Rapid Lake Level Fall in Pangong Tso (lake) in Ladakh, NW Himalaya: A Response of Late Holocene Aridity

Pangong Tso is a brackish water lake that lies along Pangong strand of the Karakoram strike–slip fault in arid Trans Himalayan region. The geomorphic mapping along the periphery of the lake suggested the presence of four palaeolake level strands located at 6, 4.8, 3.8 and 1.25 m above the present lake level. The gullied periphery expose relict deltaic sediments where sedimentological study enabled us to identify four deltaic lobes that make a classic Gilbert-type delta with well-developed top-set, fore-set and bottom-set. The top-set of the stratigraphically oldest delta lobe that corresponds to the highest lake level shows the presence of freshwater molluscs identified as Radix and a burnt sediment layer (hearth). The charcoal derived from this layer yielded 14C date as 1.7 ka BP and six luminescence ages from different delta lobes suggested that delta evolution and lake level fall of ~6 m took place between ~2–1 ka. Review of palaeoclimate record available from NW Himalaya and Pangong Tso suggests that late Holocene aridity might be responsible for this rapid lake level fall. Sclerochronological analysis carried out on 54 subsamples from three Radix specimens suggested that the modern type of seasonal conditions may have prevailed at ~1.7 ka BP.