黄河和长江沉积角闪石亲石元素地球化学特征对比与物源辨识

为辨识黄河和长江入海沉积物中角闪石的物源差异,对采自黄河口段、长江口段以及废黄河口和苏北沿岸,共26个样点、38组粒度粗细不同的碎屑角闪石进行了矿物元素地球化学测试,获得了这些角闪石群体的50种常量和微量元素含量值.结果表明:不同粒级测量的同源角闪石元素含量除少数大离子活泼元素相对偏差较大之外,大部分元素含量差异性较小...

Comparison of Geochemical Characteristics of Lithophile Elements of Amphibole: Identification of estuarine sediment provenance,Huanghe River and Changjiang River

Samples from 26 locations on the Huanghe River Estuary， the Changjiang River Estuary， the abandoned Huanghe River Estuary and the northern Jiangsu coast were analyzed to identify the provenances of amphibole in sediments from the Huanghe and Changjiang Rivers. Thirty-eight groups of different-size detrital amphibole particles were tested by element geochemistry （ICP-OES and ICP-MS）. Fifty major and trace element contents were obtained for every amphibole group. The results show homologous amphibole element content for the different particle sizes. Except for the relatively large deviation of a few large ion-active elements， most of the element content differences are relatively small. This indicates that the provenances of the amphiboles from the Huanghe River and Changjiang River have individual characteristics in common. The collective geochemistry of amphibole from the two estuaries showed high Ca， Mg， low Na， K content. The large-ion lithophile elements occupy the A and B sites of the amphibole structure， and the constant elements K， Na， Ca and trace elements Sr ， Ba， Rb， Pb， Th， U etc. are closely related， and have a wide range of isomorphism. These large-ion trace elements fluctuate greatly in the homologous samples， with medium to large average differences between heterogeneous samples. The high-field-strength profile elements （e.g.， Zr， Hf， Sc， Y， REE， Nb， Ta， etc.） have undergone complex isomorphic substitution in the structure of the amphibole； the constant elements （e.g.， Fe， Mg， Al， Ti and Mn） occupy the C sites. Their content is relatively stable， with only small internal variation in homologous samples. In heterogeneous samples the content of various elements and the ratio between elements differ greatly， especially the contents of Be， Y， Zr， Hf and Sm， and the ratios of Zr/Sc， Zr/Rb， Zr/Nb， Zr/Y， Y/Hf， K/Nb， Sc/Hf， Y/Nb and Rb/Hf. These show significant group differences in the amphiboles from the Huanghe River and from the Changjiang River， which is useful for indicating provenance. Scatter plots of the ratios between multiple-group elements act to qualitatively identify source minerals， and multiple high field-strength trace element content allows a quantitative assessment of the provenance by using chemical mass balance source analysis and a least-squares algorithm.