Source-to-sink processes of fluvial sediments in the northern South China Sea: Constraints from river sediments in the coastal region of South China

Abstract

The fine-grained fractions (<63 μm) of nine fluvial sediments from South China coastal rivers (SCCR) and fourteen surface sediments from the continental shelf of the northern South China Sea (NSCS) are analyzed to determine the major and trace elements and Sr-Nd isotope compositions and differentiate the sediment sources and factors that control the distribution of geochemical compositions on the NSCS shelf. The results reveal that the geochemical compositions of sediments from the SCCR differ from each other and can be utilized to identify the sediment provenance in the study area. These river sediments are mostly deposited on the continental shelf of the NSCS, and their influence is different in various locations. Sediments on the eastern and western sides of the Pearl River mouth have different εNd values and 87Sr/86Sr ratios, indicating that the weathering intensity varies greatly from the eastern side to the western side. The main sediment sources in the NSCS shelf contain fluvial sediments discharged by the eastern and western coastal rivers of South China and the coastal rivers of western Taiwan and relict sediments on the continental shelf.