Abstract:
Late Quaternary hemipelagic sediments of the Japan Sea are characterized by cm to m scale rhythmical repetition of the dark and light layers. High-resolution analysis of sediment core from ODP Site 797 of south central Japan Sea revealed that these dark and light layers reflect millennial-scale paleoceanographic changes within the sea which are associated with large and abrupt climatic changes known as Dansgaard-Oeschger Cycles (DOC) which have recently been confirmed by analyses of ice cores from central Greenland. The dark layers depositions, which correspond to interstadials of the DOC, reflect increases in the relative contribution of East China Sea Coastal Water to the influx to the Japan Sea, consequent decreases in the surface water salinity and reduction in deepwater production, and the increase in surface water productivity, whereas light layer depositions, which correspond to stadials of the DOC, reflect decreases in the relative contribution of East China Sea Coastal Water, consequent increases in surface water salinity and enhancement of deepwater production, and decreases surface water productivity. In addition, variation in the relative contribution of the East China Sea Coastal Water could have been caused by changes in the discharge from the Huanghe and Changjiang Rivers which should have reflected wet and dry cycles in Central Asia.