冲绳海槽西北侧表层沉积物中微型腹足类的分布及其研究意义

DISTRIBUTION OF MICROGASTROPODS IN OKINAWA TROUGH SURFACE LAYER SEDIMENTS AND THEIR SIGNIFICANCE

冲绳海槽西北侧大陆架向大陆坡转折处表层沉积物中微型腹足类动物群具有混合的生态特征,这与现代海洋沉积环境并不一致。腹足类动物群中除少数种类为陆坡深海分子,多数种类属内陆架区或近岸浅水分子。因此,动物群主要反映了晚更新世末次冰期低海平面的海洋环境,而少数深海种类的混人应与黑潮暖流在冲绳北端所形成的上升流有关。根据本区腹足类在其他海区的时空分布规律,本文认为在更新世末次冰期,黑潮暖流仍对本区有重要影响,并控制着腹足类的分布。本区腹足类这种混合的生态特征是晚更新世末次冰期以来各种海洋动力环境叠加影响的结果。

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.