Characterization of geochemical elements in surface sediments from Chinese deserts

Abstract

Northern China has 12 main deserts that range from extremely arid regions in the west to semi-arid or semi-humid regions in the east. Based on their geographical locations, we divided these deserts into western, central, and eastern deserts. We investigated the geochemical elements in their surface sediments and found that the concentration of the major element SiO2 gradually increased from west to east, whereas the other major elements tended to decrease; however, the CaO concentration was unusually high in the Taklimakan and Qaidam Basin deserts. The spatial distribution of geochemical elements was more homogeneous in the western and central deserts than in the eastern. Unlike the eastern deserts, the western and central deserts show greater physical than chemical weathering and lower mineral maturity due to the extremely low precipitation and a continuous supply of younger materials. Most major trace elements in the eastern deserts were more depleted relative to the upper continental crust than in the western deserts, but were moderately depleted in the central deserts. The potential source rocks of central and western deserts are composed of intermediate igneous source rocks, while the sediments in eastern deserts are derived from the mixing of felsic and intermediate igneous source rocks or the mixing of quartzose deposits and intermediate igneous source rocks. The spatial distribution of geochemical elements showed similar provenances of aeolian material in the Taklimakan Desert and Kumtag Desert, and similar provenances of aeolian material in the Badain Jaran, Tengger, Ulan Buh, and Hobq deserts. There were no obvious provenance relationships for the Otindag, Horqin, and Hulun Buir sandy lands in the central and western deserts.