PETROGRAPHY, MINERALOGY AND ELEMENT DISTRIBUTION IN THE CHARMURIA LIMESTONE, CHHATTISGARH BASIN, MP

The Charmuria limestone is characterized by grey-black colour, bedding structure, fine grain size and authigenic pyrite cubes. Petrographica lly a minimicrite, the rock exhibits a texture composed of dark crinkl ed and light coloured laminae of lime mud. Pyrite has discordant relat ionship with laminae, whereas silt-sized terrigenous particles are pre sent in the interlaminar areas. Mineralogically the limestone is made up of low Mg-calcite and quartz. Trace element distribution indicates that the original mineralogy at the time of deposition was calcitic in nature and its distribution in the rock was controlled by the deposit ional/diagenetic conditions as well as the detrital clastics supplied into the basin. The depositional environment of the limestone is inter preted as shallow marine lagoonal condition and the site of deposition was very near to shore. The dysaerobic to anaerobic condition which i s attributable to the restricted circulation of water and the concomit ant slow-sedimentation rate were responsible for the development of au thigenic pyrite and grey-black colour of the limestone.