Silantiev V.V.

Zharinova V.V.

Kazan Federal University Digital Repository

135Another situation is observed in the Vaga fluvial system. We identified the well-expressed grayish varved clays within the valleys of Vaga and its tributaries Kuloi and Kokshen’ga. The maximum (10 m) thickness of varved clays was observed in the outcrop near the Kuloi-Vaga confluence; thickness of sand and silt layers varies significantly, from several mm to several tens of cm, that means the unstable hydrodynamic regime, with alteration of lacustrine and fluvial sedimentary environment. At the top of the lacustrine unit there are water-escape structures characteristic for the proglacial lake deposits. Upstream the thickness of varved clay layer decreases and then recedes completely. The limit of varved clay deposits goes form SW to NE from Vaga to Kokshen’ga rivers. Therefore, we can identify one episode of proglacial lake formation in the Late Pleistocene within the Severnaya Dvina catchment area. Two separate lake systems formed during the LGM (~ca 20 kyr BP): the Severnaya Dvina rather small, short-lived and shallow lake occupying only the middle reaches of SD river valley, and large, deep, long-living and braided Vaga lake occupying the valleys of Vaga and its tributaries Kuloi and Kokshen’ga. Such a difference in lake configuration and history could be explained by morphological features of river valleys, runoff volume and position of glacioisostatic forebulge crossing these river systems. The absolute height of water level could reach 80 m a.s.l. The studies of LGM glacial boundary are supported by Russian Science Foundation (RSF), project 17-17-01289,  the  sedimentary and geochronological data was obtained due  to financial  support of RFBR grant 17-05-00706, following the plan of the scientific research of the Geological Institute of RAS № 0135-2018-0037.REFERENCES1. Atlasov R.R. Relief peculiarities of terminal zone of Valdai glaciation on Onega-Vaga waterdivide and in Vaga valley. In: Kraevye obrazovania materikovych oledeneniy (Terminal formation of continental glacia-tions). Kiev. – Naukova Dumka. – 1978. – P. 30–38 (in Russian).2. Demidov I.N. The Stratigraphy of the Upper Pleistocene of southern part of the White Sea basin // Re-gional Geology and Metallogeny. – 2007. – P. 179–190. [In Russian].3. Fredin O. Distribution of ice marginal moraines in NW Russia // Journal of Maps. – 2012. – P. 236–241.4. Krasnov  I.I. Quaternary deposits  and geomorphology of  the Kama-Pechora-Vychegda  interfluve  and adjacent areas. Materialy po geomorfologii Urala. – 1948. – Issue 1. – P. 47–88. [In Russian].5. Kvasov D.D. Late Pleistocene history of large lakes and inner seas of Eastern Europe. Leningrad. – Nauka. – 1975. – P. 278. [In Russian].6. Larsen E. Subglacial sediment, proglacial lake-level and topographic controls on ice extent and lobe geometries during the Last Glacial Maximum in NW Russia // Quaternary Science Reviews. – 2013. – 92. – P. 369–387. 7. Lavrov A.S. Neopleistocene of the North-East of the Russian plain\. Moscow. Aerogeologiya. – 2005. – P. 348. [In Russian].8. Lysa A. Late Pleistocene stratigraphy and sedimentary environments of the Severnaya Dvina-Vychegda region in northwestern Russia // Boreas. – 2014. – DOI 10.1111/bor.12080 9. Lyså A. Ice-distal landscape and sediment signatures evidencing damming and drainage of large pro-glacial lakes, northwest Russia // Boreas. – 2011. – 40. – P. 481–497.EXTINCTION AND RECOVERY OF THE CONCHOSTRACAN FAUNA ON THE PERMIAN-TRIASSIC BOUNDARY IN THE LAKES OF NORTHERN EURASIAZharinova V.V., Silantiev V.V.Kazan (Volga region) Federal University, Kazan, RussiaConchostracans are small crustaceans with a bivalve calcium phosphate chitinous shell. They were widespread in the Paleozoic and Mesozoic lakes in the various regions of the Earth (Lutkevich, 1941; Novozhilov, 1950; Novozhilov, 1959; Novozhilov, 1970; Molin, Novozhilov, 1965; Webb, 1978; Tasch, 1987; Lipatova, Lopato, 2000). At the same time, conchostracans were characterized by a high 136rate of evolution and some of their species existed for a short time. A great mass extinction took place at the end of the Permian period. However, many conchostracan species have managed to adapt to the negative environmental