毛乌素沙地15ka以来气候变化及沙漠演化研究

Climate Changes and Desert Evolution of Mu Us Desert since 15 ka BP

通过对毛乌素沙地东南缘的三道沟剖面进行沉积学分析,结合常规14C和光释光测年结果,并与已有研究进行对比,将毛乌素沙地15ka以来的演化过程分为4个阶段:15ka以前,处于末次冰期极盛期的后期,冬季风活动强烈,气候干冷、风蚀强烈,沙漠处于活化扩张阶段;15～6.33kaBP,气候逐渐回暖,风力减弱,但沙丘仍处于活化状态,期间可能有气候的暖湿波动;6.33～3.5kaBP,夏季风活动较强,冬季风活动较弱,气候总体温暖湿润,沙丘固定、沙漠退缩,其中又存在一些干冷波动,5kaBP前后气候曾发生突变;3.5kaBP以来,冬季风活动又逐渐增强,夏季风活动减弱,气候寒冷干燥,风沙活动增强。

The transitional area between Mu Us Desert and Loess Plateau is typically sensitive to global changes,so this area is ideal for research of climate change and desert evolution.Through analysis on sediments in Sandaogou section that located on desert-loess transitional area,in combination with 14C dating and optically stimulated luminescence dating and the former researches,the characteristics of climate change and desert evolution in Mu Us Desert since15 ka BP are discussed：（1）Before 15 ka BP,Mu Us Desert experienced the late Last Glacial Maximum,the climate there was dry and cold,the winter monsoon was stronger and the deserts expanded.（2）15～6.33 ka BP,the climate was warmer and wind was weaker than before,but sand dunes were moving types.There were some warm-wet events during this period.（3）6.33～3.5 ka BP,winter monsoon was weaker and summer monsoon was stronger than before.The climate was warm and wet,and the deserts area contracted.But there also had some fluctuations of dry-cold climate,especially the cooling event occurred in about 5 ka BP,which was clearly recorded in Mu Us Desert.（4）Since 3.5 ka BP,the winter monsoon became stronger again and the summer monsoon was weaker,the climate was dry and cold,and aeolian activities became stronger.