Elemental geochemical characteristics of surface sediments from the southern Kyushu-Palau Ridge and their geological significance

The Philippine Sea, with its special geographical location, is rich in frontier geoscience issues and is a natural laboratory for studying the Earth multi-layer interactions. In recent years, the southern section of the Kyushu-Palau Ridge in the central Philippine Sea has become a hot spot for geoscience research, but its surface sediment provenance and sedimentary environment are not yet well understood. The sediment geochemistry of 69 stations collected from the southern section of the Kyushu-Palau Ridge at water depths of 3900-6100m was studied to identify the spatial variability of sediment provenance and depositional environments. The results show that the sediment types in the study area are pelagic clay and siliceous ooze, and the clastic components of sediment are less chemically weathered, less affected by sorting and recycling, and are mixed products of Asian dust materials and island-arc volcanic materials, of which Asian dust materials are dominated; and the different types of sediment in the study area are basically in an oxidative depositional environment, and the bottom water redox conditions are not a controlling factor for the enrichment of transition metal (e.g., Mo) elements in the sediments, indicating that Fe-Mn (oxyhydr)oxides are an important link between the source-sink processes of transition metal elements at the water-sediment interface. In addition, bottom redox conditions may not be necessary for the preservation of diatom mats.