Paleo-glacial and paleo-equilibrium line altitude reconstruction from the Late Quaternary glacier features in the Pir Panjal Range, NW Himalayas

摘要

Paleoclimatic constraints from mountain ranges separating major climate systems are important in understanding past climatic changes. Using the present-day glacial geomorphology combined with the GlaRe model, the last glacial maximum (LGM) of seven representative valley glaciers of the Pir Panjal Range (PPR), Kashmir Himalaya was reconstructed. The Range lies at the interface of the tropical and temperate climates in the NW Himalayas. The glacier reconstructions showed that the glaciers in the Range advanced similar to 10 km down the present-day cirque margins and attained a thickness of more than 200 m during the LGM. Using six different methods, the equilibrium line altitude (ELA) changes in the selected valleys of the PPR were estimated for which the LGM was reconstructed. ELA depressions calculated for the LGM vary from 374 m to 416 m with a mean of 395 m. The weighted average ELA of the Range lies at an altitude of 3922 m a.s.l showing a general increasing trend from SE to NW of the Range. The published chronology of the loess deposits, a proxy for glacial aridity, shows the evidence of significant glacial advances starting around 350 kya in the valley, which is consistent with the evidence of both the pre- and post-LGM advances observed in this study. The presence of extensive glacier features all across the PPR and the presence of a few small heavily debris-covered glaciers in the Range points towards the rapid deglaciation in the area.