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下透光带钙质超微化石Florisphaeraprofunda的相对丰度 ,为揭示混合层厚度等海水上层结构的变化提供了新的可能 .冲绳海槽南北 3个站位近两万年来的沉积分析一致表明 ,F .profunda的百分比从冰期到全新世显著增高 ,海槽南部在距今约 4ka前再次一度减低 ,其变化与热带深层水种浮游有孔虫Pulleniatinaobliquiloculata的趋势一致 ,反映冰期时黑潮东移 ,海水混合层减薄 ,温跃层变浅 ,同时海水上层的浊度可能增大 .距今 4ka前黑潮可能再度东移 .
The relative abundance of Florisphaera profofunda in the lower translucent zone provides new possibilities for revealing the superstructure of the sea water such as the thickness of the mixed layer.The sedimentary analysis of three stations north and south of the Okinawa Trough shows that, The percentage of F. profunda increased significantly from the Ice Age to the Holocene. The southern part of the trough decreased once again about 4 ka ago. The trend is consistent with that of the tropical planktonic foraminiferal Pulleniatina obliquiloculata, reflecting the eastward movement of Kuroshio in the glacial period. Sea water mixture thinning, the thermocline shallow, while the turbidity of the upper sea water may be increased .About 4ka before the Kuroshio may eastward again.