Paleogeography of the Sartan Ice Age in the mountains of Northern Cisbaikalia and Northwestern Transbaikalia
F.I. ENIKEEV1, S.A. RESHETOVA1,2
1Institute of Natural Resources, Ecology and Cryology, Siberian Branch, Russian Academy of Sciences, Chita, Russia
2Vinogradov Institute of Geochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: Late Pleistocene, cirques, palaeo snow line, exaration, moraine, reconstruction
Abstract
A palaeogeographic map at a scale of 1:500 000 was built for the territory of Northern Cisbaikalia and Northwestern Transbaikalia during the maximum phase of the Last Glacial Period (MIS-2). Methods of remote identification and spatial registration of glacial landforms with subsequent geomorphological analysis were used. Exaration (cirques and troughs) and accumulative forms (moraines) have been studied, and the values of the depression of the palaeo snow line have been determined. The boundaries of the feeding areas have been reconstructed, the sizes and types of glaciers have been determined, and their correlation has been made in isolated mountain structures. The depression of the palaeo snow line of the mountain structures of the North Baikal Highlands and the ridges of the central part of the Baikal Rift Zone was 1200-1400 m in relation to the modern one. In terms of morphology, the glaciation of the region under consideration is attributed to the mountain-valley and reticulate with several sections of the mountain cover confined to the flattened surfaces of the summit belt of mountain structures. It has been established that the thickness of the glacier everywhere could reach 400-600 m or more. The axial parts of the ridges were mainly subjected to intense glaciation. The largest glaciers covered the Baikal, Barguzinskii, Verkhneangarskii, Delyun-Uranskii, and North and South Muiskii ridges. Together with those flowing down the valleys, they were represented by a single field with huge tongue lobes of outlet glaciers. Less extensive areas of glaciation emerged on the Muyakansky and Ikatsky ridges. Insignificant centers of glaciation are confined to the watershed parts of the Synnyr ridge and the Babanty mountain range. Extremely limited glaciation centers in the rest of the territory, mainly in the pre-rift zone, are associated with protruding peaks of watersheds to the northwest of the Baikal Rift Zone (North Baikal Highlands), and to the south-east towards the Vitim Plateau. An extensive palaeo lake with a level of 860 m, which arose as a result of the damming of the Vitim by the Sygykta glacier in the area of Lake Oron, was reconstructed in the Vitim River basin.
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