Please use this identifier to cite or link to this item:
Scopus Web of Science® Altmetric
Type: Journal article
Title: Garnet pyroxenite from Nilgiri Block, southern India: vestiges of a Neoarchean volcanic arc
Author: Samuel, V.
Kwon, S.
Santosh, M.
Sajeev, K.
Citation: Lithos, 2018; 310-311:120-135
Publisher: Elsevier
Issue Date: 2018
ISSN: 0024-4937
Statement of
Vinod O. Samuel, Sanghoon Kwon, M. Santosh, K. Sajeev
Abstract: Southern peninsular India preserves records of Late Neoarchean−Early Paleoproterozoic continental building and cratonization. A transect from the Paleoarchean Dharwar Craton to the Neoarchean arc magmatic complex in the Nilgiri Block across the intervening Moyar Suture Zone reveals an arc-accretionary complex composed of banded iron formation (BIF), amphibolite, metatuff, garnet-kyanite schist, metagabbro, pyroxenite and charnockite. Here we investigate the petrology, geochronology and petrogenesis of the pyroxenite and garnet-clinopyroxenite. The pyroxenite is mainly composed of orthopyroxene and clinopyroxene with local domains/pockets enriched in a clinopyroxene-garnet assemblage. Thermobarometric calculations and phase equilibria modeling suggest that the orthopyroxene- and clinopyroxene-rich domains formed at 900–1000 °C, 1−1.2 GPa whereas the garnet- and clinopyroxene-rich domains record higher pressure of about 1.8−2 GPa at similar temperature conditions (900−1000 °C). Zircon U–Pb SHRIMP dating show weighted mean ²⁰⁷Pb–²⁰⁶Pb age of 2532 ± 22 Ma, with metamorphic overgrowth at 2520 ± 27 Ma and 2478 ± 27 Ma. We propose a tectonic model involving decoupling and break-off of the oceanic plate along the southern flanks of the Dharwar Craton, which initiated oceanic plate subduction. Slab melting eventually built the Nilgiri volcanic arc on top of the over-riding plate along the flanks of the Dharwar Craton. Our study supports an active plate tectonic regime at the end of the Archean Era, aiding in the growth of paleo-continents and their assembly into stable cratons.
Keywords: Garnet pyroxenite; arc magmatism; metamorphic phase equilibria; Neoarchean-Paleoproterozoic; Southern India
Rights: © 2018 Elsevier B.V. All rights reserved.
RMID: 0030086593
DOI: 10.1016/j.lithos.2018.04.009
Appears in Collections:Geology & Geophysics publications

Files in This Item:
There are no files associated with this item.

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.