冲绳海槽中段近4万年来沉积物属性和来源

对冲绳海槽中段DGKS9603孔134个样品(孔深0~481cm),测试了18种常、微量元素,对该柱样的29个样品(孔深0~488cm)进行了REE测试。对采自长江三角洲的CYm柱样和黄河三角洲的S3柱样中的晚更新统的5个样品进行了常、微量元素和REE测试。分析表明,冲绳海槽中段在全新世、末次盛冰期和末次间冰期的沉积物均以陆源物质为主,生物沉积为次。末次盛冰期以陆源硅质碎屑沉积的大量增加为特征;全新世生物沉积量有较大的增加;末次间冰期介于上述两者之间,但较全新世更富陆源物质。冲绳海槽的物源演化受末次冰期的影响,具有阶段性。对比冲绳海槽与长江和黄河物源的地球化学参数,包括REE、稀有元素、惰性常、微量元素,判识出末次盛冰期冲绳海槽的陆源物质,具有长江源的物质属性,沉积物可能主要来自古长江。

Property and Source of the Sediments in the Middle Okinawa Trough since the Last 40 ka

Evidence from sediments in cores was collected from Core DGKS9603 in the middle Okinawa Trough, Core CYm in the Changjiang River Delta and Core S3 in the Huanghe River Delta. One hundred and thirty four samples of Core DGKS9603 (depth 0 - 481 cm) were analyzed for 18 major and trace element compositions, and 29 samples (depth 0 - 488 cm) were analyzed for REE. Five samples of CYm and S3 cores from the upper Pleistocene were analyzed for their major, trace and rare earth elements. These analyses show that the sediments in the middle Okinawa Trough were predominated by terrigenous sediments and subordinated by biogenic sediments during the Holocene, the LGM and the last sub-interstadial epoch. During the LGM the terrigenous siliciclastic sediments had a great increase, while the biogenic sediments had a large increase during the Holocene, and the sediment characteristics during the last sub-interstadial epoch were between the LGM and the Holocene, but they were richer terrigenous sediments than in the Holocene. The evolution of provenance in the Okinawa Trough was influenced greatly by the last glaciation, and it is of staged characteristics. By comparing various geochemical parameters including REE, rare element, immobile major and trace elements in the Okinawa Trough, the Changjiang and Huanghe sediments, the author identifies that the terrigenous sediments in the Okinawa Trough during the LGM had the properties of the origin of the Changjiang material, the sediments in the Okinawa Trough had probably have derived from the Paleo-Changjiang River.