Epicontinental Permian-Cretaceous seaways in central India: The debate for the Narmada versus Godavari rifts for the Cretaceous-Tertiary incursion

Abstract This study presents an overview of Mesozoic transgressions that influenced the palaeogeography of central India, and offers an analysis of the existing evidence for the interpretation of the depositional record of infra- and inter-trappean sequences. These data are then used to understand the respective palaeogeographic settings of the Narmada and the Godavari master valleys, leading to a reappraisal of the paths suggested thus far for a Cretaceous-Tertiary (K-T) seaway. Major rift related discontinuities have been subjected to reactivation episodes during the Mesozoic. These tectonic events caused the initiation of several pericratonic basins. The riftogenic valley systems have been affected by transgressions from the western margin of India through the Narmada valley; and/or from the eastern margin through the Godavari valley. However, for the most part, these continent-scale valley systems have hosted mainly Mesozoic fluviatile and lacustrine sediment successions. Besides, a marine incursion from the west in the lower reaches of Narmada Valley is widely recognised on the basis of the Late Cretaceous Bagh Beds. Additionally, the Maastrichtian palaeogeography of these valley systems of central India have been strongly influenced by the uplift resulting from the thermo-magmatic flux associated with the Deccan volcanism. This resulted in major topographic readjustments within the Godavari and Narmada-Tapti palaeovalleys resulting in turn, in major basinal depressions as revealed from the reconstruction of the palaeo-digital elevation model. Significantly removed from the eastern and western coastal margins of India, isolated occurrences of marine biota such as foraminifera, marine algae and palm fossils have been found in infra- and inter-trappean (Maastrichtian and Danian) sequences of central India. Their presence in these inland basins is enigmatic and three hypotheses have been proposed to explain the presence of marine environments in these basins: (a) “Trans Deccan Strait”, connecting both the margins of India through pre-existing rift systems; (b) an ~800 km long seaway through the Narmada valley; and (c) a marine incursion through the Godavari valley. This palaeogeographic analysis supports a marine incursion through the Godavari rift and presents arguments against the other two.