从沉积重矿物与土壤养分特点看毛乌素沙地全新世环境变迁

THE CHARACTERISTICS OF HEAVT MINERAL,OPGANIC MATTER,TOTAL NITROGEN AND PHOSPHORUS CONTENTS IN HOLOCENE DEPOSITS AND THEIR CLIMATIC SIGNIFICANCE IN MU US SAND SEA

根据全新世沉积重矿物组合与古土壤养分分析的结果，认为毛乌素沙地全新世沉积环境有过多次正逆变化：１１－１０ｋａＢ。Ｐ．、８５００－５０００ａＢ，Ｐ．、４０００－３５００ａＢ．Ｐ．、２７００－２０００ａＢ，Ｐ．以及１５００－１０００ａＢ．Ｐ．时期气候较为潮湿，土壤、植被发育较好，化学风化作用较强，风沙活动受到限制，为相对低能的沉积环境。介于其间的时期则分别为机械风化作用占优势的高能沉积环境，土壤风蚀严重，气候较为干燥。

Based on analysing the contents and characteristics of sedimentary heavy mineral,organic matter,total nitrogen and phosphorus in Holoce ne de posits,this paper deals with theenvironmental changes of Mu Us Sand Sea, which lies in the temperate and semi-arid steppe zone.The results show that the climate was relatively humid ,soil and vegetation cover were better and themobilities of sand dunes were limited during the peried of 11-10 ka B.P.,8 500-5000 a B.P.4000-3500 a B.P.,2 700-2000 a B.P. and 1 500-1000 a B.P. respectively. While themechanical weathering was dominent:wind sand activities were frequent;vegetation was sparse,soil ercoion was serious and the climate was dry during the interval periods mentioned above.