OSL AND ESR AGES FOR GLACIER FLUCTUATIONS SINCE THE LATE QUATERNARY IN THE XIATE RIVER VALLEY, TIANSHAN RANGE, CHINA

The Xiate River valley originates on the northeastern slope of Tumur-Hantengri Peak, the largest center of modern glaciation in the Tianshan range, Central Asia. Four sets of moraines and associated glaciofluvial deposits are well preserved in this drainage. Dating these landforms allows for reconstruction of the temporal and spatial variations of glaciers in this valley. Five glaciofluvial samples (sand lenses sandwiched within the third moraine complex) were dated using optically stimulated luminescence (OSL) with a single aliquot regenerative (SAR) dose protocol. Seven samples from glaciofluvial deposits and one sample from glacial tills were analyzed by electron spin resonance (ESR) dating of germanium (Ge) centers in quartz grains, which are sensitive to both sunlight and grinding. The ages show general agreement with the geological setting and field investigations. Based on the ages, the available literatures, as well as geomorphic and stratigraphic investigation, we conclude that the first and second sets of moraines were deposited during the Little Ice Age (LIA) and Neoglaciation, respectively. The third moraine complex was deposited during the late period of the last glaciation, corresponding to marine oxygen isotope stage (MIS) 2, and the average age (~17 ka) indicates that this moraine complex was mainly formed during the global Last Glacial Maximum (gLGM). In addition to the deposits in the valley, the well-developed glacial trough and an ESR age (123.9±12.4 ka) of glaciofluvial deposits sandwiched within the fourth moraine complex at the mouth of the Xiate River indicate that a large compound valley glacier developed in this drainage during MIS 6 glaciation.