Constraints on the Timing of Pan‐African Granulite‐Facies Metamorphism in the Kerala Khondalite Belt of Southern India: SHRIMP Mineral Ages and Nd Isotopic Systematics

Abstract

The supracrustal Kerala Khondalite Belt (KKB; southern India) constitutes an important but little understood terrain in the evolution of East Gondwana. Here we report SHRIMP U‐Pb zircon and titanite ages for a suite of metasedimentary rocks from the KKB. Metamorphic ages at $$530.2\pm 4.4$$ and $$525\pm 4.5$$ Ma were obtained from metapelitic and metapsammitic migmatites, respectively. These ages are interpreted to date peak metamorphism because both rock types have extensively melted under granulite‐facies conditions. A similar age ($$520\pm 4.7$$ Ma) was obtained from titanite from a granulite‐facies calc‐silicate rock. These ages are within error of SHRIMP ages for granulite‐facies assemblages in Lützow‐Holm Bay, East Antarctica, the Highland and Wanni Complexes of Sri Lanka, and Southern Madagascar. We propose that this timing reflects a short span (∼10 m.yr.) of high‐temperature granulite‐facies metamorphism and concomitant widespread migmatization that marks the final stage of collision between East and West Gondwana.