Holocene climate variation denoted by Barkol Lake sediments in northeastern Xinjiang and its possible linkage to the high and low latitude climates

The climate over the closed inland Barkol Lake, which is located in northeastern Xinjiang Uygur Autonomous Region, is sig- nificantly influenced by westerly winds today. To improve our understanding of past climate processes in westerly wind influenced regions in northwestern China, a 250-cm sediment section was retrieved from this lake. After taking the carbon reservoir effect into consideration, the chronological sequence of this section was reconstructed based on seven conventional radiocarbon dates of bulk samples, and the bottom age of this section was determined to be about 9400 cal a BP. Multi-proxy datasets, including δ^18Ocar, δ^13Ccar of authigenic carbonate, and total organic carbon were examined using wavelet analysis and singular spectrum analysis methods. Results show that the Holocene in the Barkol Lake region can be divided into four stages： （1） a cold and dry early stage before -8000 cal a BP; （2） a moderately warm and wet middle stage between -8000 and 6000 cal a BP; （3） a warm and dry stage, along with a cooling-wetting tendency from 6000 to 2700 cal a BP; and （4） a fluctuating cooling and wet stage between 2700-800 cal a BP, and a drier stage since 800 cal a BP. The general trend of Holocene climatic changes revealed by Barkol Lake sediments was in agreement with that of adjacent regions. We infer that climatic changes during the Holocene in the Barkol Lake region were influenced not only by high latitudes, especially the North Atlantic region climate, but also tropical low-latitude processes, such as the El Nifio/La Nifia-Southern Oscillation. This study demonstrates that the enhanced activities of ENSO may have played an important role in climatic changes in northeastern Xinjiang during the Holo- cene. Our results also suggest that climatic patterns may be temporally different in the northern Xinjiang area in response to the changing predominant control of either the Westerly or the Asian summer monsoon, depending on the contrast of their relative strengths.