ASSEMBLY AND FRAGMENTATION OF THE PROTEROZOIC SUPERCONTINENTS COLUMBIA AND RODINIA: NEW U-PB AGE DATA FROM THE EASTERN GHATS BELT, INDIA

New SHRIMP-RG zircon U-Pb ages demonstrate the operation of two complete Wilson cycles in the Eastern Ghats Belt (EGB), India reflecting the accretion and rifting of Columbia and Rodinia. The Cuddapah traps, Bastar mafic dikes, Kandra ophiolite and Kondapalli A-type granites record the first extensional event along the eastern margin of India between 1890 and 1850 Ma. These rifted continental margins and oceanic basins were closed by arc-continent and final continent-continent collision at 1.6 Ga, related to the assembly of the supercontinent Columbia. Extensive ultra-high temperature granulite-facies metamorphism accompanied this Paleoproterozoic suturing. Mesoproterozoic rifting initiated the fragmentation of Columbia between 1.5 and 1.35 Ga, as witnessed by the intrusion of alkaline complexes along the cratonic margins and the development of huge sedimentary basins that later would become part of mobile belt. The Mesoproterozoic rifts were closed between 1.1 and 1.0 Ga by compressive orogeny reflecting the assembly of the Rodinia supercontinent. This second suturing involved the production of voluminous collision-related S-type granites and a second episode of granulite-facies metamorphism at ~ 1.0 Ga. The Chilka Lake anorthosite (750 Ma) along the eastern margin of the EGB may indicate the onset of Rodinia fragmentation. Lithological, geochemical and geochronological evidences document that the first episode of collision (~ 1.6 Ga) in the Eastern Ghats Belt was of Pacific-type whereas the second Grenvillian-age collision was of Alpine-type.