The Positions of the Channels of the Volga Paleodelta at the End of the Khvalynian Time According to Geomorphological Data

Abstract

Many geological sections along the Lower Volga valley have been actively studied since the end of the 19th century. The results of field work showed that in all the studied Quaternary sections along the Lower Volga valley, alluvial deposits of the Khvalynian time (the end of the Late Pleistocene) are absent. Geomorphological mapping was carried out and many outcrops along the Volga valley and on the Baer knolls were studied. In the Khvalynian time, the Volga most likely did not flow in its present position. The purpose of this article was to determine the locations of the paleochannels of the Volga on the basis of geomorphological data, in particular, the spatial location and morphology of the Baer knolls. A large multi-branched delta (about 200–210-km wide), probably similar in size to the modern Lena delta, was located significantly to the north of the modern one. The delta existed in the form of a series of small and large branches; on the site of the modern Volga-Akhtuba there was probably a small central branch, the Sarpa branch was located in the west, and the Elton-Khaki branch was located in the east. At the beginning of the Holocene, the Sarpa and Khaksky branches began to die off, and most of the water began to rush along the central branch, forming the modern Volga-Akhtuba valley. The Sarpa-Davan channel system continued to be active in the period after the formation of the Baer knoll complex, that is, at the beginning of the Holocene during the Mangyshlak regression.