ON PALEOGEOGRAPHY OF THE LOWER VOLGA RIVER AREA DURING THE LAST GLACIAL EPOCH

The upper Pleistocene deposits of the Lower Volga River region consist of the upper Khazarian, Akhtubian, Atelian and Khvalynian sediments, which are represented by different facies – from marine to continental ones. The paleogeographical analyses of them allowed us to reconstruct the history of the Lower Volga region during the last glacial epoch.

The last glacial epoch was characterised by the accumulation of the Akhtubian sands in the Volga River valley. Ice “wedges” in their basis, and periglacial vegetative spectra are the evidences of glacial epoch. Akhtubian sands are changed by Atelian formation. These continental deposits are either alluvial or sub-aerial in origin. The fossil molluscs, pollen of taiga vegetation, a complex of mammals are paleontologic arguments of a cold epoch. The capacity of deposits and the formation of three horizons of soils testify a long epoch covering the most part of Valdai Glacial epoch. Caspian Sea was characterized by a regressive condition during the most part of the Akhtubian-Atelian epoch.

The Khvalynian Caspian deposits were formed during the second half of the Valdai epoch, in conditions of humidifying and flowing from a land. Transgression developed with two stages. The early Khvalynian transgressive stage was maximal one. The valley of the Volga River has turned in estuarian basin, which reached almost 600 km upwards on the river. The sea fauna and microfauna characterized the cold and freshened waters. According to the fossil pollen, this was a cold epoch with taiga vegetation, later replaced by steppe herbaceous vegetation. The early Khvalynian waters had a drain in the New Euxinian basin (Black Sea) basin.

The level of the late Khvalynian basin did not exceed a zero mark. Volga River flowed into it by two basic arms, each of them had the branched delta. The water of basin have been rather freshened, but shells of the molluscs specifies rise in temperature of water. Palynological data indicate general warming in the region. The Late Khvalynian regression coincided with increasing aridity in the Caspian region and the beginning of the postglacial epoch. All cycle of paleoevents (Akhtubian – late Khvalynian) took place during the Valdai glacial epoch.