Timing of multiple late Quaternary glaciations in the Hunza Valley, Karakoram Mountains, northern Pakistan: Defined by cosmogenic radionuclide dating of moraines

Abstract

Moraines and associated landforms in the upper Hunza Valley, Karakoram Mountains, northern Pakistan, provide an excellent record of multiple glaciations. During the late Quaternary, glaciers advanced at least eight times. By using 10 Be and 26 Al surface-exposure dating on moraine boulders and scoured bedrock, we determined the timing of glaciation for four of these glacial advances: ca. 54.7‐43.2 ka (Borit Jheel glacial stage), ca. 25.7‐21.8 ka (Ghulkin I glacial stage), ca. 18.4‐15.3 ka (Ghulkin II glacial stage), and ca. 10.8‐9.0 ka (Batura glacial stage). For two of the older advances, the Yunz and Shanoz glacial stages, our data set a limit of .60 ka. Although, at present, the uncertainties in dating make it impossible to describe unequivocally the climate processes controlling glaciations in the Hunza Valley, the results suggest that precipitation changes related to oscillations in the southwest Asian monsoonal system combine with cooling that is broadly associated with Heinrich events to cause glacial advances in this region.