Features of Paleogeography of the Ubsunur Basin. 2022

Studies of the paleogeography of the Ubsunur basin, located on the territory of Northwestern Mongolia and southern Tuva, were based on the discovery of buried ice veins under Aeolian sediments in the lake area. Khara-Nur of the eastern mountain frame of the Basin of the Great Lakes of Western Mongolia. Along the periphery of the sand deposits on the satellite images, the outlines of fields were recognized, the natural irrigation of which, in our opinion, was due to the melting of the mentioned ice. In the river valleys of the northern border of the Ubsunur basin, in its foothill part, deposits similar to glacial ones were found, which suggested the presence of Pleistocene glaciers extending into its flat territories. Based on this, it was also assumed that, by analogy with the Khara-Nur, peculiar sand massifs located in the basin could preserve relic zones of permafrost, the melting of which contributed to the moistening of local landscapes. Such humidification zones are recognized on satellite images. There are no glacial deposits in this territory in geological legends. At this stage of research, we confirm the presence in the past of low-power glaciers on the designated area, which was caused by mountain-forming processes, the eruption of quaternary volcanoes on the territory of Tuva and Mongolia. Tectonic processes contributed to the damming of the Tes-Khem River, the main waterway flowing along the northern mountain rim of the basin, the formation of dammed lakes and their subsequent descent. The extended peculiar sand massifs located in the basin within the Agardag mountain range, previously considered as fluvioglacial deposits, are the result of the descent of the dammed lakes.