UDC 551.79; 551.351.2(262.81); 551.89; 551.468.6
Lobacheva D.M., Badyukova E.N., Makshaev R.R. THE GEOMORPHOLOGICAL INTERACTION BETWEEN THE TERRAIN OF THE BAER KNOLLS AND THE VOLGA PALAEODELTAS AT THE END OF THE KHVALYNSK TIME // Arid Ecosystems. 2023. Vol. 29. № 3 (96). P. 15-23. | PDF
Many geological sections in the ledge of the Lower Volga valley have been actively studied since the end of the 19th century. Results of many years of field work showed that alluvial sediments of the Khvalynsk time (end of the late Pleistocene – early Holocene) are absent in all the studied quaternary sections along the valley. Numerous literary sources, maps and descriptions of wells were used for this research. We conducted geomorphological mapping in ArcGIS using the SRTM DEM and studied many outcrops and wells and carried out field surveys along the Volga valley and in the Baer’s knolls, the giant underwater dunes of the Northern Caspian region. We consider that in the Khvalynsk time the Volga River probably did not run through the site of its current location. In this regard, the question arises of where the Volga channel was located in the North-Western Caspian region. Thus, we propose that the western branch of the Volga ran along the foot of the Eastern Yergeni slopes and eroded the surface of the marine plain, which resulted in the formation of the Sarpinsko-Davanskaya Hollow. Meanwhile, its eastern branches ran into the Khaki Saline, which was one of the estuaries of the Northern Caspian region, where one of the eastern channels of the Paleo Volga probably were flowing into. In the Khvalynsk time, in the lower reaches of the Volga channel there were multiple terminal distributary channels. The large branching delta was much larger (about 200-210 km wide) than the modern delta and somewhat reminiscent of the modern delta of the Lena river in size. Where the modern Volga-Akhtuba floodplain is located now, there was probably a small central branch, in the west there was a Sarpinsky branch, and in the east, an Elton-Khaki branch. They were interconnected by an extensive system of branches, the relief of which is still preserved. At the very end of the Late Khvalynsk time, the Sarpa and Khaki branches began to die off, and most of the water began to run along the central branch, forming the modern Volga-Akhtuba valley.
Keywords: Volga Delta, Caspian Sea, Lower Volga, Baer’s knolls, geomorphology and paleogeography, Late Pleistocene, Khvalynsk time, giant river dunes.
Financing. This work was supported by a grant No. 20-05-00608 “Evolution of the Natural Environment of the Middle Volga Region in the Late Pleistocene: Chronology, Climatorythmics and Correlation with the Events of the Caspian Region”.