Precise Pb-Pb baddeleyite ages and petrogenesis of the NW-SE trending Paleoproterozoic mafic dyke swarm from the Bundelkhand craton, India: Implications to the enriched sub-continental lithospheric mantle

Abstract

Based on a similar structural trend, the NW-SE trending mafic dykes from the Bundelkhand craton were assigned an emplacement age of 1979 ± 8 Ma. Many geochemistry and paleomagnetic studies on these dykes have proposed the presence of more than one mafic dyke event within the NW-SE trending mafic dyke swarm. Still, until now, this suggestion was not supported by precise geochronology. This study presents TE-TIMS Pb-Pb baddeleyite ages of 2001.5±1.3 Ma, 2005.0±0.8 Ma, and 2004.5±0.7 Ma from the NW-SE trending dykes of Ajaygarh dyke swarm located towards the southeast margin of the Bundelkhand craton. The mean age of 2004.3±3.5 Ma is inferred as the emplacement age of these dykes. This dyke event is hitherto unknown and the oldest in the Bundelkhand craton. Further, we present the major and trace element geochemistry data on 34 samples from NW-SE trending dykes. These results suggest the presence of three geochemically distinct groups of dykes from NW-SE trending dykes. Further, the geochemical modeling of studied dykes suggests their derivation from subcontinental lithospheric mantle sources enriched by subduction-derived fluids at different depths and times. These dykes were emplaced as part of a sporadically spread global crustal extension event.