Mineralogical composition and spatial variation of suspended sediments in a 2nd order channel of the Brahmaputra River in Majuli, Assam, India
- 1Department of Geological Sciences, Gauhati University, Guwahati, Assam, India
- 2Department of Geological Sciences, Gauhati University, Guwahati, Assam, India
Int. Res. J. Environment Sci., Volume 6, Issue (11), Pages 16-22, November,22 (2017)
The Brahmaputra River flows across Assam in a braided pattern with large discharge and heavy sediment load. The present study investigates the post-monsoon mineralogical variations in the suspended load in a 2nd order channel of the Brahmaputra River in Majuli, Assam. The channel flows along the southern bank of Majuli. Representative suspended sediment samples were collected from different locations and depths along the 2nd order channel, which were subsequently subjected to laboratory analysis for the determination of amount of suspended load as well as their mineralogical content. The suspended load varies from 0.337 gm/l to 1.77 gm/l. X-ray Diffraction analysis of the sediments indicate the presence of quartz, chlorite, chamosite, strontianite, sanidine, orthoclase, tourmaline, albite, oligoclase, augite, hornblende, biotite, muscovite, enstatite, epidote calcite, dolomite, hematite, goethite, gypsum, garnet, apatite, tourmaline, zircon, silimanite, kyanite, rutile, zoisite, clinozoisite and glauconite. The clay minerals varieties found are illite, montmorillonite and chlorite. A decrease in the amount of suspended load is observed from upstream towards the downstream part of the channel due to drop in stream power and change in flow direction of the 2nd order channel in its downstream portion. No clear segregation of minerals is observed along the course of the river channel.
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