Reconstruction of Kuroshio intrusion into the South China Sea over the last 40 kyr

The Kuroshio current transports large amounts of heat and water vapor into the South China Sea (SCS) through the Luzon Strait and plays a key role in modulating the surrounding hydroclimate. However, there is no detailed high-resolution history of the Kuroshio intrusion into the SCS preceding the Holocene. Here, clay mineral assemblages and Sr–Nd isotopic values (87Sr/86Sr and εNd) of core CS11 represent the relative abundance of Taiwan and Luzon fluvial sediment contributions in the SCS deep basin, which can be further used as proxies of relative variation of the Kuroshio intrusion into the SCS over the past 40 kyr. Combined with linear sedimentation rate (LSR) and results of previous studies, we demonstrate that variations of Kuroshio currents between the SCS and the open Pacific display opposing trends within each marine isotope stage, similar to the waxing and waning of its modern configuration. The El Niño–Southern Oscillation (ENSO) has acted as the key factor driving variations of the Kuroshio currents over the past 40 kyr. During late marine isotope stage (MIS) 3, the Kuroshio intrusion into the SCS gradually decreased due to decline in intensity of El Niño-like conditions, while an El Niño-like state favored the Kuroshio intrusion into the SCS during MIS 2, in particular during the Last Glacial Maximum (LGM) when Kuroshio transport in the open Pacific weakened. The Kuroshio intrusion into the SCS was largely sluggish in the early Holocene, when a La Niña-like condition prevailed, and then the Kuroshio intrusion was enhanced during the middle to late Holocene under the influence of increased El Niño frequency.