Late Quaternary Climate and Provenance Signals of Brahmaputra River Sediments in the Sylhet Basin, Bangladesh

A high-resolution record of Brahmaputra River sediments is investigated from a 200-m borehole record from the Sylhet region in Bangladesh, a rapidly subsiding tectonic tectonic basin that preserves a nearly continuous Late Quaternary sequence. The percent abundance of major clay minerals down the core was determined by x-ray diffraction techniques. The ratio of smectite and kaolinite versus illite and chlorite was calculated as a proxy for the extent of chemical versus physical weathering. Other mineralogical studies of the Bengal Fan have found a correlation between climate and the record of clay mineralogy in the sediments (e.g. Debrabrant et al., 1996). Interestingly, this study did not yield such a clear correlation, suggesting that other factors, such as provenance or weathering, could play an important role in the preservation and hence the climatic signal as interpreted from clay mineralogy.