A Ca. 2.25 Ga mafic dyke swarm discovered in the Bastar craton, Central India: Implications for a widespread plume-generated large Igneous Province (LIP) in the Indian shield

Abstract

A precise U–Pb baddeleyite age (2251 ± 4 Ma) has been obtained for an ENE-trending dyke exposed near the Chhura region of the Bastar craton, and additional dykes of similar trend are also reported from other parts of the northern Bastar craton such as in the Dongergarh and Pakhanjore areas. We propose a new widespread ENE-trending ca. 2.25 Ga Chhura mafic dyke swarm in the Bastar craton, which represents a continuation of the NE- to ENE-trending ca. 2.26 Ga Kaptipada swarm in the Singhbhum craton. The adjoining Dharwar craton also hosts ca. 2.26–2.25 Ga magmatism, the N- to NNE-trending Ippaguda-Dhiburahalli dyke swarm. A geochemical match between the ca. 2.25 Ga Chhura, the ca. 2.26–2.25 Ga Ippaguda-Dhiburahalli, and most samples of the ca. 2.26 Ga Kaptipada swarms corroborates a genetic link. Together these mafic dykes in Bastar, Singhbhum and Dharwar cratons, define the ca. 2.26–2.25 Ga Ippaguda (-Dhiburahalli-Chhura-Kaptipada) LIP. The relative post-2.25 Ga rotations between the three cratons would allow two alternative locations for the plume centre either at the eastern end of the Kaptipada swarm in the Singhbhum craton or at the south end of the Ippaguda-Dhiburahalli swarm in the Dharwar craton. Alternatively, convergence of the Churra, Kaptipada and Ippaguda-Dhiburahalli sub-swarms could suggest a plume centre location in the Godavari rift, between the Bastar and Dharwar cratons. Magmatic events of approximately this 2.26–2.25 Ga age are known from other parts of the globe including East Antarctica, and Kaapvaal and Zimbabwe cratons.