A Tidal Island Model for Carbonate Sedimentation: Karondia Limestone of Cretaceous Narmada Basin, India

The Cretaceous sedimentary sequence of Narmada basin comprise a lower clastic formation (Nimar Sandstone) and an upper carbonate sequence (Karondia Limestone). The depositional model of limestones was reconstructed by identifying 8 microfacies which were regrouped into 5 facies associations. The carbonate sequence of the study area was interpreted to be deposited on a ramp without a striking break in the slope of the ramp and where shelf margin was not developed. The vertical arrangement of facies of Karondia Limestone forms a shallowing upward sequence. It shows much lateral and vertical variation which can be attributed to deposition on a platform dotted by a mosaic of exposed banks or island separated by subtidal areas with the whole complex shifting both laterally and vertically in response to hydrodynamic conditions through time.