SIZE CHARACTERISTICS AND MINERALOGY OF SUSPENDED SEDIMENTS OF THE GANGES RIVER, INDIA

With a mean annual flow of 5.9 x 10(11) m(3) yr(-1) and sediment load of 1600 x 10(12) g yr(-1), the Ganges river ranks second and third, respectively, in terms of water flow and sediment load among the world's rivers. Considering the enormous sediment transport by Ganges to the Bay of Bengal, a study was conducted on the size distribution and mineral characteristics of the suspended sediments of the Ganges river and is reported here. Most of the sediment load has a size range between <4-5.75 phi. The sediments are mostly medium to coarse silt and are poorly sorted. Mica dominates among the clay minerals, followed by chlorite, vermiculite, kaolinite, and smectite. Due to differences in geology, smectite becomes a major clay mineral in downstream rivers. At Calcutta, the clay mineral transport in millions of tons per year is 18,464, 8000, and 2147, for mica, smectite, and chlorite, respectively.