218; 227

Pseudocyclammina sp. 140

Pseudogrammoceras 190

Pseudogrammoceras pinnai 190

Pseudogrammoceras subregale 184; 190

Pseudoscythica Zone 21; 25

Pteridophytae 51

Ptychophylloceras 171

Ptychophylloceras sp. 140

Ptylophyllum spp. 51

Punctatispontes fungosus 43

Purbeck 25

Purpuroidea 2 19

puzosiids 107

Pycnoria 226

Qeren 214; 218; 219; 220; 221; 224; 226; 230

Quadrum gothicum 61

Quadrum sissinghii 61

Quadrum trifidum 65

Quaternary 111; 113; 116; 120; 121; 125; 128; 260

Quenstedoceras cf. praelamberti 56

Quenstedoceras sp. 56

Quinqeloculina sp. 56

radiolaria 182; 186; 193; 202

radiolarian 56; 65; 66

Radomsko 87; 88; 89

Radotruncana calcarata Zone 66

Raistrickia 212

Raknetel Kahla 190; 192; 204

Ramon 217; 218

Rasenia 24; 31

Rasenia cf. cytnodoce 16

Rasenia cf. uralensis 16

Rasenia gr. cytnodoce 24

Rasenia gr. uralensis 24

Rasenia sp. 16

Rastellum 58

Ravva Mazowiecka Basin 81

Regulare Zone 16; 23

Reha 185

Rehmannia (Rehmannia) spp. 171

Reineckeia nodosa 222

Reinhardtites anthophorus 61

Reinhardtites levis 61

Renggeri Zone 220

Retrocostatum Zone 167

Reussella kelleri 102

Rewanispora 43

Reynesoceras 190

Reynesoceras gr. indunense 184

Reynesocoeloceras sp. 195

Rhachiphyllum schenkii 268

Rhaetian 145; 180; 200; 227

RharRoubane 147; 167; 176; 177; 192; 201; 203; 205

Rhipidopsis spp. 272

Rhynchonella assymetrica 226

Rhynchonelta fornix 226

•' Rhynchonella ” moghrabiensis 180

Rhynchonella nobilis 226

Rhynchonella versabilis 226

rhynchonellid 14; 185; 226

RhynchonelloideUa sp. 53

Rhyzocorallium 138

292

Rich 238; 242; 244; 251; 252

Rif 200

Rif-Tell 146; 148; 204

Ringsteadia 23

Ringsteadia cf. frequens 16

Ringsteadia cuneata 23

Ringsteadia frequens 23

Rio Viar 259; 272

Rioni 112

roissyanum Zone 102

Romania 76; 77

Rosenkrantzi Zone 16; 23

Rosh Pinna 218; 231

Rotalipora appenninica 98

Russia 53; 220

Russian Platform 9; 10; 12; 23; 24; 25;

Rutlandella transversiplicata 225

Ryasan 96

Ryazanian 22

Ryazinites Zone 59

Saalian 258

Safa 219; 230; 231

Sahara 147; 149; 177; 178; 180; 184;

202; 203; 204

Saida Mountains 167; 192

Sakmarian 275

Salima 221; 226

Samaria 214

San Nicolas del Puerto 259

Santonian 61; 107

Saracenaria cornucopiae 56

Saracenaria inclusa 56

Saratov 96

Sarmatian 116; 118; 121; 125; 128

Satorina apuliensis 227

Saudi Arabia 225; 226

Sauzei Zone 201; 204

Schizoria 226

Schloenbachia 100

Schlotheimiids 186; 193

Schrammeni Zone 105

Schuleridea 226

Schweizerisporites sp. 272

Scythian Platform 94; 103; 113; 114

Sekika 157; 164; 201

Selliporella donzellii 227

Semenoviceras 68

Semenoviceras litschkovi 60

Semenoviceras litschkovi Zone 60

Semenoviceras mangyschlakensis 60

Semenoviceras pseudocoelonodosus 60

Semenoviceras uldigi 60

INDEX

27; 29; 31; 76

192; 195; 197; 200;

