Late Pleistocene glaciers in Darhad Basin, northern Mongolia.

Late Pleistocene glaciers around Darhad Basin advanced to near their maximum positions at least three times, twice during the Zyrianka glaciation (at ∼ 17-19 ka and ∼ 35-53 ka), and at least once earlier. The Zyrianka glaciers were smaller than their predecessors, but the equilibrium-line altitude (ELA) difference was < 75 m. End moraines of the Zyrianka glaciers were ∼ 1600 m asl; ELAs were 2100-2400 m asl. 14C and luminescence dating of lake sediments confirm the existence of paleolake highstands in Darhad Basin before ∼ 35 ka. Geologic evidence and 10Be cosmic-ray exposure dating of drift suggests that at ∼ 17-19 ka the basin was filled at least briefly by a glacier-dammed lake ∼ 140 m deep. However, lake sediments from that time have not yet been recognized in the region. A shallower paleolake briefly occupied the basin at ∼ 11 ka, but between ∼ 11 and 17 ka and after ∼ 10 ka the basin was probably largely dry. The timing of maximum glacier advances in Darhad appears to be approximately synchronous across northern Mongolia, but different from Siberia and western Central Asia, supporting the inference that paleoclimate in Central Asia differed among regions.