ИСТИНА

Manych-strait connected Black sea and Caspian Sea in Pleistocene is a great event in the history of the Ponto-Caspian region. The strait located within such geological structure as Manych Depression which is extended sublatitudinally from the west coast of Northern Caspian to the north-west of the Azov sea. The existence of the Manych-strait is essentially for the stratigraphy and paleogeography. There were several stages when marine waters spilled over from Black sea to Caspian and alternatively. Due to the alternation of sedimentary layers it is possible to correlate pleistocene deposits and paleogeographic events. Nowadays there are a lot of materials and data about the history of Manych-strait. In the profile are distinguished interbedding marine deposits with lacustrine and alluvial formations and subaerial deposit on top. The main question is the paleogeographical reconstruction and chronological timeframe of main events of Late Quaternary. We try to solve this problem using our new data and elaborating available information. The preliminary scheme of the sequence of paleogeographic events in Pleistocene is complied. The beginning of Late Pleistocene is marked by the penetration of marine water deep within the Manych Depression during the Black Sea interglacial transgression (Karangat Trangression, MIS 5e). The character trait of marine water through this period is relatively high salinity (18-20 ‰), that favors the development of Black Sea mollusks. During the transition to the glacial epoch (MIS 5d-a) the marine waters oh Karangat bay had begun retreated back into the Black Sea basin. In the end of this stage there was a strait called Hirkanian, which had desalted brackish waters (8-10‰) of the Caspian sea. The marine epoch in the central part of the Manych depression changed to the durable lacustrine phase of development in the second half of Late Pleistocene (MIS 4-3), Burtass lake existed there. In the beginning of its existence it was flowing through (it so because of the major of fresh- and calmwater mollusks in the base of the layer). During the continental stage there was an active erosion damage of the burtass deposits. Through this period were formed specific landscape forms – extended ridges – which finally formed in the epoch of degradation of the last glaciation and Khvalynian water removing to the Black Sea basin. After the closing of the Khvalynian strait began the continental epoch, through this time there were forming the subaerial stage, which is continuous nowadays. Research was supported by the Russian Science Foundation, project 16-17-10103.