Composition, origin and weathering process of surface sediment in Kumtagh Desert, Northwest China

• Published in: Journal of geographical sciences Vol. 21; no. 6; pp. 1062 - 1076
• Main Authors: Xu, Zhiwei, Lu, Huayu, Zhao, Cunfa, Wang, Xianyan, Su, Zhizhu, Wang, Zhenting, Liu, Hongyi, Wang, Lixin, Lu, Qi
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science Press 01.12.2011; Springer Nature B.V; School of Geographic and Oceanographic Sciences, the MOE Key Laboratory of Coast and Island Development, Nanjing University, Nanjing 210093, China%Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China%College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China%Lanzhou Institute of Arid Meteorology, China Meteorological Administration, Lanzhou 730020, China
• Subjects: Alluvial deposits; Arid zones; Asia; Bgi / Prodig; China; Continental crust; Correlation coefficient; Deserts; Earth and Environmental Science; Geochemistry; Geographical Information Systems/Cartography; Geography; Lake sediments; Minerals; Mountains; Nature Conservation; Physical Geography; Remote Sensing/Photogrammetry; Sediment samplers; Sediments; Weathering; 中国西北地区; 地球化学元素; 塔克拉玛干沙漠; 库姆塔格沙漠; 矿物成分; 组成相; 表层沉积物; 风化过程; North-Western China; China; geochemical elements; minerals; weathering process; Kumtagh Desert; sediment provenance; Sedimentology; Surface deposits; Mineralogy; Arid area; Geochemistry; Weathering; Heavy minerals; Desert; geochemical dements
• ISSN: 1009-637X; 1861-9568
• DOI: 10.1007/s11442-011-0900-3

Kumtagh Desert is one of the eight biggest deserts in China, but poorly investigated before our interdisciplinary study because of the difficulty of access. In this paper, 33 representative surface sediment samples were collected from the Kumtagh Desert and analyzed in the laboratory to obtain heavy mineral components and geochemical element contents. Results show that various kinds of heavy minerals are present in these samples, with high levels of epidote and hornblende. Si and AI take up a large part of chemical composition. Compared with the average composition of geochemical elements of the upper continental crust （UCC）, except Si and Ca, all elements are depleted to a certain degree; Fe, Mg, Ca, P, Ti and Mn have high correlation coefficients in their contents. The mineral and geochemical composition of the Kumtagh Desert sediments have a similarity with that of rocks of Altyn Tagh Mountains, and the surface sediments of the alluvial/diluvial fans around the Altyn Tagh Mountains and that of the Taklamakan Desert, indicating that one major source of the Kumtagh Desert sediments is located in the Altyn Tagh Mountains. Alluvial deposits and lake sediments in Aqik valley and lower reaches of Shule River are prone to be eroded and transported by the strong northeasterly wind into the Kumtagh Desert, forming another source of the desert deposits. An A-CN-K ternary diagram shows that a weak degree chemical weathering by the loss of Na and K occurred in these sediments, whereas A-CNK-FM ternary diagram suggests that Fe and Mg have undergone a significant chemical differentiation. Physical weathering processes cause easy erosion and enrichment in fine particles for mafic minerals, thus coarse desert sand particles can be relatively depleted in Fe and Mg. The mineral and geochemical composition of sediments in arid regions experiencing less chemical weathering are mostly affected by physical weathering.