Upper Permian and Triassic of the Precaspian Depression: stratigraphy and palaeogeography

22 Pages·1999·6.3 MB·English

by  Sylvie Crasquin-Soleau

Upper Permian and Triassic of the Precaspian
Dépréssion: stratigraphy and palaeogeography
Dmitri A. KUKHTINOV
Palaeontology Department, Faculty of Geology, University of Saratov,
83 Astrakhanian St., Saratov 410071 (Russia)
ccvg @ mail.saratov.ru
Sylvie CRASQUIN-SOLEAU
CNRS, UPRESA 7073, Université Pierre et Marie Curie, Département de Géologie sédimentaire,
T. 15-25, E. 4, case 104, F-75252 Paris cedex 05 (France)
[email protected]
Kukhtinov D. A. & Crasquin-Soleau S. 1999. — Upper Permian and Triassic of the
Precaspian Dépréssion: stratigraphy and palaeogeography, in Crasquin-Soleau S. &
De Wever P. (eds), Peri-Telhys: stratigraphie corrélations 3, Geodiversitas 21 (3) : 325-
346.
ABSTRACT
The stratigraphie scrie of the Precaspian Dépréssion during the Upper
Permian and the Triassic is analysed. Data from seismic sections and from
numerous boreholes are used. The lithological composition and the palaeon-
tological content are cleared for ail rhe time inrerval. Three palaeogeographi-
KEYWORDS
Precaspian Depre.s.sion, cal maps are drawing for che Kazanian, the Lower Triassic and the Mîddle
Upper Permian, Triassic. The évolution of palaeoenvironments is restored in relation to the
T riassic,
tectonic events and the fluctuations of the Boréal Sea and the Palaeo-Tethys
stratigraphy,
palaeogeography. Océan.
RÉSUMÉ
Le Permian supérieur et le Trias de la Dépression Précaspienne : stratigraphie et
paléogéogaphie.
La série stratigraphique de la Dépression Précaspienne est analysée pour le
Permien supérieur et le Trias. Le.s donnée.s de profils sismiques et de nom¬
breux forages sont utilisées. La composition Üihologiquc et le contenu
paléonrologique sont précisés pour l’intervalle de temps considéré. Trois
MOTS CLÉS
Dépression Précaspienne, cartes paléogéographiques sont établies pour le Kazanicn, le Trias inférieur et
Permien supérieur, le Tria.s moyen. L’évolution de.s paléoenvironnements est établie en relation
Trias,
avec les événements tectoniques et les fluctuations de la mer Boréale et de
stratigraphie,
paléogéographie. l’océan Paléo-Téthysien.
GEODIVERSITAS • 1999 • 21 (3) 325
Kukhtinov D. A. & Crasquin-Soleau S.
INTRODUCnON sis Palanc. D. cf. trita Paiani, D. cf. pyriformis
Kashevarova). The bivalve Palaeomutiia cf. stego-
The Uppcr Permian and the Triassic of the cephalum Nechaev, as well as miospores and
Precaspian Dépréssion and adjacent areas are conchostraceans> permit the corrélations with the
represented by marine and continental deposits. synchronous deposits of Aktjubian Pre-Uralian
The compicx original rclaiionships becween these zone.
