Garnet-sillimanite-cordierite-quartzbearing assemblages from early Archean supracrustal rocks of Bundelkhand Massif, Central India

Abstract

The Bundelkhand gneissic complex includes the highgrade metapelites, amphibolites, calc-silicates and granite-gneisses, which are invaded by 3.2-3.3 Ga old tonalite-trondjemite-grainodiorite. Detailed petrographic studies and EPMA analyses of metapelites reveal the presence of garnet-sillimanite-cordierite- biotite-K-feldspar-plagioclase-quartz, biotite-sillimanite- cordierite-K-feldspar-plagioclase-quartz and garnet-sillimanite-biotite-K-feldspar-plagioclase-quartz mineral assemblages which belong to upper amphibolite to granulite facies rocks and have been reported for the first time from the Bundelkhand craton. The average P-T conditions estimated by different models of geothermobarometry yield the core composition at 730°C/5.4 kbar and rim composition at 640°C/5.1 kbar.