Petrography and diagenesis of sandstones from renji formation in and around Phiphima, Dimapur, Nagaland, India

Abstract

Renji Formation, the youngest unit of Barail Group, is characterized by massive, hard, thicklybedded and ferruginous sandstones intercalated with minor shales. Sedimentary structures observed are load cast; ripple marks, plane and fine cross laminations.Petrographic compositions of the studied sandstones suggest their derivation from a mixed provenance having contributions from all possible sources dominated by a sedimentary provenance. Sediments of the study area have undergone both early and late stages of diagenesis and are influence by chemistry of sea water, and increasing depth. Diagenetic features preserved in the siliciclastics of the study area suggest a depth range of 1.5 to 2.5 km and a temperature above 100°C.