A Review of the Cretaceous Ichnology of Tethys-Related Basins in India: New Record From the Bagh Group

Abstract

The Narmada Basin in west-central India forms the northern part of the Central Indian Tectonic Zone (CITZ). The Cretaceous Bagh Group rocks of the Western Lower Narmada Valley (WLNV) succession was studied for sedimentary facies analysis and ichnology. Textural and mineralogical characteristics along with primary and secondary sedimentary structures revealed 11 lithofacies, of which the calcareous sandstone, fine-grained sandstone-siltstone-shale and sandy/silty allochemic limestone lithofacies are highly bioturbated. WLNV contains a well-preserved, less diverse, and relatively abundant ichnofauna; a total of 24 ichnospecies belonging to 15 ichnogenera with pseudotrace fossils are identified and described. The trace fossils belong to the Skolithos, Cruziana and Glossifungites Ichnofacies. The Skolithos Ichnofacies suggest an upper shoreface environment with moderate-to-high energy conditions and shifting substrate; the Cruziana Ichnofacies suggest a lower shoreface environment with low-to-moderate sedimentation rates and energy conditions and the Glossifungites Ichnofacies suggest dewatering of sediments and a slow rate of sedimentation. Early ichnological studies in the different Tethys-related Cretaceous basins of the Indian subcontinent (Eastern Lower Narmada Valley, Kachchh, Cauvery, Jaisalmer, Barmer and Saurashtra) primarily focused on identifying the trace fossils, describing the new species and interpreting them in relation to trace producers and depositional environment. However, many of the ichnogenera and ichnospecies established from these basins need special attention because they either have been described as invalid, revised or assigned an unclear taxonomic status. The Cretaceous trace fossils reported to date from these basins are compiled along with their paleoenvironmental interpretation. The study also discusses the present status of the ichnogenera and ichnospecies names of the trace fossils reported to date from these basins. These data can be further used to enhance our understanding of how paleoenvironmental conditions control the distribution of trace-making communities across space and time.