Paleo-Mesoproterozoic Rifting Along the Margins of Archean Bundelkhand Craton North-Central India: Timing the Event from U–Pb SHRIMP Zircon Data and Their Geodynamic Implications

Abstract

In this article, novel geochronological (U–Pb SHRIMP) and geochemical data are presented from the lowermost sandstone unit (Par formation), basement granites of Gwalior Basin and sandstones from the Bhopal Basin, located along margins of the Archaean Bundelkhand Craton. The geochemical variation diagrams imply that sandstone units in the Gwalior and Bhopal Basins were deposited in rift-induced passive margin tectonic settings. In contrast to the magmatic features that are preserved in the zircons of granite of the Gwalior Basins, detrital zircons from sandstones of both basins are fragmentary and polymodal in size. The magmatic zircon grains from the basement granites yield a 207Pb/206Pb concordant age of 2538 ± 2 Ma. A group of detrital zircons from the sandstone of the Gwalior Basin with concentric magmatic zonation yield a weighted mean average age of 2564 ± 24 Ma. The detrital zircons from Gwalior Basin exhibit a patchy U-Th distribution overgrowing the magmatic zonation yield average age of 2044 ± 2 Ma. The detrital zircons from the Bhopal basin yield three distinct concordant ages of 2511 ± 5, 1694 ± 6, and 1355±9 Ma. The presence of ~2540 Ma concordant zircon population with concentric zonation in the sandstone of Bhopal Basin suggests their derivation from the granite of similar age. Therefore, an extension of Bundelkhand Craton granite below the Bhopal Basin is suggested. The 2500 Ma ages from the Gwalior granites are linked to global magmatic activity leading to the stabilization of extended Ur at ~2500 Ma. The 2048 and 1355 Ma ages from the Gwalior and Bhopal Basins, respectively, are concluded as the maximum depositional age (MDA) of the lowermost stratigraphic units within the basins. The MDAs are concluded to be the timings of passive margin basin formations along margins of the Bundelkhand Craton during extended Ur and Nuna or Columbia disintegration, respectively, during plume-driven tectonics.