deposits hâve bcen modified by ihe sait tectono-
genesis. The sali dômes are widely distribuied In ihc central part of the Dépression, the red
(Fig. 1 ) and dic uppcr part is oftcii eroded. The argilites and sandstones with inclusions of anhy-
most complété sections are in ihe dépréssions dritc drilled in rhe Aralsor well (6630-6806 m)
between the dômes. We présent hcre new data are related co the Ufimian (Fig. 6). The thickest
which complote the previous work (Kukhtinov Ufimian deposits (more rhan 581 m) were
1976, 1984) on stratigraphy and deposirional drilled in l.injovka S well (locality 43 on Fig. 7)
conditions. on the northern edge. They arc composed of
grey and red terrigenous, carbonated and sulfate-
halogcnous rocks with non marine ostracods
STRATIGRAPHY (Table 1) (D(irwinubz nhandii Mandelstam, D. acervalis
Mandelstam, D. aff. pnrplH’novae Belousova,
The Upper Permian (Pd D. sifhaclhns Zhernakova), bivalves (Palaeo-
The Upper Permian deposits are irregularly stu- mutc4a ex gr. ovataeformh Gussev, P. cf. pseii-
died. They were drllled during the oil and ga.s doumbanain Gussev, Anthraconaia rhomboïdes
prospecting, mainly on rhe borders of the Netschajev), conchostraceans, fishes and charo-
Dépréssion (Figs 2-5). (n the ceMural part oi ihe phyres.
basin, in the Aralsor 1 horchole (localîty 2 on
Figs 6, 7)t the Uppcr Permian succession is rcco- In northern and western edges of rhe I3epre.ssion,
gnized benveen 6806 and 5492 ni., The base of chc Ufimian is defined between ihe Kungurian
the Uppcr Permian is nor reached. The most anhydrites and ihc Kazanian clays and carbo-
complète sequence is located on the easiern bor¬ iiaiesî 30 to 70 m of red and grey sulphate-ierri-
der of the Dépréssion where ail substages are cha- genous, halogenic and rarely carbonates rocks are
racteriscd by lheit palaeontological content recognised. In rhe south-western part, the
(cxamplc Lugov boreholc. No. 45 on Figs 6, 7). Ufimian terrigenous deposits (63 lo 1242 m) are
disringuished by spores and polleas. The .spore
The UfiTnmii (Put) and pollen .spccira shows prédominance oi snia-
In the eastern part of the Dépréssion, two terri- tïti (up Uï 52%) and Viuaiina (27 to 37%).
genous units were rccognised (Fig. 6). The lower These deposits arc includcd in the Volozhkov-
one (Piui) is grey (200-300 m) and has not clear skaya suite (wi'ihout subdivision) from Ufimian-
bovmdarv wicK ihc underlying Kiingurian. Ir is Kazanlan (Pronicheva & Savinova 1982).
composed of finc-grained sandstoncs, claystones
and aleurolites — aleurolires is more or Icss équi¬ The Kitzonuw Stage (Pjkz)
valent ro silrstone in Riissian üteraiure. The It is represenred by two sut>stagcs (lower and
upper unir (Piu:) i.s red (200-300 m) and is upper) in moM of îlie Preaispian [Répression and
mainly represented by sandstones, lu both units, its northern and western adjacent areas.
anhydrites and sait lenscs arc someiimcs inter- Lower Kazanian substage (p2kz,), The
layered and typical o.stracod.s of the Darwimtla Kalmovskaya suite is composed of clays, dolo¬
