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Long-lived mantle plume for the emplacement of Paleoproterozoic Dharwar-Bastar Large Igneous Province: Geochemical and Srsingle bondNd isotope constraints from mafic rocks of Dharwar craton, India.

The present study is based on geochemical and Sr, Nd isotopic studies for precisely dated mafic rocks (dykes/sills) of ~1.89 to ~1.86 Ga from different parts of the Dharwar craton, Southern India. These rocks are basaltic in composition with a sub-alkaline tholeiitic nature, originating from a shallower spinel lherzolitic mantle source. Mafic rocks of coeval ages are also present in Central India (Bastar craton) and Western Australia (Yilgarn craton). The geochemical and isotopic correlation among these three cratons indicates that the Dharwar and Bastar rocks were generated from the partial melting of the enriched subcontinental lithospheric mantle (SCLM), whereas the Yilgarn craton rocks originated from the depleted SCLMat ~1.89 Ga.

Based on the coeval ages, the orientation of dykes, geochemical and Sr, Nd isotopic results of the Indian dykes (Dharwar and Bastar cratons) and Australian dykes (Yilgarn craton) display different geochemical and isotopic characteristics, suggesting that these mafic events were generated in two different pulses from a common plume source within a span of 40 Ma(~1.89 Ga- ~1.85 Ga).

A hypothetical tectonic model shows the emplacement mechanism of mafic rocks at (a) ~1.89 Ga and (b) ~1.86-1.85 Ga in the Dharwar, Bastar and Yilgarn cratons, respectively. D: depleted; E: enriched; SCLM: subcontinental lithospheric mantle.

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