Pleistocene glaciations of the high mountain ranges of Northern Cisbaikalia
R.Ts. BUDAEV
Dobretsov Geological Institute, Siberian Branch, Russian Academy of Sciences, Ulan-Ude, Russia
Keywords: Baikal Ridge, Barguzin Ridge, Pleistocene glaciations, exaration relief, thermoluminescence dating
Abstract
Results of comprehensive geochronological, geological and geomorphological studies of the Pleistocene glaciations of the Baikal and Barguzin Ridges are presented. In spite of the fragmentation and disunity of geological cross-sections of glacier formations of Pleisatocene glaciations on these ridges, the factual evidence accumulated to date concerning the morphology of the glacier relief, the geological cross-sections of glacier formations and scant absolute datings make it possible to generalize these data. Field measurements were made in the foothill area of the aforementioned ridges as well as in the Baikal and Barguzin rift valleys. Remote geomorphological studies were used extensively and included the analysis of topographic maps of various scales, interpretation of aerial and satellite photographs, and aerial visual flights on airplanes and helicopters with landings to refine interpretation data, study geological cross-sections and collect samples. Thermoluminescence dating confirmed that the remains of large theriofauna found on a high 50-80-meter terrace in the delta of the Tyya are of Middle Pleistocene age. Single dates were obtained from the deposits of the Tyya glacier of the maximum Middle Pleistocene glaciation, Eopleistocene sediments lying at the base of the Rel-Tyya intermediate stage, as well as from the terminal moraines of the Ulyugninskii and Upper Kurumkanskii glaciers located on the eastern slope of the Barguzin Ridge. Material presented confirms the synchronism of glaciations on the Barguzin Ridge and on other high-mountain ranges of Northern Cisbaikalia and the Stanovoi Highlands. They are compared with the glaciations of Western Siberia. The first Mid-Pleistocene glaciation was semi-cover (reticulated), the second and third were of the mountain-valley type, and the fourth glaciation was of the cirque type. The reliability of the identification of glacial epochs is confirmed by data of morphological studies of the exaration relief and glacial formations, material of the study of the geological structure of the terminal moraine lines and fluvioglacial deposits, the age of which is confirmed by megafauna finds and thermoluminescence dating.
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