NEW RESULTS OF OSL DATING OF QUATERNARY SEDIMENTS IN THE UPPER KATUN’ VALLEY (Gorny Altai) AND ADJACENT AREA
I.D. Zol’nikov1,2, E.V. Deev3,4, S.A. Kotler1,4, G.G. Rusanov5, D.V. Nazarov6,7
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Institute of Archeology and Ethnography, Siberian Branch of the Russian Academy of Sciences, pr. Lavrentieva 17, Novosibirsk, 630090, Russia
3A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
4Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
5Gorno-Altaisk Expedition JSC, ul. Sovetskaya 15, Maloeniseiskoe Village, Altai Territory, 659370, Russia
6A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
7St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, 199034, Russia
Keywords: Quaternary sediments, OSL dating, fluvial and lacustrine deposits, Gorny Altai
Abstract
Several sections have been studied to understand the distribution and interrelation of basic genetic types of Quaternary deposits in the Uimon basin and adjacent area. The OSL date of 101 ± 10 ka from the glaciolacustrine terrace on the northeastern rim of the basin corresponds to the cool substage of MIS 5. The glaciolacustrine sediments of the northern rim are covered with widespread diamictic flows of the outburst draining of the ice-dammed lake. The diamicts are overlain by a subaerial complex of three loesses and three paleosoils. From the OSL loess dates in the range of 43 to 49 ka we infer that the complex formed from the early MIS 3 through the Holocene. This is also supported by radiocarbon dates from fluvial deposits incised into the glaciolacustrine terrace and into megaflood sediments of the final draining of the last paleolake. The OSL dates in the range of 78 to 89 ka from alluvial sediments indicate that postglacial downcutting of the present-day Katun’ valley probably started just after MIS 5. The discrepancy between the beryllium dates from dropstones and Holocene TL-dates of the Katun’ valley floods ranging from 23 to 6 ka can be explained if the younger floods are related to the draining of moraine- and landslide-dammed rather than ice-dammed lakes. The younger floods, though being less voluminous than the glacial megafloods, were capable to produce giant ripple marks.
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