冲绳海槽有孔虫壳体的微量元素Sr,Nd同位素地球化学
Trace elemental and Sr-Nd isotopic geochemistry of foraminifera shell of the Okinawa Trough
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摘要: 钙质生物壳的微量元素组合和Sr,Nd同位素组成是识别海底混合源沉积物中生物源物质相对贡献的重要参数.冲绳海槽有孔虫壳体强烈富集Sr,P,Mn和Ba,富集Li,U,Th,Sc,Co,Pb,Zn,Cr,Rb,Y,Sb和轻稀土元素,弱富集V,Ga,Zr,Nb,Cd和中稀土元素,相对贫Ge,Mo,In,Sn,Cs,Hf,Ta,W,Tl,Bi和重稀土元素,海水中微量元素的背景含量和生物活动对微量元素的选择性吸收是有孔虫壳体中微量元素发生富集和贫化的主要机制,冲绳海槽有孔虫壳体的稀土元素配分模式与海水和太平洋有孔虫的有明显差异,表现出中稀土元素相对富集,并具有微弱的负Ce异常.有孔虫壳体的Sr,Nd同位素比值也与大洋海水不同,分别为0.709769和0.512162,前者略高于大洋海水,后者略低于大洋海水,表明冲绳海槽海水明显受大陆河水影响.Abstract: Trace elemental associations and Sr,Nd isotopic compositions are of important for recognition of biogenic material from mixed marine sediments.The foraminifera shell of the Okinawa Trough strongly enriches Sr,PMn and Ba,enriches Li,U,Th,Sc,Co,Cu,Pb,Y,Zn,Cr,Rb,Sb and light rare earth elements,slightly enriches V,Ga,Zr,Nb,Cd and middle rare earth elements,and is relative short of Mo,In,Sn,Cs,Hf,Ta,W,Tl,Bi and heavy rare earth elements.The mechanism of element enrichment of foraminifera is the concentrations of trace elements in sea water and selective absorption of trace elements during foraminifera living,as well as the geochemical affinity between major elements and trace elements.The REE partitioning pattern of foraminifera shell of the Okinawa Trough shows enrichment of middler are earth elements and slightly negative Ce anomaly,which are different from those of foraminifera of the Pacific Ocean.The Sr,Ndisotopic ratios of the Okinawa Trough foraminifera are 0.709769 and 0.512162,respectively,which are different not only from those of oceanic water,but also from those of river water of China.Mainland,the former is slightly higher than that of oceanic water,but much lower than that of river water,the latter is slightly lower than that of oceanic water,but higher than that of river water,which demonstrates that the Okinawa Though sea water has been influenced by river water of China.Mainland.
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Key words:
- foraminifera shell /
- trace element /
- Sr-Nd isotopes
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