Petrological study of granulites from Antarctica-India-Madagascar region and the formation of the Gondwana Supercontinent

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The Gondwana supercontinent is known as the only mega-continent present at 550-600 Ma. We performed field geological survey of collisional orogenic belts within the supercontinent, which corresponds to Antarctica - South India - Madagascar region, and collected various samples of high-grade metamorphic rocks and associated igneous rocks. Detailed petrological and geochronological studies on the rocks demonstrated that this region corresponds to a paleo-suture zone along which various high-pressure and high-temperature metamorphic rocks as well as remnants of oceanic plates (ophiolites) have been recognized, particularly from the Palghat-Cauvery suture zone in southern India. We also found crustal blocks with older ages of 3.2 Ga, 2.5 Ga, and 0.7-0.8 Ga from southern India and Antarctica. These older blocks within the 550-600 Ma suture zone might correspond to microcontinents or island arcs which accreted to Archean continents during the amalgamation of the Gondwana supercontinent.