Microfossil Records and Shifts of Paleo-Kuroshio Current in the Nankai Trough since last 1 Ma

Abstract:

Kuroshio Current plays an important role in the oceanographic and climatic change in the West Pacific Ocean. Nearly few detailed record documented its long term variation history extending to middle Pleistocene period by previous studies. During Intergrated Ocean Drilling Exp. 315 in the Nankai Trough, a 100 m long sediment sequence in the upper part of Hole C0002D, which contains relative abundant calcareous fossils and with an age of Middle to late Pleistocene (1 Ma) was recovered.

Age constrain for the sequences was based mainly on calcareous nannofossil biostratigraphy in combine with a few of paleonmagnetic stratigraphcial data (Expedition 315 Scientists, 2009) and plankton foraminiferal data (G. ruber (pink). Date sets of U^K₃₇ and plankton foraminiferal oxygen isotope were analyzed to constrain records of glacial-interglacial cycles, surface paleo-temperature (SST) and paleon-salinity (SSS). Records of these microfossil proxies vary in response to glacial-interglacial changes during the last 1 Ma. These records indicate that this region had be dominated by paleo-Kuroshio Current during five periods (MIS17, MIS13, MIS7, MIS5 and MIS1). The possible influence of the Northen Pacific Center Water Mass was seen during MIS16 and MIS11.

Ref.: Expedition 315 Scientists, 2009. Expedition 315 Site C0002. In Kinoshita, M., Tobin, H., Ashi, J., Kimura, G., Lallemant, S., Screaton, E.J., Curewitz, D., Masago, H., Moe, K.T., and the Expedition 314/315/316 Scientists, Proc. IODP, 314/315/316: Washington, DC (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.314315316.124.2009