Mesoproterozoic 40Ar/39Ar age and Sr-Nd isotopic geochemistry of calc-alkaline lamprophyre from the Mudigubba area, Eastern Dharwar Craton, India

Pandey, A and Chalapathi Rao, NV and Chakrabarti, R (2020) Mesoproterozoic 40Ar/39Ar age and Sr-Nd isotopic geochemistry of calc-alkaline lamprophyre from the Mudigubba area, Eastern Dharwar Craton, India. In: Current Science, 119 (7). pp. 1142-1148.

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Abstract

We report a 40Ar/39Ar Mesoproterozoic radiometric age for a calc-alkaline lamprophyre dyke from the Mudigubba area towards the western margin of the Cuddapah Basin, Eastern Dharwar Craton (EDC), Southern India. Amphibole phenocryst separates from this lamprophyre yielded a plateau age of 1169 ± 8 Ma (2�), which is almost 50 million years older than the majority of radiometric dates available for the Wajra-karur field kimberlites which are proximal to this dyke. Bulk-rock Sr-Nd isotopic analyses of the Mudi-gubba lamprophyre dykes (εNd(t) between -13.3 and -12.4) reveal their derivation from an old, enriched, continental lithospheric mantle unlike the kimberlites (bulk-rock and perovskite in situ εNd(t) between -0.77 and +7.93), which originated either from a chondritic or depleted mantle source. This study provides further evidence for emplacement of compositionally distinct, mantle-derived Mesoproterozoic alkaline magmas in the EDC and highlights the extremely heterogeneous character of the lithospheric mantle beneath this craton. © 2020. All rights reserved.

Item Type:	Journal Article
Publication:	Current Science
Publisher:	Indian Academy of Sciences
Additional Information:	The copyright for this article belongs to Indian Academy of Sciences
Department/Centre:	Division of Mechanical Sciences > Centre for Earth Sciences
Date Deposited:	16 Sep 2021 08:41
Last Modified:	16 Sep 2021 08:41
URI:	http://eprints.iisc.ac.in/id/eprint/67363

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