Pb-Pb baddeleyite ages of mafic dykes from the Western Dharwar Craton, Southern India: a window into 2.21–2.18 Ga global mafic magmatism

Abstract

Paleoproterozoic mafic magmatism in the Dharwar Craton (DC) is evident by ubiquitous dykes of varied orientations and emplacement ages. Eight distinct mafic dyke events have been identified in the Eastern Dharwar Craton (EDC), while studies in the Western Dharwar Craton (WDC) were restricted to a previously dated Dandeli dyke. Precise baddeleyite TE-TIMS Pb-Pb ages for five mafic dykes across the WDC reveal emplacement ages of 2212.3 ± 0.8 Ma, 2212.9 ± 0.4 Ma, 2208.1 ± 0.8 Ma, 2205.2 ± 0.8 Ma for NW-SE to NNW-SSE trending dykes and 1957.3 ± 0.7 Ma for ENE-WSW dyke. The ca. 1.96 Ga Mundargi dyke establishes a new episode of mafic magmatism in the DC, whereas ca. 2.21 Ga mafic dykes suggests widespread mafic magmatism across the DC. The collective trend of ca. 2.21–2.20 Ga radiating dykes vary from N100°E in EDC to N165°E in WDC, converging towards the north-western margin of DC (fanning angle ≃65°), where a mantle plume appears to be located. It is postulated that ca. 2.18 Ga Mahbubnagar-Dandeli dyke swarm of the DC also originated from a similar plume source, but as a distinct pulse within a time span of 35–40 Myr. Present study depicts barcode of the WDC and represents an epitome of correlations with the EDC, Superior, Slave and Greenland Cratons. Widespread ca. 2.21–2.18 Ga LIP event indicates that these cratons were located at proximity and suggests breakup of supercraton (Sclavia/Superia). The single ≃1.96 Ga Mundargi dyke is coeval with the dykes and sills of Karelia, North China and North Atlantic Cratons.