Zircon-monazite geochronology and P-T evolution of the Sargur Greenstone Belt: Implications for the end-Archean tectonics of the Dharwar Craton in southern India

Zhao, Y and Zhai, M and Zhang, C and Sun, Y and Gou, L and Lu, J and Sajeev, K and George, PM and Ao, W and Hu, Y and Xu, X (2021) Zircon-monazite geochronology and P-T evolution of the Sargur Greenstone Belt: Implications for the end-Archean tectonics of the Dharwar Craton in southern India. In: Precambrian Research, 364 .

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Abstract

We report petrological and geochronological data for metamafic volcanics and metasediments from the Sargur Greenstone Belt, Western Dharwar Craton (WDC), southern India and discuss the end-Archean metamorphic P�T conditions of the Sargur Greenstone Belt, as well as geotectonic implications of the end-Archean metamorphism in the WDC. The LA-ICP MS zircon U-Pb dating yields a metamorphic age of 2500 ± 20 Ma for the garnet-bearing amphibolite. The garnet-staurolite-kyanite mica schist sample has metamorphic zircon and monazite U-Pb ages of 2443 ± 7 Ma and 2468 ± 10 Ma, respectively, consistent with metamorphic zircon U-Pb ages of 2459 ± 17 Ma and 2455 ± 18 Ma yield by the amphibole-garnet schist samples. The peak mineral assemblage of the garnet-bearing amphibolite is garnet + clinopyroxene + amphibole + plagioclase + quartz + rutile + ilmenite, and that of the metapelitic schist is garnet + staurolite + kyanite + biotite + muscovite + quartz + plagioclase. Phase equilibrium modelling, together with geothermobarometers yield P�T conditions of 7.9�8.9 kbar/681�769 °C and 7.5�9.3 kbar/683�694 °C for the garnet-bearing amphibolite and garnet-staurolite-kyanite mica schist, respectively, corresponding to a medium geothermal gradient of 20�25 °C/km. These data indicate that the Sargur Greenstone Belt has experienced a typical Barrovian-type (amphibolite-facies) metamorphism at ca. 2.50�2.44 Ga. Combined with the previous studies, it is suggested that the Sargur Greenstone Belt was most likely to be formed during 3.35�3.12 Ga and was reworked through four episodes of magmatic-metamorphic events occurred at ca. 3.1 Ga, ca. 3.0 Ga, ca. 2.8�2.6 Ga and ca. 2.5�2.4 Ga. The prominent ca. 2.5�2.4 Ga regional metamorphism is the last stage of the Neoarchean tectono-thermal event in the WDC and thus most possibly indicate accretion-collision of different Archean blocks at ca. 2.5�2.4 Ga and lead to the final cratonization (stabilization) of the whole Dharwar Craton. © 2021 Elsevier B.V.

Item Type:	Journal Article
Publication:	Precambrian Research
Publisher:	Elsevier B.V.
Additional Information:	The copyright for this article belongs to Elsevier B.V.
Department/Centre:	Division of Mechanical Sciences > Centre for Earth Sciences
Date Deposited:	03 Dec 2021 07:07
Last Modified:	03 Dec 2021 07:07
URI:	http://eprints.iisc.ac.in/id/eprint/70136

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