Spatio-temporal patterns of environmental changes in Late Cretaceous sequences of Central India

Abstract

Late Cretaceous strate of Central India-the Bagh and Lameta Beds/Intertrappean Beds are patchily distributed as thin sedimentary sequences in the rift zones of Central India. These strata record the spatio-temporal variations of Late Cretaceous environments in an Indian lithosphere influenced by rifting, plume activity (Kerguelen and Reunion) and continental flood basalt volcanism. Analysis of depositional environments of these strata reveal that an epicontinental seaway advanced from the west during the Turonian (?) and inundated areas a few hundred kilometers inland in the Lower, Narmada Basin. Earlier phases of rifting related sedimentation included estuarine facies (Nimar Group) in the Lower Narmada Basin and fluvial channel facies (Jabalpur Group) in the upper parts of the basin. Fluvial/lacustrine/palustrine and sheetwash deposits constitute the infra- and intertrappean sequences which are broadly coveal with the Maastrichtian Deccan lava flows. Surface uplift, possibly plume related, caused withdrawal of the, sea from the Lower Narmada Basin; and raised the land surfaces in the upper parts of the basin. This led to the occurrence of widespread subaerial exposure conditions as revealed by the regionally persistent dinosaur egg-shell-bearing Lower Limestone (Lameta Beds)-a palustrine-pedogenic facies. In some regions of the central Indian lithosphere the Infratrappean Lameta Beds are made up of alluvial-lacustral facies. Such areas possibly represent those parts of the Indian lithosphere effected by surface uplift and fracturing/faulting. Faulting-related relief produced adequate topographic differentiation to maintain alluvial-lacustrine systems.