STRUCTURE OF THE HOLOCENE SEDIMENTARY SERIES OF THE NORTHERN CASPIAN SEA AS A REFLECTION OF CLIMATE AND SEA LEVEL CHANGES

Oscillations of the Caspian Sea level under climate changes of different scale and direction during the Holocene and their reflection in the structure of the sedimentary series of the Northern Caspian Sea area were studied through the analysis of two-frequency seismoacoustic profiles and the drill cores using lithological, malacofaunistic, and geochronological (radiocarbon) methods The analysis of the Holocene sedimentary series of the Northern Caspian Sea revealed palaeogeographic events of different scale, namely the Mangyshlak regression and the multiple-stage New Caspian transgression. Both resulted from climatic changes varying in scale and direction. The Mangyshlak regression down to –90 m occurred in the Boreal period (according to the Blytt-Sernander scheme) of the Early Holocene characterized by rather high level of heat supply and aridity. A short-term sharp cooling known as «8200 event» and a simultaneous increase in aridity resulted in the maximum drop of the Caspian Sea level at the final stage of the regression. The New Caspian transgression had three transgressive stages: the first one developed under warm and wet climate of the Holocene Atlantic optimum; the second one was a response to the Subboreal cooling and increasing moisture supply on the East European Plain; the third stage is characterized by two groups of dates 1700–1100 and 700–360 yr BP and the hiatus between them suggests a lower level of the Caspian Sea at the warm and dry medieval interval, while the second group of the dates corresponds to the Caspian Sea level rise during cool and wet climate of the Little Ice Age. The transgressive stages are characterized by different mollusk assemblages: slightly brackish-water species were dominant in the early New Caspian basin, the presence of Didacna genus mollusks was insignificant; the middle transgressive stage is noted for widely spread mollusks of Didacna genus and the advent of Cerastoderma glaucum; the species composition of the late transgressive stage is similar to the present-day one and at the latest stages of its evolution some of the Black Sea species appeared, such as Mytilaster lineatus (brought in by chance with ships in the early 20th century) and Abra ovatа (acclimatized intentionally as a sturgeon feed in the mid-20th century). The regressive phases when the sea level went down to 9 m corresponded to the Subboreal thermal maximum of the Holocene and the period of warming and decreasing rainfall in the Volga drainage basin.

Northern Caspian Sea, Holocene, climate changes, sediment structure

1. Abramova T.A. Rekonstruktsiya paleogeograficheskih usloviy epoh chetvertichnyh transgressiy i regressiy Kaspiyskogo morya (po dannym paleobotanicheskih issledovaniy) [Reconstruction of paleogeographical conditions of the epochs of Quaternary transgressions and regressions of the Caspian Sea (by the data of paleobotanical research)]. Thes. of PhD in Geography dissert. M., 1974. 24 p. (in Russian).

2. Alley R.B., Mayevski P.A., Sowers T. et al. Holocene climatic instability: a prominent, widespread event 8200 yr ago // Geology. 1997. № 25. P. 483–486.

3. Bezrodnykh Yu.P., Delia S.V., Romanyuk B.F., Fedorov V.I., Sorokin V.M., Luksha V.L. Mangyshlakskiye otlozheniya (golotsen) Severnogo Kaspiya [Mangyshlakian deposits (Holocene) of the Northern Caspian Sea] // Stratigraphy. Geological correlation. 2014. V. 22. № 4. P. 88–108 (in Russian).

4. Bezrodnykh Yu.P., Sorokin V.M. On the age of the Mangyshlakian deposits of the Northern Caspian Sea // Quaternary Research. 2016. № 85(2). P. 245–254.

5. Bolikhovskaya N.S. Evolyutsiya klimatov i landshaftov Nizhnego Povolzhiya v golotsene [Evolution of climate and landscapes of the Lower Volga River area in the Holocene] // Vestnik Moskovskogo Unviersiteta. Ser. 5. Geographiya. 2011. № 2. P. 13– 27 (in Russian).

6. Bolikhovskaya N.S., Kasimov N.S. The evolution of climate and landscapes of the lower Volga region during the Holocene // Geography. Environment. Sustainability. 2010. № 2(3). P. 78–97.

