Luminescence dating of a dammed lake formed by Ashegong landslide on the northeastern Tibetan Plateau

Abstract

A landslide, Ashegong, blocked the Garang River, a tributary of the Yellow River on the northeastern Tibetan Plateau. Six optically stimulated luminescence (OSL) samples were collected from ~35-m-thick lacustrine sediments of the landslide-dammed lake deposited on the bank of Garang River in this study. Samples yielded 40.3 ± 2.7 ka at the top of the lacustrine section and 21.8 ± 1.4 ka at the base of lacustrine layer, which indicated that the dammed lake last approximate 18.5 ka. This landslide dammed lake forming at 40.3 ± 2.7 ka, appeared to be associated with the wetter conditions and extensive rainfall affected by paleomonsoon during marine oxygen isotope stage (MIS) 3 on the northeastern Tibetan Plateau. The blockage by Ashegong landslide had a vital role in shaping river network such as causing the river diversion. Understanding the geomorphic process of landslide damming event is benefit for reflecting paleoclimatic change, tectonic uplift, forecast and mitigate hazards in mountainous area.