Petrography and Heavy Mineral Analysis of Barail Sandstones, Zubza Village, Kohima District, Nagaland India

In this paper petrographic and heavy mineral account of the Barail sandstones of Zubza village area is presented. The sandstones are dominated with Quartz arenite. Few other petrographic types are Argillaceous Siltstone, Laminated Siltstone, Micaceous Quartz Arenite and Lithic Glauconitic Arenite. The modal composition reveals that the percentage occurrences of different constituents of these Barail sandstones range as Quartz (39.85% to 64.10%, Feldspar 5.27% to 8.25%, and Rock fragments 4.53% to 14.25%). However the rich Monocrystalline quartz implies their derivation from intrusive igneous rocks. The Predominance of unit quartz and undulose quartz collectively corroborate the dual sources of low rank metamorphic, and plutonic sources of variable pressure effects. QFL triangular plot infers the derivation of the sandstones from recycled orogenic sources. QmFRt triangular plot shows that the provenance of these Barail sandstones were mainly of mixed and dissected arc types. However, few of them also show their derivation from quartz arenite recycled origin. Heavy mineral study reveals that the Barail sandstones contain both opaque and non –opaque minerals. The non-opaque minerals include Zircon, Tourmaline, Rutile, Sillimanite, Kyanite, and Staurolite. ZTR maturity indices vary from 82.059% to 96.082% with an average 88.538%. ZTR triangular diagram points out the predominance of tourmaline and zircon which further infers the derivation of the Barail Sandstones from both metamorphic and igneous sources.