A study on Transporting process of clastics under Kuroshio Extension.

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It is revealed that the rock-magnetic property of surface sediment under Kuroshio Extension is characterized by magnetite in magnetic mineralogy, and the high distribution in amount of magnetic mineral is recognized at 32-34゜N. In the condition which magnetic mineralogy is dominant in magnetite, the large magnetic grain size at 34-32゜N is observed, but the distal and southern sites involve the smaller magnetite. These spatial distributions of the grain size and amount of magnetite suggest that the clastic material of Izu-Ogasawara ridge, which including magnetic mineral, is spilled by the stream of Kuroshio Extension into the Northwest Pacific basin.The spatial and temporal distribution of the sediment character in the study area show the distinction in the chemical and rock-magnetic property between glacial and interglacial periods. At the maxima in glacial period, the magnetite contribution to the sediment component is small, the bulk chemical component shows less in Al and rich n Si. These patterns suggest the small supply of clastics, probably because the stream pattern of Kuroshio Extension was different from the current situation. In the interglacial glacial periods, 34゜N core shows the smaller change in grain size, on the other side, cores in southern and proximal sites shows that the grain size have changes unsteadily. The interpretation of the changes is that 34゜N core have been in axial zone of the Kuroshio Extension in constant, but the others have been in the margin of the Kuroshio Extension, and been susceptive to the change of Kuroshio Extension.The change of amount of magnetic mineral shows a high fluctuated pattern, and this pattern is very similar to the isotope data of the Greenland Ice-core.