Formation mechanisms of fluvial residues from eastern watersheds of China: Insights from corrected weathering process and sediment provenance

Abstract

Investigating the weathering process and provenance of fluvial residues plays a crucial role in revealing superficial circulation on earth. Although the transfer and inheritance processes have been well elaborated for intra-watersheds, the limitations and applications of geochemical proxies need to be further explored for cross-watersheds. Geochemical analysis was performed on 541 surficial sediment samples from 12 intertidal zones in China, combined with traditional weathering indices, mass transfer coefficients, and rare earth element parameters, to gain a better understanding of their geochemical behavior. Based on the interactions of lithology, hydrodynamic sorting, and sedimentary recycling on various weathering indices, the metamorphic and succession processes of the residues were fully characterized during the source-to-sink process. The weathering index of Parker (3.9–66.2) was more susceptible to the hydrodynamic sorting effect, whereas the chemical index of alteration (45.8–83.9) was heavily influenced by the sedimentary recycling process. In comparison, the mass transfer coefficient of Na provides better performance in the early weathering stage and is optimally protected from the effects of hydrodynamic sorting and sedimentary recycling. As confirmed by the corrected mass transfer coefficients and weathering indices, regional temperature and precipitation co-dominated the weathering heterogeneity. Parameters excluding heavy rare earth elements were hardly affected by the weathering process and grain-size effect, and were the most sensitive geochemical proxies for tracing the provenance of fluvial residues. This could provide a scientific basis for cross-watershed research, source apportionment, and regional geological background.