THE BALLET OF INDIAN PLATE DURING THE ASSEMBLY AND BREAKUP OF THE PROTEROZOIC SUPERCONTINENTS

Four major Paleoarchean nuclei: the Dharwar, the Bundelkhand, the Bastar, and the Singhbhum cratons–were sutured and stabilized into a single, unified Indian craton at the end-Archean with the onset of plate tectonics. The Indian craton was part of three ancient supercontinents during the Proterozoic: Columbia (~1.8-1.3 Ga), Rodinia (~1.1 Ga-750 Ma), and Pannotia (~633-573 Ma). Eastern India and Enderby Land (Antarctica) collided around 1.5 Ga along the southern Eastern Ghats mountain range during the assembly of Columbia. During this collision, the exotic terrane of the Ongole Domain was transferred from the Napier Complex of Antarctica to the southern Eastern Ghats Belt of India. It is likely that the source of the detrital zircons in the protoliths of the Ongole terrane came from the Napier complex of Enderby Land. The younger Proterozoic sedimentary rocks of the Pranhita-Godavari Valley also show a similar provenance. The Mahanadi and the Godavari rift basins India were formed when Columbia began to break apart ~1.5-1.35 Ga. The breakup of Columbia was followed rapidly by the assembly of another supercontinent, Rodinia. The Rodinia has North America at its core and is surrounded Grenville-age orogenic belts (~1.1 Ga). In the Rodinia assembly, the Eastern Ghats Grenville-age orogen is linked with the coeval Rayner orogen in Antarctica. Several different reconstructions of Rodinia have been proposed. In some, India is omitted from Rodinia altogether. In other reconstructions India is placed outboard of East Antarctica or Australia. Rodinia remained intact for ~300 Ma. Around 750 Ma, Rodinia split into two large continents – North Rodinia and South Rodinia. The third Proterozoic supercontinent, Pannotia, formed at the very end of the Proterozoic when the two halves of Rodinia collided with the Congo continent during the Pan-African orogeny (~633 Ma). Pannotia broke apart 560 Ma with the opening of the Iapetus and Ran oceans. In Pannotia assembly, Laurentia was located adjacent to two major South American cratons: Amazonia and Rio de la Plata. Africa was located at the center, surrounded by the rest of Gondwana: South America, Arabia, Madagascar, India, Antarctica and Australia. The breakup of Pannotia might have caused the rise of the sea level and other environmental changes that triggered the Cambrian explosion.