Glacial limits, climate and uplift in the Mount Meylixueshan area of Yunnan Province, China: a simulation modelling approach

Abstract

Glacial landforms in the valleys of the Shenchenbao Glacier and the Lailogoru Glacier located on the eastern side of Mount Meylixueshan (6740 m), the highest mountain in Yunnan Province, China, were investigated in the field, and terminal and lateral moraines were identified in each valley. The lowest terminal moraines in these valleys indicate that even at the glacial maximum, the glaciers extended only 2-2.5 km from the present glacier snouts, with altitudes only about 300 m or so lower, despite a snowline lowering of about 600 m during the late Pleistocene. Examination of several possible reasons to account for this limited extension led us to postulate that altitudes were not high enough to nourish glaciers much larger than those of the present. Accordingly, former glacier and topographic conditions were simulated in three steps in order to test this hypothesis, utilizing as control values the climatological data recorded at a nearby station, elevations of the lowest terminal moraines recognized in these valleys (3260 m and 2360 m) and the estimated past equilibrium line altitude of around 4300 m. The results suggest that during the last glacial maximum the mountain was indeed not as high as today, uplift having been at most about 6-700 m during the late Pleistocene and Holocene. Assuming that the maximum glaciation occurred around 50 000 BP, the average annual rate of uplift must have been at most about 12-14 mm yr-1. Although the field data have limitations, the approach is a useful one for separating climate and orogenic effects on glacier variations.