Semenovites michalskii 60

Semenovites michalskii Zone 60

Semicostatum Zone 180; 186; 200; 202

Senonian 83

Sentusidinium 224

Septaliphoria jordanica 220

Serbarinovella ringsteadiaeformis 26

Serbarinovella serbarinovi 26

serpulid 136

Serratum Zone 14; 23

Seychelles 134

Shair 37; 47; 48; 49; 51

shark 98

Shekat 143

Sherif 213; 214; 219; 224; 225; 230

Shetpe 60

Sheuringipollenites spp. 272

Shuqraia zuffardi 140

Shyrkala 61

Siberia 12

Sidi el Abed 147; 177; 178; 197; 203

Sidi Jabeur 167

Sidi Mohammed 130

Sidi Yahia ben Sefia 177

Siemiradzkia aurigera 168

Simbirsk 105

Simpheropol 97

Sinai 213; 214; 216; 217; 218; 219; 220; 221; 222; 225;

226; 227; 230; 232

Sinemurian 146; 154; 176; 180; 184; 186; 193; 197; 200;

202; 203; 238; 239; 243; 241; 242; 249; 250; 251; 252;

253; 254

Soaresirhynchia bouchardi 167

Sokolovi Zone 19; 25

Somalia 134; 226

Somalirhynchia 226

Somalirhyncliia africana 220

Somalirhynchia somalica 220

Sonniriia 2 18

Sosvaensis Zone 24

Souiga 185

Souiga-Melah 182

Souk-es-Scbt 259; 263

Sowerbyceras helios 223

Spain 224; 272; 277

Spathi 105

Spathian 39; 43; 44; 46; 67

Sphaeroceras 176

Sphaeroceras brongniarti 171

Sphenopteris pseudogermanica 272

Spiraloconulus cf. perconigi 227

Spirigerellina pygmaea 41

Spiroceras orbignyi 171; 176

Spitzbergen 12

sponge 136; 137

Source: MNHN, Paris

INDEX

293

spores 43; 220; 221

Stacheiles 43

Staufenia (=Ancolioceras) opalinoides 190

Steinekella cf. steinekei 227

Stephanoceras (Sk.) cf. skolex 176

Stephanoceras (Sk.) freycineti 176

Stephanoceras (Sk.) tlemceni 176

Stephanoceras (St.) densicostatum 176

Stephanoceras (St.) htunphriesiannm 176

Stephanolithion bigoti maximum 56

Stephanolithion hexum 56

Stepnoe 114

Stipa tenacissima 177

Stoliczkaia dispar Zone 105

Strenoceras gr. subfurcatum 177

Strenoceras subfurcatum 171

Strialoabieites richterii 43

Striatoabieites sp. 268

Strigoceras cf. paronai 176

Strigoceras truellei 177

stromatoporoid 131; 1232; 136; 137; 140; 143; 218; 219

Strongyloria 226

Stroudithyris fredericiromani 167

Stroudithyris pisolithica 167

Subditus Zone 22: 25

Surculosphaeridium 224

Susadinium scrofoides 53

Sutneria aff. subeumela 25

Sutneria cf. subeumela 19

Sutneria up. 192

Svalbard 43

Sweden 52

Syria 218; 227; 232

Systematophora 224

Syzran 12

Talgheml 181; 203

Talme Yale 220

Tamlelt 200

Tanzania 226

Taramelliceras cf. langi 223

Taranaki 124

Taral 275

Tarkhankut 97

Tasmanites 51

Tauride 123; 195

Tauromenia arethusa 180

Tauromeniceras 184; 190

Teisseyre-Tornquist Zone 75; 76; 79; 83; 88; 89: 90

Teloceras 176

Tendrara 180

Tenouchfi 134; 195

Tenuiplicalus Zone 168

Tenuiserratum Zone 23

Terebratula psilonoli 185

Terek 112; 114

Terquemuia cf. martini 226

Terquemula goldbergi 225

Terquemuia gublerae 225

Tertiary 124; 238

Tethys 106; 116; 120; 177; 200; 213; 214; 222; 223; 226;

