Contrasting spatial distributions of surface sediment compositions from the Emperor Seamount Chain, North Pacific

The Emperor Seamount chain is located in the North Pacific Ocean and beneath the Northern Westerly wind belt. It extends from the subtropical to subarctic North Pacific oceans between 30°N-50°N. Modern observations have shown this region has complex physical oceanic processes, including the Kuroshio Extension, the Oyashio Current, the polar front and the subarctic front. A large amount of dust from the central Asian continent is delivered to this area, which affects the regional marine ecosystem and the global carbon cycle. Due to the lack of sediments from the Emperor Seamount chain, few studies have examined the composition of surface sediments in this ocean realm. On the basis of 50 samples collected during the SO264 Expedition in 2018 using multicorers, we investigate the spatial distributions of sediment grainsize, total organic carbon, CaCO₃ and major and minor elements in surface sediments of this ocean realm. Our data show that the detritus sediments mainly consist of siltly sand and clayey silt with more coarse fractions between ~45°N and 48°N, which has strong negative correlations with water depth. The content of CaCO₃ varies between 0.04% and 83.67% with higher values at the south of 48°N. The TOC content ranges between 0.07% and 1.36% with lower values (<0.3%) occurring at the north of ~45°N. The concentration of ∑REEs ranges from 31 ppm to 136 ppm with lower values between ~45° N and 48°N. There is significant positive Eu anomaly at all stations, indicating widespread occurrence of volcanic detritus. A significant negative correlation between sediment grainsize and ∑REEs and some lithophile elements, such as Al₂O₃, Fe₂O₃, K₂O, Th, REEs, etc., indicates a strong effect of sediment grainsize on sediment geochemical composition. A strong negative correlation between Al and CaCO₃ suggests contrasting sources, such as terrigenous vs biogenic sources, respectively. Our data confirms the contributions of terrigenous, volcanic and biogenic materials to the bulk sediment with contrasting spatial distribution along the Emperor Seamount Chain.

Note: This study was supported by the National Natural Science Foundation of China (Grant No.41876065, U1606401) and National Program on Global Change and Air-Sea Interaction(GASI-GEOGE-04).