Environmental changes recorded by lake sediments from Lake Jili,Xinjiang during the past 2500 years

An 80-cm-long sedimentary core from Lake Jili,which lies in westerly area of China,provided detailed information about paleoclimatic and paleoenvironmental changes in the past 2500 years.The temporal sequence of sedimentary core was constructed using the ~(210)Pb,~(137)Cs and AMS ~(14)C dating methods on the bulk organic matter.Based on analyses of grain-size,total organic carbon,total nitrogen and organic carbon isotope,climatic and environmental evolution history in the past 2500 years was reconstructed. The sequence of climatic changes in the region since 2.5ka BP was established.The climatic changes experienced five stages:warm-wet climate during 500BC-50BC;cold-wet climate during 50BC-650AD;warm-dry climate during 650-1350AD warm period(MWP);cold-dry climate period during 1350-1850AD(LIA),and moderate-dry since 1850AD,including climate warming after 1920s,especially since 1970s.The records of climatic and environmental evolution of Lake Jili were in good according with the historical literature records and other geologic records of adjacent areas.