萨拉乌苏河地区地层中的碎屑矿物及其所反映的中更新世末期以来之气候环境变化

The Change in Climatic Environment of the Salawusu River Area Since the TerrninaJ Stage of Mid-Pleistocene As Indicated by Detrital Minerals in Quaternary Sediments

文章根据对萨拉乌苏河地区第四纪地层中的碎屑矿物分析结果,将重矿物按其抗化学风化的能力不同分为不稳定、较稳定、稳定和极稳定四种类型,不同层位的重矿物类型的百分含量不同,从而可求出重矿物的风化系数HW。不同时期地层的HW不同,而HW的大小变化与化学风化的程度有很大关系,一般来说,化学风化作用强,HW相应变小。而化学风化作用的强弱又主要受气候的影响,从而可推测该时期气候环境的变化。

Based on analyses of detrital minerals from the Quaternary sediments in the Salawusu River area, the authors discuss the change in climatic environment of that area since the last stage of the Middle Pleistocene. It is pointed out thai(1) during the development of loessial palaeosoil and the deposition of aeolian sand, the climatic environments were warm-humid and dry-cold respectively; (2)the fluviolacustrine facies of Salawusu formation and the aeolian sand of Chengchun Formation of the late Pleistocene are products of warm-humid and dry-cold climatic conditions respectively, in which the lake-swamp facies of Middle Chengchun Formation was formed under cool and humid climatic condition, and(3)during the deposition of the lake swamp facies of Dagouwan Formation and the fluviolacustrine facies,black soil and secondary loess of Dishaogouwan Formation(all belonging to Holccene period), the climate was relatively warm-humid,and during the deposition of medern Maowusu sandy desert,the climate turned dry-cold again.