Palaeoproterozoic ancestry of Pan-African high-grade granitoids in southernmost India: Implications for Gondwana reconstructions

摘要: Abstract SHRIMP dating of magmatic zircons from granitoid gneisses and charnockites the Trivandrum Nagercoil Blocks in granulite terrane southernmost India yielded well-defined protolith emplacement ages between 1765 ca. 2100 Ma also document variable recrystallization and/or lead-loss during late Neoproterozoic Pan-African event at around 540 Ma. Hf-in-zircon whole rock Nd isotopic data suggest that host rocks were derived mixed crustal sources, Hf–Nd model vary 2.2 2.8 Ga. A gabbroic dyke, emplaced into a charnockite deformed together with it, only contained metamorphic zircon whose mean age 542.3 ± 4.0 Ma reflects peak granulite–facies metamorphism high-grade event. The Sm–Nd whole-rock system several samples dated this study was significantly disturbed metamorphism, most likely due to CO 2 -rich fluid phase. Whole-rock are consistently older than zircon-derived Hf ages. reinterpreted as single tectono-metamorphic predominantly consisting Palaeoproterozoic granitoids interlayered supracrustal must be 2100 Ma. Ductile deformation, migmatization anatexis have obliterated original relationships. These blocks probably their counterpart Highland Complex neighbouring Sri Lanka southern Madagascar. We speculate Indian khondalites may counterparts khondalite belt North China Craton.