U-Pb geochronology of rutiles from Southern granulite Terrane, India: Implications for the cooling and exhumation of East Gondwanan terranes

Abstract

The Precambrian Southern Granulite Terrane of south India figures prominently in the East African collisional orogen, linked to the assembly of the East Gondwana supercontinent along with Sri Lanka, Madagascar, Antarctica, and Africa. While the timing of this collision and associated magmatic-metamorphic processes are well constrained, the mechanisms governing the cooling and exhumation of these terranes remain uncertain. This study focuses on U-Pb rutile ages derived from granulites in the Southern Granulite Terrane and attempts to extract the cooling history of the terrane. Our new U-Pb rutile ages cluster between 422 to 458 Ma, postdating regional metamorphism and indicating an extended cooling period of ∼ 35 Ma whereas trace element signatures suggest their formation during granulite facies metamorphism with temperatures reaching up to ultrahigh-temperature conditions. Calculated cooling rates using these rutile U-Pb ages range between 2–6 °C/Ma similar to the cooling rate of ≤ 7 °C/Ma from other East Gondwanan terranes. Based on these results it is proposed that the coeval exhumation of these terranes was assisted by surface erosion after the final assembly of the East Gondwana supercontinent.