Sediment provenance on the northwestern shelf of South China Sea and the sedimentary model for heavy-mineral placers

In the northern South China Sea (SCS), a series of surveys of marine resources since 1950s have found several heavy mineral placers on the northwest shelf (Tan and Sun, 1988; Zhang et al., 1992). Previous studied have not clearly identified the sediment sources of shelf sediment in the northwestern SCS. The purpose of this study is to analyze the provenance of shelf sediments in the northwestern SCS by using bulk geochemistry and single-mineral chemistry and to explain the occurrence of heavy mineral placers on the shelf. The main results obtained are as follows (Li et al., 2015, 2016): 1) No evidences from bulk geochemistry and mineral chemistry show shelf sediments on the western shelf of northwestern SCS (west of the Xiachuan island) are mainly sourced from the Pearl River. 2) The Jian River is the most important supplier of sediments on the western shelf. 3) Heavy mineral placers sourced from the Pearl River match with placers of "big river model", mainly distributed in deep waters on the northwestern SCS shelf(Fig.1). 4) Heavy mineral placers sourced from other rivers match with placers of "small river model", mainly distributed in shallow waters on the northwestern SCS.