DISTRIBUTION OF MICROGASTROPODS IN OKINAWA TROUGH SURFACE LAYER SEDIMENTS AND THEIR SIGNIFICANCE
Feng Weimin, Huang Baoyu(Nangjing Institute of Geology and Palaeontology, Chinese Acadmy of Sciences,Nanjing 210008)
Microgastropods in the surface sediments of the northwest side of the Okinawa Trough, are characterized by mixed ecological features indicating their inconsistency with the modern oceanic environment there. The microgastropods,except for a minority of species representing deep sea background,mainly consist of representives of inner shelf or offshore shallow water. Therefore, this fauna obviously show the ocean environments of low sea-level during the last glacial epoch of Late Pleistocene,while a minority of deep sea species in this fauna may relate to upwelling formed by the Kuroshio in the northern edges of the Okinawa. Trough. Based on the microgastropod distribution in other sea areas,it can be inferred that Kuroshio during the late glacial epoch of Late Pleistocene still exerted an important influence over the microgastropod distribution in this region,and that sea-level rise during the Holocene led to the present mixed ecological aspects of microgastropod fauna.