angusUi zone from the Russian platform Ufimian mites, liincstones, rarely sandstones with marine
(see for example Molotovskaya 1997) are a-cove- macro- and microfauna' brachiopods \Camrï-
r e d {D a r tif i n nia ht b imo vue K a s h c v a r o v a, nclia caticrlni Verneuil, Beecheria netsehaevi
D. angusta Mandelstam, D. lanzetiforrnis Grigorieva, Cleiothyridina reussiana (Keiserling),
Kashevarova, D. fainaehcXoxxsowz, D. burajevoen- C. pectinifera (Sowerby)], bivalves Pseudomonotis
326 GEODIVERSITAS • 1999 • 21 (3)
Upper Permian and Triassic of the Precaspian Dépréssion
45E 55”E
Fig. 1. — Tedonic charl of lhe Precaspian Dépréssion, Tectnnic fealures 1 Akhtubirisk-Palassowski megamound;
2, D2hanybeckoe rise; 3. Altatinsk-Nikolskiy mouncJ: 4. Karachaganak-Koblandinskay upltfl; 5, Temirskiy dôme. 6. Kzyloshafskiy
dôme: 7. Zharkamyssiy dôme: 8. Oosaorskiy iroucjh 9 Biikzhalskiy dôme; 10. South Emba uptift: 11. Gunev dôme, 12, Karaton-
Tengiz uplîH; 13. ZhayksKiy dôme; 14, North-Caspian dôme; 15, Akkolskiy dôme; 16, Mynlobinskay uplift 17, Kobyakcvskoe uplift;
18, Octyabrskoe uplitt; 19. Azgirskoe uplift; 20, Astrakan dôme: 21, Suvodskaya uplift: 22. ÛlKhovskay dépréssion; 23. Archedino-
Don mound: 24. Zhirnovsko-Umetuvskiy mound, 25, AntipovsKo-Shefbakovskîy mound 26, Tersinskaya dépréssion: 27. Zolotovsko-
Karnenskaya uplift: 28, KaramyshsKaya uplift. 29, Eishano-Sergievskiy mound; 30, Stepnovskiy mound: 31, Voskeresenskaya
dépréssion; 32. Saratov displacements. 33. Kazanlinskiy monud. 34. Pugachevskiy dôme; 35, Marievskaya upüft, 36, Balakovskaya
uplift; 37, Klinisovskay uplitt; 38. Kamellk-Chaganskiy mound, 39. Zemiyanskiy mound: 40. Syrtovskiy mound,
elengatula Netschujev, Parallelodon kingi Verneuil, Kotschetkova, Cavelliniû et. univa Kotschetkova,
P. cf. strÛHUs (Schlocbeim), Bdmondia elongata C. ex gr. edmistonae (Harris & Lalicker)]. The
House, BakevcUia (Bakevellia) cerataphaga ihickness varies tram 0 to 168 m.
(Schlorheim)]i bryozoa \^DyscYitel!a hnrustaia In elle soiuh-wcstcrn part of the Dépréssion, the
Morozova]> foraminifcras \Palcieonuhecïdana upper Volozhkovskaya suite is composed of red
uniserialfs Reitlinger, P fîtixa Reiilingcr, and grcy terrigenous rocks. In the south, the
Geinit7>Piii pu^illa Grov-dilova. G. spundeti Zhambay 22 \yell (nored 3 on Fig. 7) shows
Tscherdyn/ev, G. cf. postcarbonicti Spandcl, untler the Triassic, terrigenous rocks with bra-
Nodosarina ehibugae Tschcrdynzcv, TV. netscbevi chiopods, pelecypods, ostracods {Danainula sp.,
Tscherdynzcv, Spandelli)ia ex gr. cordiformis Mùorea d. fadlis Schneider) of lower Kazanian
Gerce], ostracods [Healdia subtriangula substage. In ihc east of the Precaspian Depres-
Kotschetkova, U. simplex Roimdy, Healdianelbi sion, the séries (700 m), composed oF regularly
vulgata Kotschetkova, H. parallela Knight, //. ex interlaid sandscones, aleurolites, argilites and
gr. osagensis Kellett, H. ex gr. panda limestones with locally sait lenses, is synchronous
GEODIVERSITAS • 1999 • 21 (3) 327
Kukhtinov D. A. & Crasquin-Soleau S.
