Clay mineral compositions in surface sediments of the Ganges-Brahmaputra-Meghna river system of Bengal Basin, Bangladesh
Clay mineral compositions in surface sediments of the Ganges-Brahmaputra-Meghna river system of Bengal Basin, Bangladesh
复制标题
DOI：
10.1016/j.margeo.2019.03.007
复制
发表时间：
2019-06
期刊：
影响因子：
2.9
通讯作者：
M. H. R. Khan;Jianguo Liu;Shengfa Liu;A. Seddique;Li Cao;Ananna Rahman
中科院分区：
文献类型：
--
作者：
M. H. R. Khan;Jianguo Liu;Shengfa Liu;A. Seddique;Li Cao;Ananna Rahman
粘土矿物是识别河流和海洋沉积物来源和迁移模式的重要指标。恒河、雅鲁藏布江和苏尔玛-梅克纳河是孟加拉盆地最重要的河流，它们将喜马拉雅山脉的大量沉积物带入孟加拉湾。利用X射线衍射（XRD）分析了恒河-雅鲁藏布江-梅克纳河（GBM）水系132个表层沉积物样品的粘土矿物为了显示孟加拉湾主要河流沉积物中粘土矿物组合从上下游的变化，并验证这些沉积物排入孟加拉湾后粘土矿物作为沉积物物源重要指标的有效性，邻海。结果表明，GBM水系粘土矿物组合以伊利石为主（平均66%），其次为蒙皂石、高岭石和蒙脱石（分别为8%、8%和17%）。蒙皂石在恒河沉积物中具有特征性，其含量（23%）高于雅鲁藏布江（2%）和SM河（1%）;然而，SM河沉积物中的蒙脱石含量（21%）较高，雅鲁藏布江沉积物中的伊利石含量较高（77%）。下游，恒河中蒙皂石的百分比显著增加，但SM河沉积物中高岭石的百分比略有增加。由于雅鲁藏布江和SM河流量的连续混合，该水系沉积物的粘土矿物组合发生了很大变化，蒙皂石百分比从恒河的23%下降到GBM河的8%，经过恒河-雅鲁藏布江汇流河的12%。
Clay minerals are significant indicators that can be used to identify sources and transport patterns of both fluvial and marine sediments. The Ganges, Brahmaputra, and Surma-Meghna (SM) rivers are the most important rivers of the Bengal Basin (BB), loading a large amount of sediments from the Himalayas into the Bay of Bengal. Clay minerals of 132 surface sediment samples from the Ganges-Brahmaputra-Meghna (GBM) river system have been analyzed with X-ray diffraction (XRD) to show the variation of clay mineral assemblages in the sediments from upstream to downstream for the major rivers of the BB and to verify the validity of clay minerals as an important index for sediment provenance in the Bay of Bengal after these sediments are discharged into the neighboring seas. The results show that the clay mineral assemblage in the GBM river system consists dominantly of illite (average 66%), with smaller amounts of smectite, kaolinite, and chlorite (8%, 8%, and 17%, respectively). Smectite is diagnostic in the Ganges River sediments, with a higher content (23%) than that in the Brahmaputra (2%) and the SM River (1%); however, chlorite (21%) is high in the SM River sediments and the Brahmaputra River sediments have a high illite percentage (77%). Downstream, the smectite percentages in the Ganges River increase significantly, but the kaolinite percentages in sediments of the SM River increase slightly. Due to the continuous mixture of first the Brahmaputra River and then the SM River discharge, the clay mineral assemblages of this river system's sediments change greatly, e.g., smectite percentages decrease from 23% in the Ganges River to 8% in the GBM River via the stretch with 12% in the Ganges-Brahmaputra confluence river.