7. Borisova O.K. Lanschaftno-klimaticheskie izmeneniya v golotsene [Landscape and climatic changes in the Holocene] // Izv. Russian Academy of Sciences. Ser. Geogr. 2014. № 2. P. 5–20 (in Russian).

8. Bukreeva G.F., Vronsky V.A. Palinostratigrafiya i paleogeografiya Kaspiyskogo morya v golotsene po rezultatam modelirovaniya paleoklimata [Palynostratigraphy and paleogeography of the Caspian Sea during the Holocene by results of the paleoclimate modeling] // Palynology in Russia. 1995. V. 2. P. 12–25 (in Russian).

9. Danzeglocke U., Jöris O., Weninger B., CalPal_2007online. http://www.calpal_online.de/. Fedorov P.V. Pleystotsen Ponto-Kaspiya [Pleistocene of the Ponto-Caspian Sea]. M.: Nauka, 1978. 165 p. (in Russian).

10. Hotinsky N.A. Golotsen Severnoy Evrazii [Holocene of the Northern Eurasia]. M.: Nauka, 1977. 200 p. (in Russian).

11. Hoogendoorn R.M., Boels J.F., Kroonenberg S.B., Simmons M.D., Aliyeva E., Babazadeh A.D., Huseynov D. Development of the Kura delta, Azerbaijan; a record of Holocene Caspian Sea level changes // Marine Geology. 2005. № 222–223. P. 359–380.

12. Khrustalyov Yu.P., Kovalyov V.V. Osnovnye etapy pozdnepleistotsenovoi i golotsenovoi istorii Severnogo Kaspiya [The main stages of the late Pleistocene and Holocene history of the Northern Caspian Sea] //Paleogeography and geomorphology of the Caspian region during the Pleistocene]. M.: Nauka, 1991. P. 106– 116 (in Russian).

13. Klimanov V.A., Hotinsky N.A., Blagoveshchenskaya N.V. Kolebaniya klimata za istoricheskiy period v tsentre Russkoy ravniny [Fluctuations of climate for the historical period in the center of East European Plain] // Izv. Russian Academy of Sciences. Ser. Geogr. 1995. № 1. P. 89–96 (in Russian).

14. Kroonenberg S.B., Abdurakhmanov G.M., Badyukova E.N., van den Borg K., Kalashnikov A., Kasimov N.S., Rychagov G.I., Svitoch A.A., Vonhof H.B., Wesselingh F.P. Solar-forced 2600 BP and Little Ice Age highstands of the Caspian Sea // Quaternary International. 2007. № 173–174. P. 137–143.

15. Kroonenberg S.B., Kasimov N.S., Lychagin M.Yu. The Caspian Sea, a natural laboratory for sea-level change // Geography, Environment, Sustainability. 2008. № 1(1). P. 22–37.

16. Kuzmin Ya.V., Nevesskaya L.A., Krivonogov S.K., Burr G.S. Apparent 14C ages of the ‘pre-bomb’ shells and correction values (R, _R) for Caspian and Aral Seas (Central Asia) // Nucl. Instrum. Methods Phys. Res. 2007. № 259. P. 463–466.

17. Leroy S.A.G. Palaeoenvironmental and palaeoclimatic changes in the Caspian Sea region since the Lateglacial from palynological analyses of marine sediment cores // Geography, Environment, Sustainability. 2010. № 2. P. 32–41.

18. Leroy S.A.G., Tudryn A., Chalie F., Lopez-Merino L., Gasse F. From the Allerшd to the mid-Holocene: palynological evidence from the south basin of the Caspian Sea // Quaternary Science Reviews. 2013. № 78. P. 77–97.

19. Maev E.G. Fazy mangyschlakskoy regressii Kaspiyskogo morya [Phases of the Mangyshlak regression of the Caspian Sea] // Vestnik Moskovskogo Unviersiteta. Ser. 5. Geographiya. 2009. № 1. P. 15–20 (in Russian).

20. Mangerud J., Andersen S.T., Berglund B.E., Dorrner J.J. Quaternary stratigraphy of Norden, a proposal for terminology and classification // Boreas. 1974. № 3. P. 109–128.

21. Mann M.E., Zhang Z., Rutherford S. et al. Global signatures and dynamical origins of the little ice age and medieval climate anomaly // Science. 2013. № 326. P. 1256–1260.

