Petrological and geochemical studies of Tikak Parbat Formation, Barail Group in parts of Belt of Schuppen, Nagaland, Northeast India

Abstract

Petrography and geochemistry of clastic rocks from the Oligocene Tikak Parbat Formation (Barail Group) in the Tiru Valley, located northeastern parts of the Belt of Schuppen, have been investigated to understand their provenance, paleoweathering, and tectonic settings. The Tikak Parbat Formation (TPF) is characterized by alternations of thin to thickly bedded, fine - medium grained, cross - stratified, ripple laminated sandstone, carbonaceous shale and coal seams. The average recalculated modal composition Q56 F7 R37 and geochemical proxies, classified TPF sandstone into two categories as lithic arenite to lithic-wacke. The chemical indices such as chemical index of alteration (CIA), chemical index of weathering (CIW), plagioclase index of alteration (PIA), and ternary diagrams (A–CN–K and (A–K)–C–N) indicated that the TPF sediments has undergone intense weathering under semi-arid to semi-humid climatic conditions. The index of chemical variability (ICV) indicates a high maturity. The results of this study suggest that the TPF sediments were mainly derived from recycled orogenic sources, with minor contributions from mixed and transitional continental and were deposited in a stable continental (passive) margin setting analogous to that of an Atlantic-type continental margin set up.