Petrography, Mineral Chemistry and Geothermobarometry of the Inukurti Anorthosite Complex and Associated Rocks from the Nellore Schist Belt, Andhra Pradesh

The Inukurti Anorthosite Complex (IAC) forms a small elliptical dome (15 x 10 km) within the Archaean metamorphosed volcano-sedimentary sequences of the Nellore Schist Belt (NSB) The IAC comprises dominantly of anorthositic rocks, which are cut by mafic sills and dykes, volumetncally insignificant lenses and bands of dionte occur along its periphery All the rocks are deformed and metamorphosed under amphibohte-facies conditions but exhibit relict magmatic textures despite metamorphic recrystallisation and deformation The minerals from anorthosites diontes and amphibohtes exhibit compositional characteristics distinct to each group

Garnet-hornblende plagioclase-quartz equilibria from the IAC indicate a narrow range of metamorphic equilibration temperature between 644 and 570 °C, but a broad range of pressure between 76 and 27 kbar Geothermobarometry on zoned garnet porphyroblasts indicates that the rocks of the IAC were subjected to decompression of the order of about 5 kbar from 76 to 27 kbar related to rapid exhumation