227; 258

Textularia jurassica 54; 56

Thalassinoides 98; 100; 137; 138

Thambites planus 2 18; 222

Thaumatoporella parvovesiculifera 227

Tlioracosphaera sp. 65

Thuringia 262

Thuringian 272

Tiddas 257; 258: 259; 263; 267; 268; 272

Tigrai 131

Timidonella sp. 218; 227

Tinerhir 238

Tinjdad 237: 238; 249

Tiouli 157; 177

Tirrhisl 244

Tirrolites 44

Tisseddoura 157: 171; 176; 177; 205; 206

Tithonian 10; 12; 25: 26: 31; 59; 147; 204; 213; 221; 204;

205

Tizi n'Tesl 238

Tlemcen 145; 147; 149; 154; 157; 167: 201; 202; 204; 205

Tleta 171; 176; 203

Tmetoceras scissum 176

Toarcian 30; 51; 52; 53; 146; 147; 154; 157; 162; 163;

167; 171; 176; 177; 180; 184; 185; 190; 192; 195: 197;

201; 203; 204; 205; 213; 217; 218; 225; 227; 230: 231;

243; 244: 247; 249; 250; 251; 254

Tobin Range 43

Tolvericeras gr. sevogodense 19; 24

Tolvericeras sevogodense 19; 24

Tolypammina ex gr. gregaria 39

Tolypammina gregaria 45

Touissit-Bou Beker 167

Tounfite 237; 238; 244; 249; 252

Tranolithus pliacelosus 65; 66

Transcaucasus 123; 124; 128

Trans-Caucasus 112; 113

Transversarium Zone 220

Traras 146; 147; 160; 163; 200; 201; 203

Trautscholdia cordata 14

Triassic 35; 36: 38; 39; 43; 45; 46; 47; 48; 49; 51; 67; 68;

75: 80; 81: 82; 83; 89; 90; 98; 113; 120: 132; 180; 192;

197; 202; 203; 217; 230; 237; 238; 240; 251: 258; 260;

266

trigoniids 60

Trigonodua ( ?) roeperti 47

TrigonodUS hornschuchi 47

294

INDEX

Tristix lutkowskii 56

Trocholina palasteniensis 218

Tropidoceras 185: 200

Tropidoceras cdlliplocum 186

Tropidoceras cf. calliplocum 200; 201

Tropidoceras sp. 184; 195

Tuarkyr 94

Tunisia 106; 226

Turan 68

Turan Platform 95

Turanian Platform 106

Turkmenia 94

Turneri Zone 200

Turonian 30; 58: 60; 68; 81; 93; 95; 98; 100; 101; 102;

