Zircon ages and Hf isotopic systematics reveal vestiges of Mesoproterozoic to Archaean crust within the late Neoproterozoic-Cambrian high-grade terrain of southernmost India

► Two granulites in the Trivandrum Block have Proterozoic protolith ages. ► Zircon Hf isotopic data reveal melting of Archaean crustal sources. ► Crustal-melt granites cannot be used to reconstruct tectonic settings. ► The Trivandrum and Madurai blocks are similar to the Highland and Wanni Complexes in Sri Lanka.