Assembly and dispersal of South Indian, Yilgarn and East Antarctic cratons

What is it about?

An Archaean continent ‘SIWA’, an acronym for South India – Western Australia, comprising the Bastar–Dharwar craton, the Yilgarn craton, the Napier complex and the Vestfold Hills has been identified from palaeomagnetic and spatio-temporal data. This assembly was dispersed in three phases with development of the proto-Indian ocean. The first and second events at ~2350 Ma and ~2000 Ma were related to the separation of the Yilgarn craton, and the Napier Complex, respectively, to form a proto Indo-Antarctic ocean and the Cuddapah basin. The proto-ocean was closed at ~1650 Ma by the collision of the Lambert terrane of East Antarctica and the Bastar–Dharwar craton. This collision associated with ultra-high temperature granulite facies metamorphism is identified in the southern domain of the Eastern Ghats and the Oygardens domain of the East Antarctica. The third extensional event between 1500 and 1200 Ma was associated with the separation of the Vestfold Hills block and a second phase of opening of the proto-Indian ocean, and development of a series of basins on the western side of the Eastern Ghats (the Chhatisgarh, Khariar, Ampani, Indravati and Sabari basins). The closing of this ocean basin during the Eastern Ghats–Rayner orogeny at ~950 Ma was related to the amalgamation of India and East Antarctica to form the supercontinent Rodinia. During Neoproterozoic, this part of Rodinia was involved in orogenic collapse/extension, and deposition of the Sodruzhesvo Group. The Pan-African Prydz Bay orogeny at ~550 Ma caused closing of the basin to form the East Gondwana Land.

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Why is it important?

* New ideas related to the development of the Eastern Ghats of India are proposed. * Development of Cuddapah basin is explained. * Positions of the Napier complex and Vestfold Hills during Archean is identified.