Particle Size Analysis of Surface Sediments and Its Significance in Hexi Corridor of China
This paper systematically collected surface sediment samples,including Gobi,desert sand and river sediments in Hexi Corridor and Qilian Mountains. Based on the researches on the grain-size parameters,it obtains the following results:a)the grain size of fine-grained sediment generally superimposed by multiple-component composition,expressed as multi-component particle size distribution characteristics, indicating the nature of the transportation,power intensity,handling methods and so on are controlling factors;b)the grain-size parameters characteristics of desert sand,the Gobi surface sediment samples,the river floodplain surface sediment samples and surface sediment samples of Qilian Mountains are clearly different. Along the Qilian Mountains to the river (Shiyang River and Heihe River)to stable Gobi desert to the Gobi desert to the stabilized desert,the median particle size increases,sorting coefficient also increases and the skewness becomes to be negative gradually;c)Shiyang River and Heihe River would carry materials from Qilian Mountains to the washland,then the washland turns to be flood plain under the conditions of floods,these plain will form gobi desert and Tengger Desert and Badain Jaran Desert eventually with the aridification. Zonal distribution of washland,flood plain and desert are the results of wind differentiation on the piedmont alluvial materi-als. All these can be used as the dust source areas during the transmission,and these sub-regions are connected and inherited in the materi-al. Due to prevailing northwest wind or north wind in Hexi Corridor and the frequent dust storms,caused from the Qilian Mountains to wash-land to gobi desert to desert,the fine-grained material is transported gradually to the Chinese Loess Plateau and other areas,and thus the me-dian particle diameter and the average particle size gradually increase. d)Gobi,washland and deserts,including Tengger Desert and Badain Jaran Desert,in Northwestern China are the source areas of dust,mountain processes (including glacial grinding,frost weathering,foreland fluvial and so on)in northwestern China have played an important role in producing the vast amounts of dust.
国家科技期刊平台
NSTL
万方数据
维普
