TIMING AND EXTENT OF LATE QUATERNARY GLACIATIONS ON THE NORTHERN SLOPES OF MT. SHISHAPANGMA, MONSOONAL HIMALAYAS

Mt. Shishapangma is a key site in the monsoonal Himalayas in terms of the determination of the onset of Quaternary glaciations and its subsequent glacial stages on the Tibetan Plateau. However, few numerical ages have been dated from the glacial landforms and deposits in this area. We constrained the formation ages of a series of moraines on the northern slopes of Mt. Shishapangma using cosmogenic Be-10 and Al-26 dating. The oldest Shishapangma till was dated to around 818.6 ka, corresponding to Marine Oxygen Isotope Stages (MIS) 21. The subsequent glacial stages were dated to 38.0–50.1 ka, 20.4–30.1 ka, 14.8–16.6 ka, 2.6–4.6 ka, and 0.9–1.5 ka, corresponding to MIS 3, MIS 2, Lateglacial, and Neoglacial events, respectively. Differing from many other glaciated areas in the world, the apparently much younger onset timing of Quaternary glaciations on the Tibetan Plateau was likely driven by the coupled effect between tectonic uplift (Kunlun-Huanghe Movement) and climate cooling (“Early–Middle Pleistocene transition”) during MIS 21. Our results also show that the local Last Glacial Maximum (LGM) is during MIS 3 in this area, which was more likely affected by increased monsoon precipitation. The glacial chronology in this area is broadly synchronous with the glacial chronological records across the monsoonal Himalayas, suggesting the important role of monsoon-driven precipitation on glacial dynamics in this region.