A late Pleistocene glacial maximum during MIS 3 in the Chersky Mountains, central northeast Siberia

The glacial history of northeast Siberia is poorly understood compared with other high-latitude regions. Using ¹⁰Be and ²⁶Al exposure dating together with remote sensing, we have investigated the glacial history of a remote, formerly glaciated valley in the Tas-Kystabyt Range of the Chersky Mountains in central northeast Siberia. Based on measurements from moraine boulders and bedrock samples, we find evidence for deglaciation of the valley 45.6 ± 3.4 ka ago, that is during the peak of Marine Isotope Stage 3. Satellite imagery of the range reveals at least two generations of moraines in other nearby valleys, indicating that multiple stages of glaciation took place across the Tas-Kystabyt Range. Based on calculated equilibrium-line altitudes, we speculate that the outer set of moraines is linked to the 45.6 ± 3.4 ka deglaciation event identified by our dating, while the inner generation of moraines is associated with a younger glaciation event, possibly the last glacial maximum (LGM). Thus, our results reaffirm current impressions that the maximum ice extent during the last glacial cycle was reached before the global LGM in northeast Siberia.