Ultrahigh-temperature granulites from the southern margin of the Madurai Block, India: Petrology, metamorphic phase equilibria and zircon-monazite U–Pb geochronology

The Madurai Block is the largest crustal block in the Southern Granulite Terrane of India, and is composed of a dominantly Neoarchean northern segment, Paleoproterozoic central segment, and dominantly Neoproterozoic southern segment. Here we investigate garnet – orthopyroxene – spinel – cordierite – plagioclase – K-feldspar – quartz bearing granulites from the southern margin of the Madurai Block. We present results from petrology, mineral chemistry, pseudosection modeling, geothermobarometry, and U–Pb geochronology of zircon and monazite. The prograde minerals assemblages comprise Grt + Pl + Qtz + Mt. + Ilm + Sill which define pressure-temperature (P-T) conditions of 7.2–7.8 kbar and 900–980 °C. The peak minerals assemblages of Grt + Pl + Opx + Crd + Qtz + Mt. + Ilm yield P-T conditions of 5.8–6.5 kbar and 980–1030 °C. Subsequent cooling and decompression are inferred by the break down of garnet at 2–4 kbar and