U-Pb zircon and titanite ages from granulites of the Koraput area – Evidence for Columbia, Rodinia and Gondwana from the Eastern Ghats Province, India

Abstract

The Eastern Ghats Province (EGP) of India, characterized by ∼1 Ga granulite metamorphism (M1), collided with the Archaean Indian craton in either Grenvillian (∼1 Ga) or Pan-African (∼0.6–0.5 Ga) time. At ∼850 Ma, the Koraput Alkaline Complex (KAC) intruded into M1 EGP granulites, and was metamorphosed during a second granulite event (M2) in the EGP. U-Pb zircon dates from gneisses in Koraput yield magmatic ages ∼1500 Ma, with overgrowths at 1100–900 Ma and 800–700 Ma. Cratonic zircons from the EGP contact zone have Archaean 2.8–2.6 Ga cores with overgrowths at ∼700 Ma. Titanites from a calc-silicate gneiss within the EGP define a U-Pb isochron around 700 Ma, whereas titanites from nepheline syenites within the KAC yielded a range of dates from ∼622 to 520 Ma. The c. 1500 Ma age in the EGP either implies Columbia break-up or proximity to a Columbia margin. The ∼700 Ma age is interpreted as the age of M2 granulite metamorphism that followed intracontinental thrusting of the EGP over ∼2.8 Ga granulites of the Jeypore Province. The ∼520 Ma titanite ages are correlated with final juxtaposition of the EGP-Jeypore Province amalgam with the Indian craton during Gondwana formation.