Diagenesis of the Dark Grey Limestone of Nagod Formation, Madhya Pradesh

The rocks of the Vindhyan supergroup show evidences of deposition in a shallow marine environment, the depositional basin being similar to 'epeiric sea'. The dark grey limestone unit of the Nagod Limestone Formation is a low magnesian limestone and is invariably an intrasparite or oosparite with variable amounts of authigenic cement spar, neomorphic spar and micrite occupying intra- and inter-allochemical pore spaces. Fibrous nonferroan calcite, dog tooth fringe of nonferroan calcite, drusy mosaic of ferroan calcite and syntaxial rim cement, constitute the different types of cements noticed. Authigenic minerals like dolomite, quartz, plagioclase and pyrite are present in small quantities. Based on the precipitational and recrystallisation fabrics of the calcite and the presence of different authigenic minerals, the diagenetic history of the limestone is worked out.