RADIOTHERMOLUMINESCENCE DATING OF QUATERNARY SEDIMENTS OF THE TUNKA RIFT
G.F. Ufimtsev, A.V. Perevalov*, V.P. Rezanova*, N.V. Kulagina, I.M. Mashchuk, A.A. Shchetnikov, I.N. Rezanov*, and I.V. Shibanova
Institute of the Earth's Crust, Siberian Branch of the RAS, 128 ul. Lermontova, Irkutsk, 664033, Russia
*Geological Institute, Siberian Branch of the RAS, 6a ul. Sakh'yanovoi, Ulan Ude, 670047, Russia
Keywords: Stratigraphy, Quaternary sediments, radiothermoluminescence dating, lithologic complex, Tunka Rift
Pages: 224-229
Abstract
We have obtained more than 30 radiothermoluminescence (RTL) dates for loose sediments from the Tunka Rift, lithologically divided into sandy, boulder-pebble, terrace, slope, and cover formations. The sandy fluvial sediments are dated to 76.00-31.50 Ka, and the eolian sediments formed from them, to 16.12-8.31 Ka. We have first determined the age of the Mondy moraine in the west of the Tunka Rift - 70.00-72.00 Ka. The age of the ancient alluvium buried under it varies from 101.5 to 132 Ka. The oldest sediments of this complex (153 Ka?) occur in the base of the ancient alluvium of the Ikhe-Ukhgun' River, at its intersection with the Nilov spur. Radiocarbon and RTL dates obtained for the base of the lower terraces of the Irkut River made up of Holocene deposits yield an age of 53.40 and 40.06 Ka, respectively. The lower part of the slope sediments is dated to 22.00 Ka, and the pebbles overlapping the bases and slopes of young volcanoes in the Tunka depression, to 39.00 and 70.00 Ka, respectively.
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