Iron Oxide-Copper-Gold Mineralization at Thanewasna, Western Bastar Craton

Iron oxide-copper-gold (IOCG) at Thanewasna, Maharashtra, India is a new genetic type of ore deposit, being reported from the western margin of Bastar craton, based on integrated field, drilling, mineral chemistry and Raman microprobe studies. It is the fourth such IOCG type being reported from India. Hydrothermal mineralization is structurally confined to en echelon dilatational quartz-chlorite veins along NW-SE trending brittle-ductile shear zone hosted in calc-alkaline granitoid. The mineralization is characterized by chalcopyrite, magnetite and barite which occur as dissemination, stringers and veins associated with hydrothermal K-alteration and chlorite alteration. Chemical analysis shows significant amounts of Cu, Fe, Ba and anomalous Au content. Ore petrography and scanning electron microscope and electron probe micro analyser studies show assemblages of Cu-Fe-Au-Ag-Ni-Ba-REE minerals typical of IOCG type deposits at Thanewasna. Ore textures, mineralogy and alteration characteristics are typical of IOCG-type deposits, further supported by mineral chemistry of magnetite (V versus Ti/V) using EPMA, and thus define a IOCG metallogenic province in Thanewasna area with significant implications for future exploration.