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Geography and Natural Resources

2023 year, number 1

The age and formation mechanisms of Baikal terraces

E.E. KONONOV
V.B. Sochava Insitute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: Baikal, terrace complex, genesis, climate, hypsometry, discussion

Abstract

A critical analysis is made of the available published ideas concerning the role of the leading factors in the formation of Baikal terraces: tectonics, climatic fluctuations of the lake level, and a periodic change of the location of the drain slot. The inconsistency of the assumptions about the dominant role in the creation of lake terraces of different levels (including underwater terraces) of the change of location in the Late Pleistocene of the Irkut direction of the Baikal water discharge to the Angarа direction is shown. These data show that during periods of cooling of the Late Pleistocene, the lake level could presumably decrease by no more than 40-45 m, and its rise during periods of warming could not be higher than the runoff thresholds of the Baikal waters of that time, which rules out the possibility for the formation of a complex of high terraces. The denial of the role of tectonic movements in the formation of lake terraces is in complete contradiction with the actual tectonic activity of the Baikal Depression proven in numerous scientific papers. It is established that tectonic movements play a major role in modeling the relief of the lake basin and determine the hypsometric position of terraced surfaces and their deformation. The available, very few, definitions of the age of terraces do not allow for their correlation. The chief reason for the disagreement on the Baikal terraces is the lack of systematic specialized research on this problem.