Multiple paleolakes caused by glacier river-blocking on the southeastern Tibetan plateau in response to climate changes since the last glacial maximum.

The detailed evolution of valley-damming by glaciers on the southeastern Tibetan Plateau, including the large Gega paleolake, is reconstructed based on observed sediment sequences, and optically stimulated luminescence (OSL) dating. In total, six main lithofacies associations are inferred that represent three relevant sedimentary environments associated with the paleolakes, i.e. lacustrine, deltaic and fluvial. Since the local last glacial maximum (LGM), there have been at least three river-blocking episodes and consequent phases of lacustrine development in the Gega and Jiedexiu dammed lakes. They occurred at ca. 25–17 ka, 14–11 ka, and ∼4 ka. Sedimentological evidence shows that the glacier-dammed lakes were not stable; they experienced oscillations of lake level through short-time drainage events. The damming events and subsequent outburst floods were likely triggered by changes in the extent and thickness of glaciers, caused by rapid climatic changes. This seems to be consistent with proglacial lakes occurring elsewhere, although the dynamics of glacier-dammed lakes can be highly variable between catchments and through time due to the influence of climate-dependent factors on the proglacial lakes. • Evolution of valley-damming by glaciers on the southeastern Tibetan Plateau is reconstructed. • Six lithofacies associations are inferred that represent three relevant sedimentary environments. • Damming events and subsequent outburst floods were likely triggered by changes in the extent and thickness of glaciers. • Sedimentological evidence shows that the glacier-dammed lakes were not stable but experienced short-time drainage events. [ABSTRACT FROM AUTHOR]