U–Pb zircon chronology of the Pangidi–Kondapalle layered intrusion, Eastern Ghats belt, India: Constraints on Mesoproterozoic arc magmatism in a convergent margin setting

Abstract

The Pangidi–Kondapalle layered intrusion is emplaced within high-grade supracrustal rocks in the southern sector of the Eastern Ghats Granulite Belt proximal to the south-eastern periphery of the Indian plate. This layered complex consists mainly of anorthosites and gabbronorites with pyroxenite cumulates containing orthopyroxenites and chromitites in a regressive intrusive sequence. Here we report laser ablation ICP-MS data and REE geochemistry of zircons from three co-spatial anorthositic bodies in this complex. Our results show mean 207Pb/206Pb ages of 1634±18Ma (MSWD=0.55) for the anorthosite from Pangidi. Two anorthosite samples from Kondapalle yield mean207Pb/206Pb ages of 1628±36Ma (MSWD=0.54) and 1693±110Ma (MSWD=5.5). The zircons from all the anorthosite samples show high REE contents, prominent HREE enrichment and a conspicuous positive Eu anomaly, suggesting a common melt source. The prominent Mesoproterozoic ages revealed from our U–Pb dating of zircons from these layered complexes suggest subduction-related magmatic underplating in a convergent margin setting associated with the amalgamation of the Columbia-derived fragments within the Neoproterozoic supercontinent.