103; 104; 106; 107

Turrilites costatus 100

Ufimian 275

Ulianovsk 105

Ulyanovsk 12

Ulyanovsk-Saratov trough 10

Undory 12

Unzha River 12; 23

Urals 97: 106

Urbana 259

Ustyurt Plateau 44

Uvaesporites sp. 39

Valanginian 59

Variamussium 102

Venustostrobus 272

“Vermicera" rothpletzi 193

Veryhachium sp. 41

Virgataxioceras fallax 19; 24

Virgataxioceras sp. 19

Virgatites cf. sosia 21

Virgatites crassicostatus 26

Virgatites gerassimovi 21; 26

Virgatites larisae 25; 26

Virgatites pallasianus 21; 25; 26

Virgatites pusillus2\\ 25; 26

Virgatites rosanovi 26

Virgatites sosia 25; 26

Virgatites virgatus 21; 26; 26

Virgatus Zone 21; 26; 29

Visean 258; 260; 263; 266; 275

Volga 9; 10; 12; 24; 30

Volgian 12: 19; 21; 22: 25; 26; 27: 29; 30

Volgian basin 12: 23

“Volgian province" 10

Volgograd 113; 118

Voronezh 96

Wadi E Shatr 220

Walchia piniformis 275

Walchia spp. 272; 275

Walchiacean 277

Warszawa 79

Watznaueria 56

Watznaueria barnesae 58; 61

Watznaueria britannica 58

Watznaueria sp. 53

Watznaueria spp. 58

Weatleyites arkelli 25

Weatleyites aff. aestlecottensis 25

Weatleyites spathi 25

Wessex 30

Westphalian 258

Whiteinella 100

Whiteinella archeocretacea 102

Whiteinella archeocretacea Zone 101

Wola Morawicka 86

Wukro 143

Yorkshire 30; 218

Zaire 275

Zaraiskites michalskii 21; 25

Zaraiskites quenstedti 21; 25

Zaraiskites scythicus 21; 25

Zaraiskites tschernyschovi 21; 25

Zaraiskites zarajskensis 21; 25

Zechstein 80: 81

Zeilleria hierlazica 185

Zeilleria perforata 185

Zeilleria sarthacensis 197

Zeilleria sestii 180

Zeillerids 19

Zekkara 167

Zenaga 195

Zerqacythere subiehensis 225

Zigzag Zone 167

Zohar 214; 219; 220; 224; 225; 230; 231

Zohar-Kidod 220

Zoophycos 137; 171; 176; 177; 184; 195; 201; 204; 206

Zygodiscus diplogrammus 61

Zygodiscus erectus 58; 61

Zygodiscus spp. 58; 61

Zygodyscus 59

Remerciements aux rapporteurs / Acknowledgements to referees

La Redaction tient a remercier les experts exterieurs au Museum national d’Histoire naturelle dont les noms suivent, d'avojr

bien voulu contribuer. avec les rapporteurs do 1’Etablissemcnt, a revaluation des manuscrits (1995/1998) :

The Editorial Board acknowledges with thanks the following referees who, with Museum referees, have reviewed papers

submitted to the Memories du Museum (1995/1998):

Afzeuus B.

Stockholm

Suede

Ledouaran S.

Paris

France

Akam M.

Cambridge

Grande-Bretagne

Lemaitre R.

Washington

USA

Andersen N.

Copenhague

Danemark

Lovelock P. E. R

La Haye

Pays-Bas

AUGELLI 1

Milan

Italie

Lowrie J.

Zurich

Suisse

Baba K

Kumamoto

Japon

Machida Y.

Kochi

Japon

Bachmann C. H.

Halle-Wiltenberg

Allemagne

MacKinnon D.

Christchurch

Nouvelle-Zelande

Bally A. W.

Houston

USA

MacPherson E.

Barcelona

Espagne

Banks T.

Egham

Grande-Bretagne

Maddison D.

Tucson

USA

Baud A.

Lausanne

France

Manning R.

Washington

USA

Bellido A

Paimpont

France

Markle D.

Oregon

USA

Bergoren M.

Fiskebaekskil

Suede

Mas.aki S.

Hirosaki

Japon

Bernet-Rollande M.C.

Paris

France

Mascle A.

Rueil-Malmaison

France

Bernoulli D.

Zurich

Suisse

Masse P.

Paris

France

Bertotti G.

Amsterdam

Pays-Bas

Mauchline J.

Oban

Orande-Bretaene

Besse J.

Paris

France

McLaughlin P.

Washington

USA

BessereauG.

Rueil-Malmaison

France

McLennan D.

Toronto

Canada

BestM

Leiden

Pays-Bas

Merrett N

Londres

Grande-Bretagne

Bonavia F.

Paris

France

Messing C

Dania

USA

Bourseau J.P.

Villeurbanne

France

MeulenkampJ.

Ulrecht

Pays-Bas

Bruce J.

Helensvale

Australie

Morand S.

Perpignan

France

BruceN.

Copenhague

Danemark

Mugnier J.L

Grenoble

France

Brunton H

Londres

Grande-Bretagne

Nakamura I.

