Magnetic investigation of surface sediments of the northwestern South China Sea: Implication for sediment provenance and transportation

Abstract Environmental magnetism has been widely used as a rapid, cost-effective, and non-destructive method in various fields including sediment source identification. Systemic magnetic measurements were performed for surface sediments collected from sixty-eight stations within the eastern Beibu Gulf to the south of the Hainan Island. The results indicate that a mixture of single domain (SD) and multi-domain (MD) or persuade single domain (PSD) magnetite and a small part of hematite controlled the magnetic properties of the studied sediments. From north to south, concentration of magnetic minerals slightly decreased and then increased. The study area is partitioned to three sedimentary zones from west to east. Terrigenous input materials from the Qinzhou bay, the Red river, and rivers in the Hainan Island are transported from zone I, II, to III. Terrigenous input dominated sediments of the northern and eastern BBG. Both north–south terrestrial materials and south-north marine sediments carried by offshore tidal current are mixed at further outward to the south of the Hainan Island. The present study proves the effectiveness of the magnetic method for examining provenance and transportation of sediments. We believe that sediments in the eastern Beibu Gulf to the south of the Hainan Island were transported from Qinzhou bay, Red river, and rivers in the Hainan Island.