Detrital zircon U-Pb ages of Proterozoic and Cretaceous sandstones of Narmada region in Central India: Implications for provenance and the closure age of the Vindhyan Basin

Abstract

This study presents detrital zircon U-Pb ages of the Upper Bhander Sandstones from the Bhopal inlier, and the overlying Cretaceous sandstones from Jabalpur, Central India. These data are combined with existing palaeobiological evidence to address the issue of lack of convergence between geochronology and biochronology of the Upper Vindhyan succession in central India. The age-spectra of Upper Bhander Sandstone show the dominance of detrital zircon population between 1500-1900 Ma, a subordinate cluster of 2400-2600 Ma, and a single youngest zircon grain of ~770 Ma. These detrital zircon ages correlate with the timing of granite magmatism in Bundelkhand, Aravalli and Central Indian Tectonic Zone (CITZ), implying their derivation from these terranes. The finding of a single zircon of 770 + 12 Ma, supports the premise that Vindhyan deposition extended in to the late Tonian. Cretaceous sandstones of the Jabalpur and Lameta Formations contain zircon grains of ~550 Ma and ~700-800 Ma age. Except for the evidence from this youngest Vindhyan sedimentary sequence, no rocks of Late Neoproterozoic-Early Cambrian age have so far been reported from Central India, which can be correlated with these zircon ages. Comparable age-spectra of the Upper Bhander and the Cretaceous sandstones indicates that the proximal Vindhyan sandstones could have supplied detritus to these younger sandstones. These Cretaceous sandstones also constitute a window to understand the geology of the pre-Cretaceous eroded terrain, and support the premise that the Vindhyan sedimentation did not terminate at 1000 Ma.