Tracing sediment provenance in the Yellow River, China: Insights from weathering, recycling, and rock compositions

Abstract

Geochemical investigations of fluvial sediment help understand the provenance of sediment and surface processes taking place on the Earth at the watershed scale. This study is aimed at identifying the weathering and sedimentary recycling of the surface sediment of the Yellow River using the Chemical Index of Alteration (CIA), Weathering Index of Parker (WIP), Index of Compositional Variability (ICV), Mafic-Felsic-Weathering (MFW) ternary diagram, and Al-Ti-Zr ternary diagram. Source rocks compositions were clarified using Al2O3-CaO⁎+Na2O-K2O (A-CN-K), MFW, discriminant function, and Cr/V vs Y/Ni diagrams. The results demonstrated that the surface sediment of the Yellow River has experienced an overall low intensity of weathering and recycling. However, significant differences were observed in the characteristics of weathering and recycling among the upper, middle, and lower reaches, which is in turn associated with the differences in climatic conditions and tectonic settings. Source rocks manifested a typically mixed type composition, including felsic igneous rocks, intermediate igneous rocks, quartzose sedimentary rocks, and mafic components. Moreover, the sediment in the source area of the Yellow River may have originated from the clastics produced by the abrading of mountain glaciers. Sediment in the area in which the Yellow River flows through the Chinese Loess Plateau primarily originates from loess in the desert in Northwestern China. Sediment in the lower reaches does not only include the sorted sediment flowing down from the upper and middle reaches, but also that imported from regional rivers. This study can furnish a sound scientific basis for the reconstruction of the paleoclimatic and paleoenvironmental changes that affected large watersheds in arid and semi-arid areas.