Variation Of Coccolith Assemblages In Hole IODP C0002D From The Nankai Trough Since Last1Ma

A quantitative investigation and analysis of Mid-Pleistocene to Holocenecalcareous nannofossils of Hole C0002D of IODP Exp.315from the Nankai Troughwas carried out to evaluate the variation of the coccolith assemblages in response toclimatic changes since last1Ma. The oxygen and carbon isotope composition ofplanktonic foraminifera Globigerinoides ruber, and the contents of biogenic silica,and the other research, were be used to reconstructed paleo-sea surface salinity,pale-productivity, and the evolution of the paleo-Kuroshio Current during the last1million years.Twenty-seven species of calcareous nannofossils were identified in this core, andGephyrocapsa oceanic, Florisphaera profunda are the dominant species of thecoccolith assemblages. The warm-water species and the eurythermic species are themain components of the coccolith assemblages, the cold-water species had been themain components in the evolved history. The contents of the species of the coccolithassemblages correspond well with the glacial/interglacial cycles.The coccolith assemblages and the paleo-sea surface salinity show that themarine condition in the study area was quite complex. The upwelling, the PacificCentral Water Mass and the Subarctic Mass may be important to the area in additionto the Kuroshio Current.The impact of the Kuroshio Current mainly concentrated during the interglacialperiods, the study area was under the Kuroshio domain during the periods MIS17,MIS13, MIS6, MIS5b-3and Holocene. During MIS14-8, the Subarctic Mass mayarrived this area. The marine environment was controlled by the Pacific Central WaterMass ranther than the Kuroshio over the periods MIS16and MIS11. And the Coastalcurrent was the main factor during MIS19. The Kuroshio domain may not been in thethe study area during MIS10-9and MIS7.