Taphofacies from the lower Eocene Naredi Formation of Kutch Basin, western India, and their significance

The Cenozoic marine sedimentation in the Kutch Basin, western India, initiated with the Naredi Formation, a dominantly argillaceous unit interbedded with a foraminiferal limestone. While the formation has been studied from sedimentological, paleontological, and geochemical perspectives, taphonomy remains largely unexplored. This study presents a novel classification of sedimentary rocks based on the taphonomic characteristics of embedded fossils, with the focus on Larger Benthic Foraminifera and Mollusca. Six Taphofacies are identified using the following criteria: fragmentation, imbrication, diagenetic alteration, type of preservation and packing, distribution of sizes, bioturbation, and articulation. The taphofacies, along with a detailed study of the existing horizons, indicate a more intricate depositional picture of the Naredi Formation than previously recognized. Notably, five transient regressive phases are identified, four of which coincide with Taphofacies C, marked by evaporite presence and lagoonal restriction, challenging earlier interpretations of a single transgressive–regressive cycle. Taphonomic evidence also captures intra-horizon variability, including current-induced fragmentation in middle ramp deposits, microbial micritization of LBF tests, and soft-sediment deformation features. Overall, the integration of taphonomic, sedimentological, and paleontological data refines the lagoonal-to-open marine depositional model and highlights the utility of taphofacies analysis as a tool for reconstructing palaeoenvironmental and diagenetic histories.