Optical chronology and climatic implication of glacial advances from the southern Ladakh Range, NW Himalaya, India

Abstract

Morphological, sedimentological, and chronological evidence suggests the preservation of three glacial advances of decreasing magnitude in the Puche valley (near Leh), southern Ladakh Ranges. The oldest moraine of Puche Glacier Advance-1 (PGA-1) is optically dated to the early Marine Isotopic Stage (MIS)-2 (31.5 ± 3.3 ka) that persisted until around the global Last Glacial Maxima (LGM) (22.7 ± 1.6 ka). The PGA-2 is optically dated to the post LGM (14.4 ± 1.0 ka) and perhaps was triggered by meltwater pulse (1a?) cooling. The youngest PGA-3 remains undated and could be of Holocene age. The Optically Stimulated Luminescence (OSL) ages suggest a greater role of westerlies in driving the glacier advances during the MIS-2 in the southern Ladakh Ranges and are at variance with the previous suggestions that recommended monsoon driven glacier advances. The OSL ages compared to the previously obtained 10Be surface exposure ages are younger by a magnitude. The study explores probable causes for the variance in two chronologies and suggests employing multiple dating methods to minimize the uncertainty both in terms of age and climatic interpretation.