SUITE
1 STAGE HORIZON SERIE
West Centre and North-West East
Kusankudukian Tsks
T3 iü
Koktinskaya
Aralsorskaya
(cid:9632) Chobdian Tach Barmantsakskaya Chobd*nçkava-T;kfi|
(cid:9632) J2ak Sarpinskaya Akmamykskaya
T2 Masfôksaiskian Tams MasleksaisKava
Inderlan Tzin Akmaiskaya Inderiskava Inderskava lasshii-skaya
Anisian Eltonian Taei Taak Eltonskaya Btonskaya k’MvLcuc. Tjiw
Akzharsajskaya
Otenelyan Baskuntchakian Tibs Aktubinskaya Zhulidovskaya T^kz
T1
Kokzhidinskaya-Tivr
Induan Ershovian Tier Prikaspinjskaya Bugrinskaya Ershovskaya Sorkoiskaya-T’sk
Viatkian P£vt Viatkian
Severodvlnian P?5d Batyrmolinskaya Sererodvinian Sererodvinian
Urzhmian P2ut Urzhumian
mgi P2kr£ Upper Kazanian upper Kazanian
P2
tower Kazanian Pakzi Kalinovskaya Kalinovskaya
Volozhkovskaya
Ufimlari upper Uflmian P2u2 Sheshmian Sheshnnian-P2sh
P2u lower Ufimian P2u1 Solikamian Soljkamian-P2si
Table 1. — Upper Permian and Triassic stratigraphie subdivisions of the Precaspian Dépréssion.
with the Knlinovslayn suite. Tlie organic remains var Bclousova, D. innocurovi Bclousova, D. ncco-
are crinoid.s, oscrucods (Sinmuella cf. ignoia rfiüdiita Starojilova, D, inornalina Bclousova,
Spizharskyi, Darwinula varsaviffievae Belousova, D. ulexandripiae Bclousova, Suchonella helebeica
D. irinae Bclousova, D. i^elica Starojilova. Bclousova, 5. onega Bclousova, 5. snpttLi Belou-
D. accomodatü StarojUova, D, ex gr. tichivinskaje sova, Darwinulüides stntjakensh Sharapova,
Bclousova, Sut'honelU onegi'i Bclousova, S. belehei- D. edniistonae Bclousova. D. tnnnguUt Bclousova,
ca Bclousova, S. sacmaremis Starojilova, SinusKcIltt ignota Spizharskyi], spores and pollen
Darwimiloide^ ednnstonae Bclousova, D. sentja- which arc charactcxistic of the whole Kazanian
kensis Sharapova, D. iriangida Bclousova), non stage or of its upper substage iu the most areas of
marine pelecypods, miospores. Fhey allow the the Russian platlorm.
comparison with the Akjubian (low'cr Kazaniaii In tlie centrai part of the Dépression, the upper
or Kazanian) ot Pre-Ural and Russian platform. Kazanian substage is composed of red aleurolites
Upper Kazanian substage (P kz). The upper and argilites with marine and non-marine ostra-
2 2
Kazanian substage is evcrtwhere represented by cüds [Healdia sp., IJealdianelh vulgnta
terrigenous rocks. To the east of the Dépréssion, Kotschetkova, Hmldiandln sp.. Monôcemtinci aff.
the sériés is composed of sandstones with conglo- exith (Schneider), Schnehierta ex gr. kotschetkovae
merate at the boicom and argilitc interbedded Starojilova, Darwinula sp., Snchondta sacnnnensis
(mainly in the upper part). In this séries (400- Starojilova, 5. Hehwinskaja (Belousova), Ptaddea
500 m), rhey arc quite often non-marine bivalves sp., Tomielta sp.|. 'fhc thickness rcaches 345 m.
[Palaeomutela ex gr. krotûvi Nechaev, P. ex gr. On the northern Dépréssion border, on che
doratioformis Gussev, P, ef. iimhonata (Fischer). Kidinovskaya suite, the red atgiliies with anhy-
P. cf. vjatkensis Gussev, Palaeanodonta rhomboi- drite and sait inclusions, could be palaeontologî-
dea (Nechaev)], ostracods [Darwimda varsanofie- cally correlatcd with che upper Kazanian deposits
328 GEODIVERSITAS • 1999 • 21 (3)
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Plar, Artinskian; Plk, Kungurian; P2kz. Kazanian; T Triasslc; Tl, Early Tnassic: J. Jurassic; K, Cretaceous; K1, Early Cretaceous; K2. Laie Cretaceous; Pal, Palaeogene; N2, laie é
p
Neogene; III. 112.113, the three main dîscontinuilies; F. major fault. ré
ssio
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Kukhtinov D. A. & Crasquin-Soleau S.
