The Sedimentary Paleoenvironmental Of Ebinur Lake,Xinjiang And Its Driving Mechanis Of Climate Change

The development and evolution of Lakes with distinct regional characteristics were significantly influenced by the regional climatic and environmental conditions.The sedimentary features of lakes is unique and irreplaceable for the study of the global change and regional response.Located in the inland arid zone in Northwest China,the Ebinur Lake is the second largest saltwater lake in China,and its sedimentary features could probably record the climatic change in the inland arid and semi-arid region in Northwest China.On the basis of AMS14C dating,this study reconstructed the regional paleoclimate evolution processes from 2030 BP by analyzing several palaeo-climate proxies.The primary results and conclusions are summarized as below:1)The granularity frequency distribution of aeolian sediments in the Ebinur Lake follows the unimodal distribution,with sandy fraction accounting for the largest proportion of the aeolian sediments.Inconsistent with that of the aeolian sediments,the granularity frequency distribution of lacustrine sediments in the Ebinur Lake follows bimodal distribution with a large variation of sandy fraction.The content of environmental sensitive components varied consistently with the averaged grain size in the sedimentary profile,the strong change of content suggests the frequent sand-drift activity in the study region.The CIA value varied between 39.17～50.48,indicated that the sediments are in the primary weathering stage.2)The paleoclimate evolution processes in the Ebinur Lake region from 2030 BP were reconstructed by analyzing variation of geochemical elements and granularity with depth in sediment profile of the Ebinur Lake.In specific,the climate in the Ebinur Lake region was cold and arid during 2030～1980 BP(83.8～79.3 cm).The sand-drift activity was strengthened during the period.The climate tended to be wet during 1980～1930 BP(75.4～71.5 cm)with increased precipitation and enhanced chemical weathering.The climate was cold and arid during 1930～1880 BP(75.4～71.5 cm).The content of the environmental sensitive components peaked at approximately 72.5cm depth of sediment profile(1890 BP),indicated strengthened sand-drift activity.The climate tended to be wet during approximately 1880～1800 BP(71.5～66.0 cm)with weaker sand-drift activity.The climate of the Ebinur Lake region dried rapidly during 1800～1720 BP(66.0～59.5 cm).And the sand-drift activity was enhanced during this period.Whereas the sand-drift activity turned to be weak during 1720～1600 BP(59.5～50 cm).And the weather changed to be wet.The lake region was in the eolian sedimentation stage from 1600 BP to present with strengthened sand-drift activity.3)There is a good comparability of the paleoclimate records by the sediments in the Ebinur Lake,the ice core/tree rings records in the Tibetan Plateau and stalagmite record in the Mt.Tianshan.Intensity of the westerly and solar radiation could be the dominant factors driving the regional short-medium scale paleoclimate change.