Mineral composition and geochemical characteristics of sinking particles in the Challenger Deep, Mariana Trench: Implications for provenance and sedimentary environment

Abstract The properties of sinking particles in the ocean can reflect geochemical cycles of marine organisms and are related to oceanic mineralization. In this paper, sinking particles were collected with time-series sediment traps at three depths (2000 m, 4000 m and 6000 m) in the Challenger Deep in the Mariana Trench. The mineral compositions and geochemical characteristics of the sinking particles were analyzed in order to determine their provenance and the redox depositional environment of the surrounding seawater. The results reveal a total of 7 categories and 24 kinds of minerals (compounds) in the sinking particles, which are sourced mainly from volcanic materials eroded from surrounding ridges and oceanic basins, among which the West Mariana Ridge and Kyushu-Palau Ridge contribute the most. Terrestrial eolian dust and oceanic authigenic minerals contribute little. The particle flux is higher at 6000 m than at 2000 m and 4000 m, and the supply rates are higher in spring. Analytical results for DO data, redox-sensitive elements (Th/U and V/Sc) and rare earth elements show that there is an oxidative sedimentary environment and that the oxidation degree of seawater increases with the depth, which is affected by the oxidized bottom water. No systematic variation in depositional environment was observed in spring and in summer.