of the Orenburg Pre-Ural adjacent area. {Suchonellina inornata Spizharskyi, S. panillela
In other areas, chère are no data reliable to the Spizharskyi, Suchonella stelnuirhom Spizharskyi,
upper Kazanian substage. Volgtinella magma Spizharskyi) characteristic of
the North Dvinian horizon and which allow the
The Tatarlan Stage (Pj^) corrélations with Southern Urals (Molostovskaya
Lower Tatarian substage (Pat,). In the eavStern 1907).
part of the Dépréssion, the lower Tatarian is In the central parr, in the Aralsor well (58^5-
represenred by red clays (600-800 m). The osera- 5492 m) (locality 2 on Figs 6, 7), the upper
cods are non-marine [Darwinula elongata Tatarian présents red and grcy sandsrones, aleu-
Lunjak, D teodorovichi Belousova, D. tichonovi- rolites, argillites and clay maris svith ostracods of
chi Belousova, D. (ragtliformh Kashevarova, uhc Viatkian horizon (Darwinutoides tataricus
D. elegantelln Belousova, D. perlonga Sharapova, Posncr, D. svijnzhicus Sharapova).
D. torensis Kotschetkova, Sucbouella nasalis
Sharapova, Daywinuloides dohrinkaemis Kashe¬ As a wholc, the Upper Permian has not been stu-
varova). Sortie non marine pciccypods wcrc died in full. h is mainly represented by red cerri-
found (Palaeanadopttit mvalis Nechaev, P. ver- genous deposits. which are trnditionally regarded
neuili (Amaltisky), P, cf. longissima Nechaev, as continental. In general in Ru.s.sia, ihc lower
P fischeri Amalfisky, Pnlneirmiittda vjatkemis Kazanian is marine. On the lOepression periphe-
Gussev, /? plana Amaltisky, Authraemaia sp., ry. there are red interbeds with marine fauna.
Microdontella sp.). Spores and pollens confirtn The maximum thickness of the Upper Permian
the stratigraphie attribution. is located on eastern and Southern horder.s ol the
In the central part, the Arasol well (localicy 2, Dépression.
Figs 6, 7) présents, in ihe inierval 6045-5875 ni,
red-brovvn aleurolires and argiliies with the non- Lowhr TlUÂSSic (T,)
marine ostracods {^Darwinidoides djurtjulensis The Lower Triassic deposits of the Precaspian
Palant, Volganellu sp.) atttibuted to the lower Dépression and its adjacent areas overlay with
Tatarian. unconformity varions Permian levels. In the cen¬
In the north-western pan of the Dépression, the tral part ot fhe Dépréssion, the contact between
sériés is forined of red clays> alcurolites, sand- Permian and Triassic is not known.
stones with anhydrite inclusions. It contains cha- The Lower Triassic corresponds hcrc to chc inter¬
rophytes froin ihc Taiatian and ostracods from national subdivisions (Induan and Olcneldan). At
the lower Tatarian [Darwinula fragiliformis the régional scale (Anonymous 1982), it is referred
Kashevarova, Z), elongaia Liinjak, Snchnnella Lo the Frshovian and Baskunchakian horizons
nasalis Sharapova! and from the upper Tatarian (Table I).
