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.