Provenances of Upper Quaternary sediments in the Northern Caspian Sea

This paper presents a generalization of the clay minerals composition in the sediments of the KOR-3 core located in the central part of the Northern Caspian Sea (19 samples). The history of changes in the different river basins contribution to the sedimentary supply in the central part of the Northern Caspian Sea could be traced by changes in clay mineral ratios in the Upper Quaternary sediments. Changes in the ratio reflect differences in material sources during the first and second stages of the Khvalynian transgression of the Caspian Sea — one of the most controversial stages in the history of the Caspian Sea. Consequently, our conclusion is that there were different causes of sea-level uprise at different stages of the transgression. The subsequent events (deep Mangyshlak regression and New Caspian transgression) are not associated with abrupt changes in the inflow of rivers into the Northern Caspian Sea, according to the composition of clay minerals.