(Suchonellina inornata Spizharskyi, S. parallela
Spizharskyi, Suihonctla stebnachovi Spi/har.slc)'i). The Ershovian (T^^J
The thickness varies from 0 to 2030 m. Ourside It is accuraiely defined. It consists of continental
of the Dépression, siinilar deposits were obser- red terrigenous deposits laleurolites, argilites and
ved, with both substage ostracod assemblages, rare sandstones; Figs 8. 9) with ostracods
and hâve a thickness of 0 to 300 m. \Darwiniilla ovalis Glebovskaya. D. quadrata
In the sou ch-western part, the red terrigenous Mischina, D. dubia Starojilova. D. regia
deposits (about 1200 m) are rclaied to the Mischtna, D. ^n?r/y Mischina, D. pseudoinomata
Tatarian Batyrmolinskaya suite by ihc presence Belousova. D. postparallda Mischina, Gcrdalia
of spores and pollens (complex j) as well as the weîliigensis Belou.sova, Snchonella postt)’pica
ostracod Sttcbonellirui. Stafojilova. S. circula Starojilova, S, rykovi
Upper Tatarian substage (^ * )* clearly vStarojilovâ (Darwinula quadrata-D. dubia zone)J,
2 2
defined on the inner border of the ea-Stern part of conchostracans {Vertex/a tauriconis Lutkevich,
the Dépression, where it is represented by sand- Cyclôtungtézites guffa Lurkcvich], charophytes
stones and clays (up to 600 m) with ostracods [Vladirniriella globosa {Sâidâkovsky), V wetlugen-
330 GEODIVERSITAS • 1999 • 21 (3)
SW/NW SE/N S/NW SE/NNE SSW/NE
Stepnov Lubimov Erusian Karpen Vladimirov Timofeev
101 33 20 19 15 5 8 3 2 4 20 519 7 19 14 2 1

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Fig. 3. — Geological-geophysical cross section GG 07 (location on Fig. 7). North-western margin-central part of Precaspian Dépréssion. Legend: see Fig. 2
Kukhtinov D. A. & Crasquin-Soleau S.
i-zV SaidakovskyK spores and pollen. The Bogdoninskaya suite. 24 to 100 m of
Vertexia îatiricornis are aiso kjiown in dcposits of variegated clays following by grcy clays with
middle parr of the Vetluzlikaya séries of the limestoues interbedded.
Moscow syncline, tlie Kopanskaya suite of the Ccpbalopods: TiroUtes cassietnus (Quenstedt),
Volgo-Ural anticline, in the niiddlc part of the Dorikranites bogdounus (Buch.), D. acutus
Korenevskaya suite of the Prypiat trough ot the (Mojsisovich).
Russian platform and in lower variegated sand- Pelecypods: Mytilui tuarkyrensis Kiparisova,
stone in Germany (Nordhausen and Bernburg Myijl'ma dakilamae (Verneuil), Unionites fassaen-
suites). sis (Wis.smann), U. canalerisis (Catullo).
Brachiopods: Lingula.
In the eascern part of the Dépréssion (Blacktykol letrapods: Parotosuchus bogdoamis S. Woodward.
well; lotaliry 46 on Figs H, 10)j the Fishes; Cemtodus midticriUatus mxdticrhtatus
Blacktykolskaya, Sorkolskaya and Kokzhidin- Minich, Gnathorïza triassica haskuntchûkensis
skaya suites are clearly ideniified. The Minich, G. bogdemis Minich.
Blacktykolskaya suite (maximum ut tliickness Ostracods; TriassinelLi chramovi Schneider,
90 m) overlics with unconlormity the Permian. Clinùiypri> cognata Siarojilova, C couferta
It begins by a conglomerare Icvel following by Starojilova, C. oleneca Kukhtinov, Darwinula
sandstoncs and clays. To the cast, rhis suite is mîundnta Luber, D. parm Schneider, D, nota
absent and the Sorkolskaya suite lies on the Schneider, D. acuta Mischina, Gerdalia dactyla
Permian (Kenkiyak well; loeality 44 on Figs 8, Bclousova, Uogdoella delicata (Starojilova),
10) with a maximum tliickness oi 87 m. The B. antiqua Starujilora.
