GEOLOGICAL MARKERS OF THE UPPER PLEISTOCENE DEPOSITS IN MAIN RIVER VALLEYS OF WESTERN SIBERIA

Abstract

During the second half of the 20th century by the end of the first quarter of the 21st century the problem of differentiation and correlation of the main rivers of Western Siberia (primarily the Ob and Yenisey) valleys sediments was intensively discussed. Traditionally, the regional Quaternary history of the river valleys was considered as the “terrace flight” paradigm. According to it in the Neogene-Quaternary time alluvial terraces formed by sequentially from the older upper to the younger lower ones. It was considered that terrace formed by neotectonics, paleoclimate dynamics changed the fullness of the rivers, advance of the sea and dereliction influenced on base of erosion and blocking river valley by northern glaciers. As a result, in outside glacier zone appeared barrier basins and periglacial alluvium. However, on the official maps of the Quaternary deposits the heights, age and even the number of terraces differ significantly. Nowadays a lot of data are contrary to theory about flight consistently carved cycloclimatic terraces and periglacial alluvium facies replacing the ice-dammed northern lakes in the south of Western Siberia. In the article it was performed the updated concept of the sedimental structure of the Upper Neopleistocene in the main valleys of the region and taking into account data on glacier outburst floods from intermountain area to the plain. Its intensive erosional and accumulative activity has so far been underestimated.