Glacial Geomorphology and Glaciations in the Muzhaerte River Valley,Tianshan Mountains

The Muzhaerte River Valley is located on the southeastern slope of the Tumur Peak, the largest center of modern glaciation in the Tianshan Mountains of China. Four sets of moraines are well-preserved in the valley and on the piedmont. The landforms contain vital information about the variation of the palaeo-environment, and studies on them make it easy to understand the change of ancient glaciers and to reconstruct the palaeo-environment in this region. Electron spin resonance (ESR) dating of a well-exposed section, end moraines and associated outwashes, fluvial sediments on the Kezibulake moraines were carried out using Ge centers in quartz grains, which are sensitive to the sunlight and grinding. Considering the principles of geomorphology and stratigraphy and the available data of the palaeo-environment, some conclusions can be drawn as follows: the first set of moraines, consisting of 3-4 end moraines, were deposited in Little Ice Age; the Tugaibieliqi end moraine was the sediment of the Neo-glacial; the Pochengzi end moraines and the Kezibulake moraines were determined to deposit in the last glaciation and in MIS6. The Pochengzi end moraines and their dates demonstrate that at least three large glacial advances occurred during the last glaciation, corresponding to MIS4, MIS3b and MIS2, respectively. Furthermore the result shows that the glaciers were compound valley ones in MIS2 and MIS3b, while they were piedmont ones in MIS4 and MIS6. The length of the ancient Muzhaerte glacier was about 92～99 km during the Pochengzi glaciation and about 120 km during the Kezibulake glaciation.