Granulites of Bhopalpatnam and Kondagaon belts, Bastar craton, M. P.: petrological and fluid inclusion studies

The Bhopalpatnam and Kondagaon granulite belts (BGB, KGB) occur surrounding the Bastar craton of central India. This paper deals with the geology, mineralogy and the fluid characteristics of these two belts. The geology of the two belts indicate that they abound in metasedimentary swathes. The metamorphic P-T conditions of the BGB range from 6 to 9 kbar at temperatures of 750°C, whilst those of the KGB vary from 4 to 6 kbar at temperatures of 700°C. The BGB shows an IBC path, while the KGB exhibits a dominant ITD path. These trends, based on mineral chemistry, are corroborated by fluid-inclusion studies. The lithologies of the BGB exhibit high-density CO₂ inclusions that represent the remnants of peak metamorphism. In contrast, the CO₂ inclusions of the KGB are of low density, indicative of post-peak conditions. The studies suggest that the CO₂-rich fluids may not have come from the supracrustal sediments. An external source, possibly underplated basalt, could have supplied the heat and the supercritical fluids. Based on lithological similarities, it can be stated that the BGB is an extension of the late Archaean Karimnagar granulite belt. The important problem which is still to be solved is the junction of the late Archaean BGB with the Eastern Ghats granulite belt.