孟加拉湾中部表层沉积物常微量元素地球化学:物源指示意义

通过对取自孟加拉湾中部的110个表层沉积物样品进行了常微量元素测试分析，探讨了其物质来源。在所有测试元素中，Si含量最高，其次为Al，且这两种元素的分布特征基本一致。化学蚀变指数（CIA^*）平均值为72.07，指示研究区沉积物风化程度位于喜马拉雅源区和印度源区沉积物之间。因子分析和判别函数计算分析表明研究区沉积物主要来自喜马拉雅源区和印度源区。使用Ti标准化后的元素比值反演模型估算的喜马拉雅源区和印度源区对研究区沉积物的相对贡献比例分别为83.5%和16.5%。其中，喜马拉雅源区对研究区东部沉积物贡献相对较大，而在研究区西部印度源区贡献比例相对东部为高。喜马拉雅源区物质向研究区输运的主要动力机制包括浊流及其溢流、表层季风环流携带的河流冲淡水，而印度源区物质主要通过表层季风环流特别是东印度沿岸流向研究区输运

Major and trace element geochemistry of the mid-Bay of Bengal surface sediments: implications for provenance

The major and trace elements in 110 surface sediment samples collected from the middle of the Bay of Bengal (mid-Bay of Bengal) are analyzed to investigate provenance. Si levels are highest, followed by Al, and the distributions of these two elements are identical. The average CIA^* (chemical index of alteration) value is 72.07, indicating that the degree of weathering of the sediments in the study area is intermediate between those of sediments of the Himalayan and Indian rivers. Factor analyses and discrimination function analyses imply that the two main provenances are the Himalayan and the Indian continent. The inverse model calculation of the Ti-normalized element ratios of the Bay of Bengal sediments indicate an estimated average contribution of 83.5% and 16.5% from the Himalayan and peninsular Indian rivers to the study area, respectively. The Himalayan source contributes more sediment to the eastern part of the study area, whereas the western part receives more sediment from the Indian Peninsula than did the eastern part. The primary mechanisms for deposition of sediments in the study area are the transport of Himalayan matter by turbidity currents and river-diluted water and the transport of Indian matter to the study area by a surface circulation in the Bay of Bengal, particularly the East India Coastal Current.