Much late onset of Quaternary glaciations on the Tibetan Plateau: determining the age of the Shishapangma Glaciation using cosmogenic 26Al and 10Be dating

The onset of Quaternary glaciations is a critical event in the climate and tectonic history of the Tibetan Plateau. The Shishapangma Glaciation, defined based on the till deposit from the northern slopes of Mt. Shishapangma, has been identified as the oldest glaciation on the Tibetan Plateau. However, the timing of this glaciation has not been constrained. We measured 10Be and 26Al concentrations of a set of boulders on top of this till and simulated their complex exposure-burial histories. The simulated results indicate that the formation age of this till is likely around 835.2 ± 241.0 ka, representing the minimum timing of glacial onset on the Tibetan Plateau. The Shishapangma Glaciation is apparently much younger than the glacial onset in many other areas of the world, such as Europe and North America, and was likely driven by the coupled effect between tectonic uplift and climate cooling during the early-middle Pleistocene transition.