Heavy Mineral Composition and Sources of Himalayan Neogene Sediments Occurring along the Garu-Likabali Road Section, West Siang District, Arunachal Pradesh, India

The Neogene sedimentary sequence of the Arunachal Himalayas is represented by the Dafla, Subansiri and Kimin Formations. Their systematic heavy mineral analysis along the Garu-Likabali Road section indicates that the heavy mineral assemblage is composed of fifteen heavy mineral varieties comprising of andalusite, biotite, chloritoid, chlorite, epidote, garnet, hornblende, hypersthene, kyanite, muscovite, rutile, sphene, staurolite, tourmaline and zircon, besides opaque minerals. The assemblage points towards a complex sediment provenance for the Neogene sedimentary sequences with sediment inputs from pre-existing igneous, metamorphic and sedimentary rocks. The boundary between the Dafla and Subansiri Formation in the region can be demarcated on the basis of disappearance of Hypersthene in the heavy mineral suite of the older Dafla Formation as well as appearance and persistence of staurolite in the same Formation.