GLACIATION OF THE LOPU KANGRI AREA, CENTRAL GANGDISE RANGE: TIMING THE EXTENTS

The Lopu Kangri area is located in the central Gangdise Range, which is a transient zone of Asian monsoon system. We investigated the glaciation history in the Gaerqiong valley and the Kabugu valley in the eastern slope of Lopu Kangri using ¹⁰Be exposure dating. Five glacial events were constrained to 0.19 ± 0.04 ka, 0.28 ± 0.03 to 0.29 ± 0.09 ka (Little Ice Age, LIA), 1.7 ± 0.2 ka, 2.3 ± 0.2 ka to 2.7 ± 0.3 ka (Neoglacial), 7.3 ± 0.6 ka to 19.0 ± 1.7 ka, 11.9 ± 1.3 to 51.1 ± 4.6 ka and 193.9 ± 19.0 to 297.6 ± 3.0 ka. Comparing with previous studies in the eastern and western Gangdise, Nyainqentanglha and the Himalayas, we suggest that the glaciation in the Neoglacial and the LIA was caused by cold and humid climate.

We also estimated the change in glacier area and Equilibrium Line Altitude (ELA) since the LIA across the Gangdise Mountains. A total of 1216 glaciers were investigated, they retreated with an average length reduction of 40.1-42.7%, area loss of 43.5-46.0%, or an ELA increase of 44-47 m. The ELAs have an increasing trend from southeast to northwest, both at present and in the LIA stage. ΔELA roughly decreases from eastern to central Gangdise, and then increases westward, with the averages of 55-60 m, 36-41 m, 43-49 m in the eastern, central and western parts of the mountains. Our results suggest that, 39.8% of area loss can be explained by glacier elevation, area and slope. But only 13.2% of ΔELA can be explained by glacial geometric, topographical or locational parameters. The spatial pattern of modern ELA of this area is contrary to that of precipitation, implying precipitation is a main control on ELA distribution. Comparing our results with the studies in the other plateau regions, as well as the records from lake sediment and ice cores, and concluded that our study area are dominated by Indian Monsoon and the Westerlies, which control the precipitation pattern. In contrast to the northern and southern section, their influence on the central Gangdise is very limited, and glaciers in this section are steadier, in term of length reduction, area loss and mass balance. Meantime, topography can also influence glacier change by causing shielding effect or changing radiation absorption.