Clay mineralogy and diagenesis of disang siliciclastic rocks from Chakhabama area, Nagaland, India

The Disang siliciclastics (Cretaceous-Eocene) exposed in and around Chakhabama within the Kohima and Phek districts of Nagaland form a part of the Kohima synclinorium within the Inner Fold Belt of Naga Hills. These rocks possess a thermodynamically stable eogenetic assemblage of authigenic minerals that include chlorite, illite, quartz, carbonates and pyrite. Bending, fracturing, crushing of the minerals and the presence of silica and carbonate cements are a manifestation of both the physical and chemical processes that characterize high grade burial diagenesis.