Millennial-scale glacier fluctuations on the southeastern Tibetan Plateau during MIS 2

Abstract

The lack of high-resolution, well-dated records hinders our understanding of the climatic factors driving glacier fluctuations on the Tibetan Plateau. The Hengduan Ranges, on the southeastern Tibetan Plateau, are well suited to determining millennial-scale fluctuations in glacier extent. We investigated glacial landforms in the Mt. Gongga and Mt. Siguniang areas and obtained 46 10Be exposure ages. Age peaks and the maximum age reveal two glacier advances on Mt. Gongga (11.26±0.57–11.30±0.92ka, and 17.34±1.38–17.68±1.44ka); and three glacier advances on Mt. Siguniang (16.44±1.87–18.17±1.39ka, 20.48±1.90–22.72±1.74ka, and 29.98±3.96–30.77±2.36ka). We also analyzed a compilation of 181 recalculated 10Be exposure ages from the Hengduan Ranges. Glacier advances roughly correspond to four millennial-scale cold events (the Younger Dryas, and Heinrich events H1, H2 and H3) and are widely distributed in the Hengduan Ranges, which suggests that cooling, rather than precipitation change, was the main driver of glacier advances on the millennial-scale. Variations in monsoonal precipitation, which regulated the amplitude of glacier advances, were indicated by the depression of the equilibrium-line altitude.