events. The most interesting are the changes of conchostracan assemblages at the Permian-Triassic boundary.Late Permian conchostracan assemblage was represented by numerous genera: Limnadia, Cyclestheria, Curvaсornutus, Cornia, Glyptoasmussia, Megasitium, Pseudestheria, Polygrapta, Concilla, Loxomicroglypta, Brachysteria, Palaeolimnadiopsis, Lioestheria, Tigjanium, Gabonestheria, Lioleaiina, Kaltanleaia, Ulugkemia, Estheria, Concherisma, Palaeolimnadiopsis, Estheriella, Cyzicus, Leaia, Pseudoasmussia, Euestheria, Palaeolimnadia. Some species were widely distributed in the Late Permian lakes: Limnadia timanica Mol., Megasitium lundongaense Novoj., Pseudestheria novacastrensis Mitchell, Cyclestheria mitchelliana Novoj., Polygrapta chatangensis Novoj., Kaltanleaia rhodendorfi Novoj. (Webb, 1978; Tasch, 1987). All these species are characteristic only for the Upper Permian deposits, and never occur in the Triassic.Early Triassic conchostracan assemblage includes Limnadia, Palaeolimnadiopsis, Cornia, Lioestheria, Pseudestheria, Cycloestheria, Glyptoasmussia, Loxomicroglypta, Euestheria, Polygrapta, Concherisma, Gabonestheria as well as Late Permian conchostracan assemblage (Webb, 1978; Tasch, 1987; Lipatova, Lopato, 2000). Such genera as Rossoestheria, Caenestheria, Sphaerestheria, Cyclotunguzites, Estheriina, Nestoria, Palaeoleptestheria, Leptestheria, Sphaerograpta, Eulimnadia, Rhynchositum, Vertexia, Cornoleaia, Pseudestheriella are characterized only for Triassic conchostracan assemblage (Lipatova, Lopato, 2000). Many new species first appeared in the Early Triassic. Following species are widely distributed in the Triassic deposits: Lioestheria blomi Novoj., L. propinqua Novoj., Pseudestheria kashirtzevi Novoj., P. vjatkensis Novoj., P. rybinskensis Novoj., P. tumaryana Novoj., P. wetlugensis Novoj., P. sibirica Novoj., P. putjatensis Novoj., Cyclestheria obliqua (Mitchell), C. rossica Novoj., Sphaerestheria ovata Novoj., Cyclotunguzites elongatus Mol., C. gutta (Lutk.), Glyptoasmussia blomi Novoj., G. wetlugensis Novoj., Concherisma tomiensis Novoj., Estheriina aequalis (Lutk.), E. itilica Novoj., Limnadia blomi Nov., Vertexia tauricornis (Lutk.), Brachysteria kotscbetkovi Novoj.; Palaeolimnadiopsis albertii Volz (Lipatova, Lopato, 2000).The wide variety of new species appeared in the Triassic makes it possible to conclude that the conchostracans were highly adaptable to the changing of environmental conditions. The disappearance of Permian species and the first appearance of Triassic ones help to more clearly define the Permian-Triassic boundary in continental formations.The study is supported by the Russian Foundation for Basic Research (project 16-04-01062).REFERENCES1. Lipatova V.V. Triasovie listonogie rakoobraznye Evrazii i ih stratigraphicheskoe znachenie / V.V. Lipatova, A.J. Lopato // GEOS. – 2000. – P. 124.2.  Lutkevich  Е.М.  Phyllopoda  permskikh  otlozhenii  Evropeyskoy  chasti  SSSR  /  Е.М.  Lutkevich  // Paleontologiya SSSR. – 1941. – Vol. 5, issue 10/1. – P. 47.3. Molin V.А. Dvustvorchatye  listonogie  permi  i  triasa  severa  SSSR  / V.А. Мolin, N.I. Novozhilov  // Nauka, – 1965. – P. 116.4. Novozhilov N.I. Recueil D’Articles sur les Phyllopodes Conchostraces / N.I. Novozhilov // Nauka. – 1950. – P. 128.5. Novozhilov N.I. Novye permskie i triasovye Conchostraca iz juzhnoj Belorusii i Priuraliya / N.I. Novozhilov // Materialy k «Osnovam Paleontologii». – 1959. – Vol. 3. – P. 84–103. 6. Novozhilov N.I. Vymershie limnadioidei / N.I. Novozhilov // Nauka. – 1970. – P. 249.7. Tasch P. Fossil Conchostraca of the Southern Hemisphere and Continental Drift / P. Tasch // The Geological Society of America. – 1987. – P. 165.8. Webb J.A. A new Palaeolimnadiopsis (Crustacea: Conchostraca) from the Sydney Basin, New South Wales / J.A. Webb // Alcheringa. – 1978. – Vol. 2. – P. 261–267.

EXTINCTION AND RECOVERY OF THE CONCHOSTRACAN FAUNA
ON THE PERMIAN-TRIASSIC BOUNDARY IN THE LAKES OF NORTHERN EURASIA

http://dspace.kpfu.ru/xmlui/bitstream/net/146554/-1/PLofNE2018_135_136.pdf

EXTINCTION AND RECOVERY OF THE CONCHOSTRACAN FAUNA ON THE PERMIAN-TRIASSIC BOUNDARY IN THE LAKES OF NORTHERN EURASIA

Abstract

Similar works

Full text

Available Versions

Kazan Federal University Digital Repository