Kyoto

Japon

Carpenter J.

New York

USA

Naumann C.

Bonn

Allemagne

Cassagneau P.

Toulouse

France

Newman W. A.

San Diego

USA

CiiaceF A.

Washington

USA

Ng P.

Singapore

Singapour

Child C. A.

Washington

USA

Oliva R

Barcelone

Espagne

ClIERIX D.

Lausanne

Suisse

OroussetJ.

Paris

France

Clobert J.

Paris

France

Packer L.

York

Canada

Ci.oetingh S.

Amsterdam

Pays-Bas

Plateaux C.

Nancy

France

Cohen D.

Los Angeles

USA

Poccia D. L.

Amherst

USA

Cook P. L.

Victoria

Australie

Poore G.

Victoria

Australie

Cordey F,

Lyon

France

Proust J. N.

Lille

France

Cornudf.lla L.

Barcelone

Espagne

Raikova O.

Saint-Pdtersbourg

Russie

CUZIN-ROUDY J.

Vdletranche / Mer

France

Ravenne C.

Rueil-Malmaison

France

Darlu P

Paris

France

Rentz D. C. R.

Canberra

Australie

Danchin F,.

Paris

France

Richards W

Miami

USA

Davie P.

Brisbane

Australie

Roberts C.

Wellington

Nouvelle-Zelande

Dejean A.

Villetaneuse

France

Roure F

Rueil-Malmaison

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Deleporte P

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Salomon M

Marseille

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Dietrich C.

Champaign

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Sazonov Y.

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Amsterdam

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SCHWANDER M.

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Spiridonov V.

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Fleury A

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Stampfli G.

Lausanne

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Fodor L.

Budapest

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Stefa nescu M. 0.

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Fransen C.

Leiden

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Stewart A.

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TakedaM.

Tokyo

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GorinG.

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TanC. G. S.

Singapore

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Guglielmo L.

Messina

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Paris

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Gullan P.

Canberra

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Thorne B.

Maryland

USA

Gunzenhauser B.

Zurich

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Tribovillard N.

Paris

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Hancock P.

Bristol

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Harmelin J.G.

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Van Ameron H. W. J.

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Healy J.

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Heemstra P

Grahamstown

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Hodgson C.

Ashford

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Vickery Vernon R

Ste-Anne / Bellevue

Canada

HolthuisL. B

Leiden

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Horvath F

Budapest

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Bielefeld

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Frankfurt

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Waren A.

Stockholm

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Jordan P.

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Armidale

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Rabat A.

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Wenzel J.

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Washington

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Maryland

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Wilson M.

Cardiff

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ACHEV'fi DIMPIilMEH

EN DECEMBER 1998

SI R EES PRESSES

l’imprimerie E PAI1.LART

A ABBEVILLE

BIBL. DU

Imuseum]

k PARIS,

Date de distribution : 23 decembre 1998.

Depot legal: decembre 1998.

N" d'impression : 10511.

Source: MNHN, Paris

DERNIERS TITRES PARUS

RECENTLY PUBLISHED MEMOIRS

A partir de 1993 (Tome 155), les Memoires du Museum sont publies sans indication dc scrie.

From 1993 (Volume 155), the Memoires du Museum are published without serial titles.

Tome 178 : Alan G. BEU, 1998.— Indo-West Pacific Ranellidae, Bursidae and

Personidae (Mollusca: Gastropoda). A monograph of the New Caledonian

fauna and revisions of related taxa. Resultats des Campagnes MUSORSTOM.

Volume 19. 256 pp. (ISBN : 2-85653-517-8) 350 FF.

Tome 177 : Sylvie CRASQU1N-SOLEAU & Eric BARRIER (eds), 1998.— Peri-Tethys

Memoir 3: Stratigraphy and Evolution of Peri-Telhyan Platforms. 262 pp.

(ISBN : 2-85653-512-7) 260 FF.

Tome 176 : Alain CROSNIER (ed.), 1997. — Resultats des Campagnes MUSORSTOM.

