The Study On Climate Change Of Muli Aera In The South Of Qilian Mountains Over The Late Quaternary

This paper selected the quaternary stratigraphic in Muli aera as research object, which is in the south slop of Qilian Mountains. Based on the precise measurement of 14 C ages and optical stimulated luminescence ages, and combining with the study of some environmental proxies such as grain size, magnetic susceptibility, oxide（SiO₂、AL₂O₃、Fe₂O₃） content, and normal paraffin. we reconstruct the climatic change of the study area over the late Quaternary, and also compared with global climate change, the main conclusions are as follows:（1）The stratigraphic of the Late Quaternary in Muli area can be divided to 3 units, they are stratigraphic of Late Middle Pleistocene- Early Late Pleistocene（the last interglacial）,stratigraphic of the Late Stage of Late Pleistocene（last glacial） and stratigraphic of Holocene. The stratigraphic of the last interglacial: outwash sediments, gray green, gray or dark red gravel layer. The stratigraphic of last glacial: black or gray gravel layer,black clay layer, brown or grayish clay layer containing gravel. The stratigraphic of Holocene : dark grey or gray clay layer, dark gray or grayish yellow silt laye.（2）The climate change in Muli region over the late Quaternary can be divided into three stages: Ⅰ:144-75 KaBP,the overall climate of this stage is warm and humid, but there is a tendency to turn cold in the late. Ⅱ:75⁹KaBP,all the proxies show that the regional environment is dry and cold, corresponding to the last glacial period.Ⅲ:This phase is warmer than the previous one, corresponding to the Holocene warm period.（3）The climatic change during the Late Stage of Late Pleistocene（ 44.8³5kaB.P） at Muli area in the South of Qilian Mountains can be devided into 3 parts: Ⅰ.44.8⁴0.5kaB.P., all the proxies show that the regional environment is warm and humid. The warm event around 40.97 ka B.P. corresponds to IS12 in Dansgaard-Oeschger events;Ⅱ.40.5³5.5kaB.P., the climate fluctuated frequently and tended to be cold. IS9^IS11 warm events, 35.8 ka B.P., 37.5 ka B.P., 39.7 ka B.P., and H3 cold event, 35.5 ka B.P., were captured during this period; Ⅲ.35.5³5 kaB.P., the climate fluctuated strongly and tended to get warm. These features of climatic fluctuation fit well with those of the late stage of MIS3.（4） Based on analysis of the normal paraffin’s distribution characteristics, and comparing with the other environmental substitute index, it can be seen that the lipid molecular fossils can be used to analysis environment change, and is an effective method in the research and climate change.