Geochemical Investigations of the Disang Sandstones of Botsa, Nagaland, NE India

The Disang sediments of Botsa constitute a flysch facies of Upper Cretaceous - Eocene age. They comprise a thick sequence of splintery shales with intercalations of thin, flaggy sandstones/siltstones of greywacke composition. These are recycled sediments of a mixed source, including igneous and low rank metamorphics, where Semi-Humid climatic conditions prevailed and moderate intracrustal differentiation processes took place. These chemically mature sediments were deposited at plate interiors, in an exogeosynclinal setup, along a passive continental margin. This was a marine environment where low ventilation and Eh conditions prevailed.