Pre-akchagylian relief of the North Caspian area and Paleo-Volga problem

Abstract

Paleogeomorphological analysis and generalization of borehole data revealed topographic features and drainage pattern, the Paleo-Volga being main artery, which existed during Pre-Akchagylian continental stage of North Caspian area development. Paleotopography reconstruction was based on usage of complex quantitative and qualitative techniques such as study of thickness, lithology, and faces features, stratigraphic completeness of overlying sediments, reconstruction of regional slope and ancient hypsometry, analysis of geological features of the surface of Pre-Akchagylian unconformity etc. A vast endorheic depression of complicated configuration was ascertained at the North Caspian area, a lake basin was situated at its central part, paleovalleys of the Volga, Ural, Big and Small Uzens were falling into the northern part of the basin. Main features of both Pre-Akcha-gylian and present morphoslructures are in close connection with deep structures. The established paleomorphological features of the North Caspian area are of importance for oil and gas prospecting.