Provenance and Diagenetic Features of Sandstones in the Surma -Tipam Transitional Sequence exposed in the Schuppen Belt, Naga Hills, NE India

The Schuppen Belt, a part of the Indo-Burma Ranges is basically comprised of molasses of Tertiary age. This tectono–stratigraphic belt is restricted by two major thrust faults, namely Disang and Naga. In the southern part of the Naga Hills a significant part is occupied by Surma–Tipam Transitional Sequences (STTS). This study deals with the petrography, provenance, and tectonic setting of the STTS sandstones. The sandstones are classified as arkose and arkosic wacke types. The major contribution of detritus has been observed from the recycled orogen, dissected arc, transitional continental and basement uplift. The geochemistry data reveals that the sandstones were derived from a collisional setting of an active continental margin. The low degree of chemical maturity indicates that the sandstones were deposited in an arid climatic condition. The diagenetic signatures observed in these sandstones such as, point, long and concavo-convex grain boundary, albitization, crushing and squashing of quartz grains, warping of mica around detrital grains, and bending of mica suggest early to a late stage deep burial diagenesis.