Kokzhidinskaya suite Table 1; up to Charophyces: various Porochara and lot the first
140 m) is composed of clay sandsrones with clay rime Auerbachichara.
interbeds. Conodonis, conchostracans, plants, spores and
In others areas, the Ershovian horizon is undiffe- pollen.
rentiated, with red sandy clay deposits. The The Enotajevskaya suite. 57 m of grey and
thickne.ss varies front 0 to 340 m. variegated sand-clays with charophytes
{Porochara Vladimirella) and ostracods domi-
The Baskunchakuni ( nared by Gerdalia {Gerdalia dactyla zone).
This horizon combines the marine deposits of
the Baskunchakian suite (Table 1) and its conti¬ Laterally chc Alchtubinskaya and Bogdiiiskaya
nental analogue. In Bolshoi Bogdo Mountain suites (Table 1) arc gcncrally combined in a clay
(the only outaop in the area) four suites (West unit ol 400 m rhick. On the eastem border, the
in Table 1) arc distinguished. Ak/arsajskaya suite ovciiays it in contormity and
The Busulukskaya suite. 96 ni of red and grey is rq^resented by red sand clays up to 150 ni. On
sandstones without organic rcmains. the üuter edges, to ihe rtorth, the Krasnokut-
The Akhtubinskaya suite. 64 m ot red aleiiroli- skaya suite consisted of sandsrones following by
te clays with numeious lossUs. cUys (273 m) and to the west the Berezovskaya
Charophytes: Porochara triassicit (Saidakovsky). and Lipovskayâ (or only Lipovskaya) suites (0-
Ostracods: Clinocypris trias^iai (Schneider), 256 m) arc transgressive and overlay the Permian
C. elongata (Schneider), Darwinula oblonga or Upper Carbonilerous. Ail thèse suites arc
Schneider, Gerdalui longa Beluiisova. referred to the Baskunchakian horizon.
Co n c h os t ra ce a n s : Cyclotu nguzites gutta The corrélations could be well-cstablished bet-
(Ltitkevich), Lioesthena Novojilov. ween Ba.skunchakian horizon and synchronous
Ichtyofauna; Csnathorhiza trlassicii haskuntschU’ deposits of the Russian Platform by fishes
kensis h'linich, C7. bogdoemis Minich, G. otschevî (Minikh & Minikh 1997). l'he fauna of
Minich, CenUodui rnnUicrislatus feodorensis Payoîostichus is found also in the sections of
Minich (sec also Minikli & Minlkli 1997). Volgo-Uralian anticline, Preuralian and Pripyat
Bivalves: Bakewellia lipatovae Kiparisova. throughs, Moscow and Mezensk synclines and in
332 GEODIVERSITAS • 1999 • 21 (3)
G
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D
IV
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IT
A
S

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1
9
9
9

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21 (3)
fp
p
er P
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ria
Fig. 4. — Geological-geophysical cross section GG 051 (location on Fig. 7). South-eastern part of Precaspian Dépréssion. Legend: see Fig. 2. ssic
o
f th
e
P
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ian
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é
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Kukhtinov D. A. & Crasquin-Soleau S.
the variegared sandstone of German basin. The lower suite, there are Gloridnella inderica
ammonites Dorikranitcs and TiroHtes allow to Schleifer, Renngarte7iella distinvia Starojilova,
correlate wirh the upper Olenekian ofRussia and Cytherissinella orispa Schleifer from the
with the Campile beds o( Alpine Triassic and the Glorianellcl inderica zone. Tn the upper .suite, the
Spathian Tirolites zone (Shevyrev 1990). tollowing species Irum the Pulvielht aralsofica
zone occur: Pulinelh aralsoriça Schleifer, P obola
Middlf Trtassic (T^) Schleifer, P. lubimovae Schleifer, P, directa
The Akmajskaya and the lower Aralsordkaya Starojilova, P marimie Starojilova, Speluncelia
sériés are artributed to the Middle Triassic auerbachi Schleifer, .S. spiriosa Schneider,
(Table l). Inderelln usimica Schleifer, Aralsorella uralica
Scldcifer. Moreover, there are bivalves and ga.stro-
The Akmajskaya séries pods Lhiionites fassaensis (Wissmann), (/. rriuens-
It is distribured in most part of the Precaspian teri (Wissmann), Cryptunerita elliptica Kittl,
Dépréssion. The basal boundary is marked by Actaeonina mediuculcis Ilohensiein, vcftebrares
the change of the Baskunchakian clay in the Mtistodmnaurîis torims Konzhukuva, Plapoicutam
sandstones of the Middle Triassic. Two suites are caspiense Shishkin, which allow the corrélation
recogniscd: the Eltonskaya and the Inderskaya with the lower Kcuper of the Central Europe
(Fig. 9). (Shishkin Ôc Ochev 1992).
