Heavy Mineral and Clay Mineralogy of Recent Fluvial Sediments Along Brahmaputra River of Dibrugarh District, Assam

This study area delves into the geological saga of the Brahmaputra River in Dibrugarh District, Assam, exploring its profound impact on regional evolution amidst extensive layers of contemporary alluvial sediments, including Older Alluvium, High-Level Terraces, and New Alluvium, visible in natural cut bank formations along the river's course. The recent fluvial sedimentary deposits were meticulously surveyed and sampled at ten distinct sites from Tingkhan – Nagakheliya Gaon, Oakland Ghat, Madhupur Ghat, and Dolphin View Point, Chabua, evenly distributed from north-north-east (NNE) to south-west-west (SWW) along the river. The primary objective of this study is to conduct a thorough analysis of heavy minerals percentages through microscopic slide analysis, aiming to assess the maturity of river sediments utilizing the Zircon-Tourmaline-Rutile (ZTR) maturity index and to elucidate clay mineralogy employing X-ray diffraction techniques of recent fluvial sediments. The findings of these analyses provide valuable insights like, heavy minerals derive from the sediments diverse NNE and SWW sources, with ultra-stable and unstable heavy minerals assemblages suggesting sediments source from high-grade metamorphic and acidic igneous rock regions. The ZTR maturity index of sediments increases in the direction from NNE to SWW. Also rounded Zircon-Tourmaline-Rutile grains imply reworked sediment contribution, while subrounded to sub-angular grains hint at potential first-cycle origin. X-ray diffraction analyses highlight peaks of clay matrix (Kaolinite, Chlorite), and the abundance of non-clay matrix (Garnet, Siderite, Pyrite specially Quartz). This sedimentary record resonates with a captivating amalgamation of influences from the northeastern Himalayas and Naga Hills, coupled with dendritic sediment depositions.