Volume 18. 570 pp. (ISBN : 2-85653-511-9) 600 FF.

Tome 175 : Isabel PEREZ Farfante & Brian KENSLEY, 1997.— Penaeoid and Sergestoid

Shrimps and Prawns of the World: Keys and Diagnoses for the Families and

Genera. 233 pp. (ISBN : 2-85653-510-0) 350 FF.

Tome 174 : Bernard SERET (ed.), 1997.— Resultats des Campagnes MUSORSTOM.

Volume 17. 213 pp. (ISBN : 2-85653-500-3) 245,04 FF.

Tome 173 : Philippe GRANDCOLAS (ed.), 1997.— The Origin of Biodiversity in Insects:

Phylogenetic Tests of Evolutionary Scenarios. 356 pp. (ISBN: 2-85653-508-9)

490 FF.

Tome 172 : Alain CROSNIER & Philippe BOUCHET (eds), 1997. — Resultats des

Campagnes MUSORSTOM. Volume 16. 667 pp. (ISBN : 2-85653-506-2) 612,60

FF.

Tome 171 : Judith NAJT & Loic MATILE (eds), 1997. — Zoologia Neocaledonica,

Volume 4. 400 pp. (ISBN : 2-85653-505-04) 450 FF.

Tome 170 : Peter A. ZIEGLER & Frank HORVATH (eds), 1996. — Peri-Tethys Memoir 2:

Structure and Prospects of Alpine Basins and Forelands. 552 pp. + atlas.

(ISBN : 2-85653-507-0) 450 FF.

Tome 169 : Jean-Jacques GEOFFROY, Jean-Paul MAURIES & Monique NGUYEN DUY-

JACQUEMIN (eds), 1996. —Acta Myriapodologica. 683 pp. (ISBN : 2-85653-

502-X) 550 FF.

Informations sur les Publications Scientifiques du Museum national d’Histoire naturelle :

Informations about the Scientific Publications of the Museum national d'Histoire naturelle:

Internet http://www.nmhn.fr/

Prix TTC, frais de port en sus.

Prices in French Francs, postage not included.

2 3 DEC. 1993

Source: MNHN, Paris

The Peri-Tethys Programme, started in 1993, examines the influence of the Tethyan

evolution on the bordering cratons since the birth of the Tethys Sea (through the break-up of the

Pangea), its life (by the extension and formation of oceanic seaways) and finally its death (by col¬

lision between the main bordering plates which led to inversion within the epicratonic

basins).

The Peri-Tethys Memoir 4, as the previous one (Peri-Tethys Memoir 3), is subdivided in

two parts which correspond to the two great geographic domains involved in the Program: the

Northern Platform and the Southern Platform (5 papers on each). It is mainly devoted to the

Mesozoic (one paper on the Permian and one on the Cainozoic). In the first part, the first paper

concerns the Jurassic ammonites and the organic matter of the Volga Basin, the second and the third

papers are devoted to the Mesozoic evolution of, respectively, the Mangyshlak (Western

Kazahkstan) and the Holy Cross Mountains (Poland). The fourth presents the main mid-Cretaceous

events in Eastern Europe. The last paper alludes to the Cainozoic modelling of the Fore-Caucasus

Basin. In the second part, the four first papers develop Jurassic stratigraphic analysis of, successi¬

vely, Northern Ethiopia, Western Algeria, Levant and Morocco. Finally, the last paper approaches

the Permian phyto-biostratigraphy of the Central Morocco.

Sylvie Crasquin-Soleau and Eric Barrier (CNRS - Universite Pierre et Marie Curie, Paris)

coordinated this volume which follows the International Peri-Tethys Meeting held in Amsterdam

(June 1996).

PUBLICATIONS

SCIENTIF1QUES

DU MUSEUM

57. RUE CUVIER

75005 PARIS

ISBN 2-85653-518-4

ISSN 1243-4442

300 FF TTC

Source. MNHN. Paris