Towards defining the transition in style and timing of Quaternary glaciation between the monsoon-influenced Greater Himalaya and the semi-arid Transhimalaya of Northern India

Abstract

To help delineate the transition in pattern and timing of glaciation between two contrasting regions, Lahul to the south and Ladakh to the north, moraines in the Puga and Karzok valleys of Sanskrit in the Transhimalaya of northern India were mapped and dated using cosmogenic 10Be. In Lahul, Late Quaternary glaciation was extensive with total valley glacial systems being >100 km in extent, whereas glaciation in Ladakh has been comparatively restricted, with glaciers advancing only ∼15 km from the contemporary glaciers during the last 200 ka. In the Puga valley, glaciers advanced >15 km at ∼129 ka and ∼10 km at ∼46 ka, ∼4.2 ka, and ∼0.6 ka. In the Karzok valley, glaciers advanced ∼1 km at ∼3.6 ka. Boulder exposure ages from a large moraine complex in Karzok indicate a glacial advance at ∼80 ka of ∼4 km from the present ice margin. The oldest moraine in Karzok is ∼311 ka, indicating that glaciers advanced >10 km from the present ice margin during or before marine isotope stage 9. The glacial chronology of the two valleys shows a lack of early Holocene glaciation and generally asynchronous glaciation between them. Moraines in the Puga and Karzok valleys broadly correlate with previous studies in the Zanskar Range but the paucity of data for many of the glacial stages across the Zanskar region makes the correlations tentative. The lack of early Holocene glaciation in the Puga and Karzok valleys is in stark contrast to many regions of the Himalaya, including Lahul, and the restricted glacial extent in Zanskar is more similar to the style of glaciation in Ladakh. The similarity between the glacial records in the Puga and Karzok study areas suggests that the transition to Lahul style glaciation is to the south of the Karzok valley, showing that this geographical transition is abrupt.