Geomorphological investigations and luminescence dating in the southern part of the Khangay and the Valley of the Gobi Lakes (Central Mongolia)

Geomorphological investigations in the catchment area of the Baydragiyn riv er along the southern slope of the Khangay and in the Valley of the Gobi La kes in western Mongolia provide evidence for Late Quaternary glaciations an d lake-level changes. Thermoluminescence (TL) and infrared optically stimul ated luminescence (IRSL) dating of aeolian and colluvial sediments from the central Khangay place the sediments that overlie fluvial and glaciofluvial terraces in the Holocene. An age of 21 ka is determined for a sand deposit overlying the terrace that is related to the last glacial ice-margin. Lacu strine sediments from higher beach lines in the Valley of the Gobi Lakes pr ovide evidence for a slightly more humid period around 1.5 ka, and a larger extent of the lakes in the Early Holocene at about 8.5 ka, as also reporte d from other parts of Central Asia. Remnants of lacustrine sediments buried by alluvial gravel, and indicating a huge palaeolake in the basin of the G rog Nuur, however, date to the early stage of the last glaciation around 70 ka. Copyright (C) 2001 John Wiley & Sons, Ltd.