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Petrology and Sr-Nd isotope systematics of the Ahobil kimberlite (Pipe-16) from the Wajrakarur field, Eastern Dharwar craton, southern India

Sharma, Abhinay and Kumar, Alok and Pankaj, Praveer and Pandit, Dinesh and Chakrabarti, Ramananda and Rao, N. V. Chalapathi (2019) Petrology and Sr-Nd isotope systematics of the Ahobil kimberlite (Pipe-16) from the Wajrakarur field, Eastern Dharwar craton, southern India. In: GEOSCIENCE FRONTIERS, 10 (3, SI). pp. 1167-1186.

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Official URL: https://doi.org/ 10.1016/j.gsf.2018.08.004

Abstract

Detailed mineralogical, bulk-rock geochemical and Sr-Nd isotopic data for the recently discovered Ahobil kimberlite (Pipe-16) from the Wajrakarur kimberlite field (WKF), Eastern Dharwar craton (EDC), southern India, are presented. Two generations of compositionally distinct olivine, Ti-poor phlogopite showing orangeitic evolutionary trends, spinel displaying magmatic trend-1, abundant perovskite, Tirich hydrogarnet, calcite and serpentine are the various mineral constituents. On the basis of (i) liquidus mineral composition, (ii) bulk-rock chemistry, and (iii) Sr-Nd isotopic composition, we show that Ahobil kimberlite shares several characteristic features of archetypal kimberlites than orangeites and lamproites. Geochemical modelling indicate Ahobil kimberlite magma derivation from small-degree melting of a carbonated peridotite source having higher Gd/Yb and lower La/Sm in contrast to those of orangeites from the Eastern Dharwar and Bastar cratons of Indian shield. The T-DM Nd model age (similar to 2.0 Ga) of the Ahobil kimberlite is (i) significantly older than those (1.5-1.3 Ga) reported for Wajrakarur and Narayanpet kimberlites of EDC, (ii) indistinguishable from those of the Mesoproterozoic EDC lamproites, and (iii) strikingly coincides with the timing of the amalgamation of the Columbia supercontinent. High bulk-rock Fe-Ti contents and wide variation in oxygen fugacity fO(2), as inferred from perovskite oxy-barometry, suggest non-prospective nature of the Ahobil kimberlite for diamond. (C) 2018, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to CHINA UNIV GEOSCIENCES
Keywords: Petrology; Isotopes; Kimberlite; Wajrakarur; Dharwar craton; India
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Depositing User: Ms Ranganayaki RS
Date Deposited: 21 May 2019 12:54
Last Modified: 21 May 2019 12:54
URI: http://eprints.iisc.ac.in/id/eprint/62570

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