Elemental Compositions of Surface Deposits in Hexi Corridor and Its Adjacent Areas, Northwestern China

Elemental compositions of surface deposits, collected from the gobi (rock desert), river plain (alluvium of Shiyang River and Heihe River), desert (Tengger and Badain Jaran) and northern piedmont of Qilian Mountains in the Hexi Corridor and its adjacent areas, were analyzed. Meanwhile, elemental composition between the Luochuan loess and the different types of surface sediments in the study region were also compared. The results showed that geochemical features of incompact deposits among different types of surface in the researched area, which may come from the altiplanation of Qilian Mountains, are aligned fairly well. Namely, it was the process of material transportaion from Qilian Mountains to sediment coccyx that caused the provenance consistency in the study area. The distribution patterns of trace element and feature element in the Hexi Corridor and its adjacent areas are in good agreement with that of Luochuan loess, implying that gobi, river plain (alluvial fan) and desert in the study area are likely to be the dust sources of loess deposits on the Loess Plateau. In the course of moving from Qilian Mountains to the Hexi Corridor, detrital particles are enriched with coarse-grained components, due to a certain degree of sorting by hydrological and windy agents. As a result, weathering indices of surface deposits in the Hexi Corridor are lower than that in the piedmont of Qilian Mountains. Because of the stronger wind erosion in Tengger and Badain Jaran desert, the median particle diameter of dune sand there is the coarsest, which results in the lowest indices of chemical weathering.