Os‐Sr‐Nd results from sediments in the Bay of Bengal: Implications for sediment transport and the marine Os record

作者：Anne‐Catherine Pierson‐Wickmann, Laurie Reisberg, Christian France‐Lanord, Herman R. Kudrass · 发表于：Paleoceanography · 年份：2001 · DOI：10.1029/2000pa000532 · 被引用次数：51 · 研究领域：Geology and Paleoclimatology Research、Geochemistry and Elemental Analysis、Geological formations and processes

Sr, Nd, and Os isotopic data are presented for sediments from diverse locations in the Bay of Bengal. These data allow the samples to be divided into three groups, related to their sedimentary contexts. The first group, mainly composed of sediments from the shelf off Bangladesh and the currently active fan, has Sr and Nd characteristics consistent with a dominantly Himalayan source. Their 187Os/188Os ratios (∼1.2‐1.5) show that the average detrital material delivered by the Ganga‐Brahmaputra (G‐B) river system is not unusually radiogenic. A large difference in 187Os/188Os ratio exists between these Bengal Fan sediments and Ganga bedloads (187Os/188Os ∼2.5, Pierson‐Wickmann et al. [2000]). This difference mainly reflects addition of a less radiogenic Brahmaputra component, though mineralogical sorting and loss of radiogenic Os during transport may also play some role. The second sample group contains sediments from elsewhere in the Bay, particularly those located on the continental slope. They display Os isotopic compositions (0.99–1.11) similar to that of present seawater and higher Os and Re concentrations. These characteristics suggest the presence of a large hydrogenous contribution, consistent with the lower sedimentation rate of these samples. Sr and Nd ratios indicate that a significant fraction of these sediments is derived from erosion of non‐Himalayan sources, such as the Indo‐Burman range. These observations could be explained by the deflection of sediments from the...