Optically stimulated luminescence chronology and geomorphic imprint of Xiazangtan landslide upon the upper Yellow River valley on the northeastern Tibetan Plateau

Landslides provide a means to study tectonic and climate forcing on hillslopes in mountainous terrain. Landslides are common in the upper Yellow River valley on the northeastern Tibetan Plateau, some of which even blocked the Yellow River. However, uncertainty remains on the trigger factors for these palaeolandslides, and emplacement timing of palaeolandslides could be essential to resolve these issues. In this study, single aliquot regeneration protocols of quartz was applied to a perched lake overlying Xiazangtan landslide mass. Optically stimulated luminescence ages at the basal of this lacustrine lake constrained a minimum age for this landslide, reflecting that Xiazangtan landslide that occurred at or before 44.9 ± 3.2 ka, the marine isotope stage (MIS) 3. Wetter conditions and extensive rainfall in MIS 3 may have resulted in a rapid growth of pore pressure and loss of the apparent cohesion of thin soils, eventually causing the failure of Xiazangtan landslide, while earthquake could not be ruled out in such a tectonically active area. Xiazangtan landslide plays a significant role in shaping mountainous topography. This landslide, for instance, reduced hillslope gradients along the slope profile, added noise to river longitudinal profile development, and interrupted the formation of fluvial terraces by slowing down fluvial bedrock incision.