Zircon U-Pb ages and Hf isotopic systematics of charnockite gneisses from the Ediacaran-Cambrian high-grade metamorphic terranes, southern India: constraints on crust formation, recycling, and gondwana correlations
Date
2017
Authors
Vijaya Kumar, T.
Bhaskar Rao, Y.
Plavsa, D.
Collins, A.
Tomson, J.
Vijaya Gopal, B.
Babu, E.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Geological Society of America Bulletin, 2017; 129(5-6):625-648
Statement of Responsibility
T. Vijaya Kumar, Y.J. Bhaskar Rao, Diana Plavsa, Alan S. Collins, J.K. Tomson, B. Vijaya Gopal, and E.V.S.S.K. Babu
Conference Name
DOI
Abstract
The Southern Granulite terrane, southern India, comprises a vast exposure of deep crust and forms a key region in the reconstruction of the Gondwana supercontinent. An E-W–trending crustal-scale shear zone, the Palghat-Cauvery suture zone system, which formed during the late Neoproterozoic–Cambrian (0.75–0.50 Ga), marks a prominent terrane boundary separating terranes with a predominantly late Neoarchean (ca. 2.5 Ga) regional granulite metamorphism to the north from those with an Ediacaran–Cambrian (0.63–0.50 Ga) regional granulite metamorphism to the south. Focusing on the younger granulite metamorphic domains, we present here new zircon U-Pb ages and Hf isotopic compositions for 11 charnockite orthogneisses from the Madurai, Trivandrum, and Nagercoil blocks and contribute to the resolution of the age of their magmatic protoliths. This study shows that the charnockite orthogneisses south of the Palghat-Cauvery suture zone relate to a minimum of four distinct episodes of felsic magmatism centered at: ca. 2.62–2.46 Ga, ca. 2.05–1.84 Ga, ca. 1.0–0.9 Ga, and ca. 0.80–0.76 Ga, pertaining to the Siderian, Orosirian, and Tonian Periods. Hafnium isotope analyses of zircon grains from the charnockite gneisses suggest that the protoliths of the ca. 2.05–1.98 Ga gneisses from the Trivandrum and Nagercoil blocks and the ca. 1.0–0.9 Ga gneisses along the southeastern Madurai block involved a significant juvenile magma component, while the protoliths of charnockite gneisses elsewhere in the Madurai block formed mainly through recycling of older crust up to ca. 3.2 Ga. A regional granulite-facies metamorphic imprint during the Ediacaran–Cambrian marked an advanced stage in the amalgamation of the Madurai, Trivandrum, and Nagercoil blocks into the East African orogen and its collision with the Dharwar craton.
School/Discipline
Dissertation Note
Provenance
Description
Published online 22 December 2016.
Access Status
Rights
© 2016 Geological Society of America