Crustal evolution of the amphibolite- to granulite-facies transition zone in the eastern Dharwar Craton, southern India: insight from petrological modelling, zircon U–Pb geochronology and Hf isotopes

Bidyananda Maibam*, Richard M. Palin, Axel Gerdes, Richard W. White, Jasper Berndt, Stephen Foley, Jiten N. Goswami

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Integrated petrological, geochemical, isotopic and thermobarometric study of metasedimentary rocks from the amphibolite- to granulite-facies transition zone of the Eastern Dharwar Craton (EDC), South India, has provided new insight into the evolution of the lower continental crust in this region. Phase equilibrium modelling of metapelites and metagreywackes suggests that they reached peak metamorphism at ~800–850°C and 6–7 kbar (corresponding to a paleodepth of ~20 km), with minor retrograde change occurring at ~700°C and 3–5 kbar during exhumation. U–Pb ages of conventionally separated zircon from metapelite samples range from 2.5 to 3.4 Ga, whereas garnet-hosted zircons yield younger ages of 2.5–2.7 Ga. Zircon Th/U ratios and Hf isotopes reveal several significant pulses of zircon growth at 3.0, 2.95 and 2.7 Ga. Hf isotope data suggest the evolution of juvenile magma at around 3.2 Ga, while Hf model ages show that the crust building process also involved the recycling of pre-existing Mesoarchean crust. Our study confirms the presence of a Paleoarchean component in the EDC lower crust, as well as older metamorphic events in the terrain and the gradational distribution of the metamorphic rocks.

Original languageEnglish
JournalGeological Journal
Early online date12 Dec 2023
DOIs
Publication statusE-pub ahead of print - 12 Dec 2023

Bibliographical note

Funding Information:
Bidyananda Maibam initiated the research at the University of Mainz during a BOYSCAST Fellowship awarded by the Department of Science and Technology, Government of India, and continued during subsequent visits at Mainz (supported by the Geocycles Research Centre) and Bonn (INSA‐DFG Exchange Program). Two anonymous reviewers for their insightful comments and Associate Editor, Dr. C. Manikyamba for suggestions. Sample processing equipment was procured under the FIST program of the Department of Science and Technology, Government of India. The studied samples were collected during BM's post‐doctoral tenure at PRL, Ahmedabad, in collaboration with JNG and grateful to Dr. R. Srinivasan for valuable discussions during the initiation of the work and Dr. S. Jayaram for the field study assistance. Thanks to Beate Schmitte for help and assistance in the Münster LA‐ICP‐MS laboratory. This is FIERCE contribution No. 148.

Publisher Copyright:
© 2023 John Wiley & Sons Ltd.

Keywords

  • Dharwar Craton
  • juvenile magma
  • metapelite
  • petrological modelling
  • U–Pb geochronology
  • zircon Lu–Hf isotope

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