22. Novenko E.Yu. Izmeneniya rastitelnosti i klimata tsentralnoy i vostochnoy Evropy v pozdnem pleistotsene i golotsene v mezhlednikovye i perehodnye etapy klimaticheskih macrotsiklov [Changes of vegetation and climate of the Central and Eastern Europe during the late Pleistocene and the Holocene in the interglacial and transitional stages of climatic macrocycles]. Thes. of the Dr. Sci. in Geography dissert. M., 2016. 44 p. (in Russian).

23. Panin A., Fuzeina Yu., Karevskaya I., Sheremetskaya E. MidHolocene gullying indicating extreme hydroclimatic events in the centre of the Russian Plain // Geographia Polonica. 2011. № 84. Special Issue. Part 1. P. 95–115.

24. Panin A., Matlakhova E. Fluvial chronology in the East European plain over the last 20 ka and its palaeohydrological implications // Catena. 2015. № 130. P. 46–61.

25. Richards K., Mudie P., Rochon A., Bolikhovskaya N., Hoogendoorn R., Verlinden V. Late Pleistocene to Holocene evolution of the Emba delta, Kazakhstan, and coastline of the northeastern Caspian Sea: Sediment, ostracods, pollen and dinoflagellate cyst records // Palaeogeography, Palaeoclimatology, Palaeoecology. 2017. № 468. P. 427–452.

26. Rychagov G.I. Urovenny rezhim Kaspiyskogo morya during the last 10 000 let [Sea level mode of the Caspian Sea for the last 10 000 years] // Vestnik Moskovskogo Unviersiteta. Ser. 5. Geographiya. 1993. № 2. P. 38–49 (in Russian).

27. Rychagov G.I. Holocene oscillations of the Caspian Sea, and forecasts based on palaeogeographical reconstructions // Quaternary International. 1997. № 41/42. P. 167–172.

28. Sorokin V.M., Yanina T.A., Bezrodnykh Yu.P., Romanyuk B.F. Stroyeniye, vozrast i usloviya nakopleniya novokaspiyskih otlozheniy Severnogo Kaspiya [Structure, age and conditions of accumulation of the New Caspian deposits of the Northern Caspian Sea] // Questions of geomorphology and paleogeography of sea coasts and shelf. M.: Geographical faculty of MSU, 2017. P. 133– 136 (in Russian).

29. Svitoch A.A. Golotsenovaya istoriya Kaspiyskogo morya i drugih okrainnyh basseinov Evropeiskoy Rossii: sravnitelniy analiz [Holocene history of the Caspian Sea and other opened basins of the European Russia: comparative analysis] // Vestnik Moskovskogo Unviersiteta. Ser. 5. Geographiya. 2011. № 2. P. 28– 37 (in Russian).

30. Thomas E.R., Wolff E.W., Mulvaney R. et al. The 8,2 ka event from Greenland ice cores // Quaternary Science Reviews. 2007. № 26. P. 70–81.

31. Varushchenko S.I., Varushchenko A.N., Klige R.K. Izmenenie rezhima Kaspiyskogo morya i besstochnykh vodoemov v paleovremeni [Change of the mode of the Caspian Sea and drainless reservoirs in paleotime]. M.: Nauka, 1978. 238 p. (in Russian).

32. Velichko A.A. Evolutsionnaya geografiya: problemy i rescheniya [Evolutionary geography: problems and decisions]. M.: GEOS, 2012. 563 p. (in Russian).

33. Vronsky V.A. Stratigrafiya i paleogeografiya Kaspiyskogo morya v golotsene [Stratigraphy and paleogeography of the Caspian Sea during the Holocene] // Izv. Russian Academy of Sciences. Ser. Geol. 1987. № 2. P. 73–82 (in Russian).

34. Wanner H., Beer J., Butikofer J. et al. Mid- to Late Holocene climate change: an overview // Quaternary Science Reviews. 2007. № 27. P. 1791–1828.

35. Yanina T.A., Svitoch A.A., Wesselingh F.P. Bioraznoobraziye malakofauny Kaspiyskogo morya v golotsene [Biodiversty of malacofauna of the Caspian Sea in the Holocene] // Vestnik Moskovskogo Unviersiteta. Ser. 5. Geographiya. 2011. № 2. P. 38– 48 (in Russian).