XRF, carbon and nitrogen organic and isotopic geochemistry, clay mineral and grain size data from sediment core MD18-3532, eastern Taiwan, over the past 26 kyr

The Kuroshio Current flows northward along the east coast of Taiwan toward the Okinawa Through and the East China Sea, but its dynamics and trajectory were probably different during the Last Glacial Maximum (LGM) due to the globally lower sea level that could have caused a (debated) deflection of the current along the eastern edge of the Ryukyu Arc. Core MD18-3532 has been recovered in an intra-slope basin of the Ryukyu accretionary prism, currently disconnected from the Kuroshio Current, but which could have been under its trajectory in case of a NE deflection. Measurements of clay mineral assemblages and illite crystallinity revealed that Taiwan has been the main sediment source at this site over the last 26 kyr. The significantly higher sedimentation rate between the glacial period and the Bølling–Allerød compared to the Younger Dryas and Holocene, coupled with very low δ15Nsed during the LGM and Heinrich Stadial 1, provide evidence for a deflection of the main branch of the Kuroshio Current toward the eastern edge of the Ryukyu Arc during those periods. The deflected current carried surface sediment plumes and Trichodesmium spp. cyanobacteria to the coring site. δ13Corg, TOC, TN, and XRF analyses indeed revealed increased marine primary productivity during the LGM and Heinrich Stadial 1, likely due to intensified East Asian Winter monsoon winds leading to increased nutrient input from dust and the upwelling of nutrient-rich subsurface water from the deflected Kuroshio Current through the deepening of the mixed layer.