Лëд и снег (Mar 2015)
Glaciation of West Siberia – disputable questions and means of their solution
Abstract
Different approaches to the problem of Quaternary glaciation of the North-West Siberia have been considered in the present paper, in which also analysis of glaciological situation has been done for the region. New obtained materials are given to show evidence of ancient glaciation in the Near-Ural region. As well the middle reach of the Ob’ River along its right-hand bank has been elucidated. The stated data have clearly demonstrated that diverse geological processes occurred to form the Quaternary deposits in the North-West Siberia. Partly it was an activity of glaciers advanced to the lowland from the centers of glaciation in the surrounding mountains. A role of not small importance belonged also to tectonic processes, which Ob’ erosion-accumulative influence and sea transgressions from the Arctic Ocean were connected with. At that all these occurred at the background of deep rock freezing. Study of moraines along the whole length of valleys from the ends of the modern glaciers until the formations of the maximal advance of ancient glaciers confirm our previous conclusion that glaciation also in this part of Siberia could be morphologically of a mountain-valley form only. Developing under conditions of strong permafrost and cryoaridization, the Pleistocene glaciers in the North-West Siberia concentrated in its mountains and did not advance farther than to the foothills. The upland of Siberian Uval, which sometimes has been considered as a moraine relic, presents another formation. It is a completely built system of Ob’ terraces representing the blocks of uplift deposits elevated by tectonics along the renewed ancient faults. The conclusion demonstrates that the subsequent spread of the stone moraine material happened as a result of movement of icebergs which broke of the glaciers with the trapped rock debris during sea transgressions from the Arctic Ocean. It has been established that, according to the results of absolute dating of the studied sediments, the Sartan advance of the glaciers, at any rate, concurred with the sea transgression conditioned by tectonic processes in Arctic.
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