末次冰期以来松嫩盆地东部榆树黄土堆积及其环境意义

通过对松嫩盆地东部末次冰期以来榆树黄土剖面的粒度、磁化率等指标分析研究后认为:(1)该地区的黄土至少于4万年前的末次冰期开始沉积,沉积物类型为黄土与河流沙混合沉积,粒度可有4个组分,其中46kaB.P.以前主要是以第④组分为主导的水成河流沙,46kaB.P.以后主要以第③组分为主的黄土粉尘。(2)松嫩盆地东部的黄土粉尘主要来源于科尔沁、松嫩等西北广大沙地,末次冰期是科尔沁等沙地大规模发育的时期。(3)东北地区全新世气候演化可分成5个阶段:10000aB.P.左右,9000aB.P.左右,6000aB.P.前后,4500aB.P.左右,2500aB.P.以后。

The Yushu loess deposition in eastern Songnen Basin since the last glacial period and its environmental significance

Magnetic susceptibility and grain-size distribution of the loess-river sand profile in eastern Songnen plain of northeastern China since the last glacial period were analyzed,and the paleo-environmental history of this region was investigated.The results demonstrate that:1) the loess deposition of eastern Songnen plain occurred at least 46 ka B.P.,i.e.,at the last glacial period.There exist four modes of grain size distribution of sediments,which have been mixed with loess and river sand.The mode of river s...