Eolian Activity and Environment Evolution History Recorded by the Qingtu Lake,NW Tengger Desert

Lacustrine sediment samples from QTL01 section of Qingtu lake in NW Tengger Desert,pretreated by removing the organic matter and carbonate,are measured by Malvern 2000.Standard deviations are calculated for samples from the depth of 214～560cm of QTL01 section,and grain size components sensitive to environment are obtained.The result from our study suggests that the content of 60～550 m component is sensitive to local eolian activity and the content variation of 60 m component indicates the changes of river discharges drained into the lake.Based on the grain size analysis and 14C dating,we reconstructed the variations of eolian activity and environment of the studied area during 10～2.5Cal kaBP:From 10 to 7.8Cal kaBP,gradually decreasing eolian activity indicated the area was becoming humid during the early Holocene;From 7.8 to 7.5Cal kaBP,very intense eolian activity suggested a regional dry event;From 7.5 to 5Cal kaBP,weak eolian activity indicated a very humid environment;From 5 to 2.5 Cal kaBP,the gradually weaker eolian activity showed a trend toward aridity in the study area.