Contemporary Nonmarine Sedimentation in Soviet Central Asia

Abstract

In Soviet central Asia sediments are being deposited in a wide variety of nonmarine environments. This is an area containing large inland seas similar to those that must have been present in the U.S. several times in the geologic past. Many ancient rock units were formed in epicontinental seas under similar conditions. The Caspian Sea is a huge lake of brackish water on whose margins are deltas of rivers, some draining tectonically active and others tectonically stable areas. Sands, muds, carbonates, and evaporites are being deposited in the sea, and their areal patterns can be related both to bathymetry and oceanography. East of the Caspian is a desert, partially covered by recent windblown sand. Rivers from high mountains on the south flow onto the desert, depositing broad areas of fine-grained, fluvial sand and silt. The Aral Sea is a smaller inland lake with two important deltas and a variety of bottom sediments. These recent sediments have been studied by Russian geologists and oceanographers for more than 30 years. Their work is described in several monographs and many technical articles, and he present paper is a review of their work.