The Eltonskaya suite (T2ei). le begins with
sandstones follovved by clays and limestones. fhe To the south-w'estern part of the Dépréssion, the
total thickness varies from 100 to 400 m. .\kmajskaya sériés présents mainly clays and the
The lowci part, terrigenous, contains the transi- thickness groAvs up to 1200 m. To the west, on
tional complex with mainly l.owcr Triassic .spc- the borders, ic changes in variegated terrigenous
cies and lew' Middle Triassic species {Dartvinula deposits of chc Morovovskaya suite (275 m) with
recondita Schleifer, D, Ltuta Schleifer, D. acmayi- charophyres, ostracods and in some layers
ca Schleifer, D. postinornata Schleifer, Suchonella Cytherocopina of Inderskaya suite. To the cast,
flexuosa Starojilova Irom ihe Dutwwula lanta the Akmajskaya suite is complerely replaced by
zone). the variegated .sand-clay Ta-shtiskaya suite (l'zts;
The upper part, clay and carbonates, is typical 230 m; Fig. 3) whh charactcrisdc non-marine
from the Middle Triassic (iMtkevichinella involn- ostracods and charophyres. Outside of the
ta Schneider, L bmttanae Schneider, L. minora Depression to the north and to the east, the
Starojilova, Pulvivlla iwalis Schneider, Trkminella Middle Tna.ssic is mlssing.
^ubkini Schleifer, (2hrocypris vasilievi Schleifer,
forming ihc LutkevichineUa brunanae zone). The Arahnrskaya p.p.
The Eltonskaya suite contains tetrapods as This sériés contains grey to variegated terrige¬
Plagioseutum ochevi Shishkin, Capitosauridae, nous and calcareous deposits from Middle and
referring to L'ryosUi’htft w^hich is wcll correlated Upper Triassic (Figs 1 T 12). The Lower Jurassic
with fauna of Central Europe (Shishkin & Re.sobinskaya suite overlays it with important
Ochev 1992). uncorformity (Shclcchova et al. 1989). The
The Inderskaya suite (Tjj^). It présents clays Aralsorian is subdivided in six suites:
and carbonates on a thickness ot 100 to 250 m. Masteksajskaya, Almamyskaya, Chodinskaya (the
three from rhe Middle Triassic), Koktinskaya,
Both suites (Eltonskaya and Inderskaya) are cha- Shalkarskaya and Kusankudukaya (the three
racterised by a single Middle Triassic Darwinu- from the Llpper'rfia.ssic).
locopida ostracods assemblage (DarwinuLt obesa The Masteksajskaya suite (T2„,j). h is compo-
Schleifer, D. kiptschakensis SchleOer, D. lenta sed of grey to Black clays, aleurolites, rarely sand¬
Schleifer, D. lanta Schleifer, D. recondita stones and limestones (210 m). Il overlies the
Schleifer, D. acmayica Schleifer) but by diHerent Akmajskian sériés {Pulviella araLoria zone). Its
Cytherocopina ostracod assemblages. In the red analogous deposits extend to the east through
334 GEODIVERSITAS • 1999 • 21 (3)