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Changes in Kuroshio Current dynamics and East Asian monsoon variability during the last 26 kyr
Journal
Palaeogeography, Palaeoclimatology, Palaeoecology
Journal Volume
632
Date Issued
2023-12-15
Author(s)
Fenies, Pierrick
Bassetti, Maria Angela
Vazquez Riveiros, Natalia
Menniti, Christophe
Frigola, Clément
Babonneau, Nathalie
Ratzov, Gueorgui
Hsu, Shu Kun
Abstract
The Kuroshio Current flows northward along the east coast of Taiwan toward the Okinawa Trough 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 would have been on 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 from the Last Glacial Maximum to the Bølling–Allerød compared with the period from the Younger Dryas to the Holocene, coupled with very low δ15Nsed during LGM and Heinrich Stadial 1, provide evidence for the transport of sediments and Trichodesmium spp. cyanobacteria by the partially deflected Kuroshio Current toward the eastern edge of the Ryukyu Arc. Combined with δ13Corg, TOC, TN, and XRF analyses, an increase in primary productivity has been observed during LGM and Heinrich Stadial 1. This would have been caused by an enhanced East Asian Winter monsoon winds resulting in the deepening of the mixed layer that would have led to the upwelling of the Kuroshio Current nutrient-enriched subsurface waters to the oligotrophic surface waters, and the supply of dust-borne iron from the Chinese Loess Plateau.
Subjects
Kuroshio current deflection | Last deglaciation | NW Philippine Sea | Primary productivity | Taiwan paleoceanography | Trichodesmium spp.
Type
journal article