东海周边中小型河流沉积物锶钕铅同位素组成及其物源示踪意义

Sr-Nd-Pb isotopic compositions in the sediments of the middle and small rivers around the East China Sea and the implications for tracing sediment sources

通过对东海周边9条中小型河流沉积物进行锶钕铅(Sr-Nd-Pb)同位素测试,分析了其组成特征及其物源指示意义。结果表明,^(87)Sr/^(86)Sr、^(143)Nd/^(144)Nd、^(206)Pb/^(204)Pb平均值分别为0.719 056、0.512 056和18.614 94。Sr-Nd-Pb同位素组成主要受地质背景和风化作用的制约,空间变化规律明显,可作为区分不同来源河流沉积物的有效指标。统计结果确立出三个端元值,分别为台湾岛东部河流(^(87)Sr/^(86)Sr-0.713 355,ε_(Nd)--8.488)、台湾西部河流(^(87)Sr/^(86)Sr-0.718 804,ε_(Nd)--12.375 7)和大陆东南部河流(^(87)Sr/^(86)Sr-0.722 195,ε_(Nd)--11.944 4)。确立这些端元可为认识中国东部陆架区沉积物"源-汇"过程及陆海相互作用提供科学依据。

The Sr-Nd-Pb isotopic data from the sediments of nine middle and small rivers around East China Sea are analyzed to study the composition character and the provenance of sediments. The results indicate that the average values of the ^87Sr/^86Sr,^143Nd/^144Nd,^206Pb/^204Pb are 0.719 056, 0.512 056 and 18.614 94, respectively. The Sr-Nd-Pb composition is constrained by geological background and weathering conditions and the spatial variation pattern could be effectively used to reveal different sources of river sediments. The results identify three end-members which are the eastern Taiwan island rivers （^87Sr/^86Sr-0.713 355,εNd-- --8.488）, the western Taiwan island rivers （^87Sr/^86Sr-0.718 804, end-- --12.375 7）and the southeastern continent rivers （^87Sr/^86Sr-0.722 195, end-- --11.944 4）. It could supply the evidence for the research of the ＂source to sink＂process of eastern Chinese continental sediments and the interaction between land and sea by determining these end- members.