Timing and style of Late Quaternary glaciation in the eastern Hindu Kush, Chitral, northern Pakistan: a review and revision of the glacial chronology based on new optically stimulated luminescence dating

Glacial landforms and sediments provide evidence for two Late Quaternary major glaciations in the eastern Hindu Kush. New optically stimulated luminescence (OSL) dating was undertaken to define the timing of these glaciations and associated sediment deposition. The Drosh Glacial, was defined by OSL dating to have occurred during marine isotopic stage-3, producing an extensive valley glaciation that extended to an altitude of greater than or equal to1300 m above sea level (asl) in the main valley, with an equilibrium line altitude (ELA) depression of similar to1200 m. The Pret Glacial produced a valley glaciation that extended to an altitude of similar to1670 m asl. in the main valley, with an ELA depression of similar to1000 m. The new OSL dating suggests that this glacial stage probably represents several glacial advances that occurred during the latter part of the Last Glacial. Moraines representing two minor glacial advances, the Shandur and Barum Glacial stages, were also recognized near the contemporary glaciers. These probably formed during the Middle/Late Holocene and Little Ice Age, respectively. This study and comparisons with adjacent regions suggest that there was limited glaciation during the global Last Glacial Maximum (LGM) in the Hindu Kush. Deglaciation in the mountain ranges of the Himalayas and the consequent meltwater discharge into the adjacent seas was negligible immediately after the global LGM and it was therefore of minor importance as a forcing factor for global climate change during the end of the last glacial cycle. However, our studies show that glaciation and particularly deglaciation is important in controlling the deposition of thick valley fills and the landscape evolution of the high mountain environments. (C) 2002 Elsevier Science Ltd and INQUA. All rights reserved.