LATE QUATERNARY REGRESSIONS IN THE CASPIAN SEA
In the depositional series of the Northern Caspian the regressive intervals are represented by paleodepressions and erosional landforms distinctly seen in the seismic stratigraphic profiles. As follows from the composition of organic remains, there existed lakes with fresh water and wetlands. The oxygen isotope analysis lends support to the opinion that the Volga inflow influence on the Caspian area increased.
The Atelian pollen assemblages are indicative of rather diversified landscapes north of the Caspian Sea – from forests dominated by conifers to periglacial forest-steppe and tundra-forest-steppe. The age of final phase of the regression was determined as 44–42 ka BP (first half of the MIS 3). Well-developed cryogenic wedges found at the base of Atelian series and deeply penetrating into the underlying deposits (dated to MIS 5) suggest the accumulation of the subaerial Atelian deposits to begin at the cold (glacial) epoch MIS 4.
The Mangyshlak deposits were formed during arid conditions. The saturation of water with carbonates during the accumulation of sapropel led to the deposition of chemogenic carbonates. The Mangyshlak deposits contain few faunal remains compared to the overlying and underlying transgressive sequence but include freshwater and terestrial molluscs. The absence of the Didacna genus is its characteristic feature. Dating defines the age of the regression to be between 11,9 and 10,5 ka BP (the beginning of MIS 1).
The work is in the fram of RFBR Project 20-39-70020. Isotope analysis executed on the RFBR Project 20-35-90020.