Ichnology of the Late Cretaceous to Early Miocene Beni Ider and Talaa Lakrah turbidite successions of the Maghrebian Flysch Basin (Northern Rif, Morocco)

Abstract Ichnological studies in deep-marine successions are of great use for detailing the evolution of these sedimentary environments, as well as highlighting the changes in ambient conditions. In order to investigate these aspects, the deep-marine Maghrebian Flysch Basin of Northern Morocco was chosen for study. Within this basin, two sedimentary successions – the Beni Ider and Tala Lakrah units, comprising calcareous and siliciclastic turbidite sediments and ranging in age from Late Cretaceous to Early Miocene, were examined in detail. An ichnoassemblage (31 ichnogenera, 41 ichnospecies), including 9 graphoglyptid ichnogenera, was recognised, with the ichnoassemblages belonging to the Nereites ichnofacies. Pre- and post-depositional ichnofossils were present in equal amounts, with ichnodiversity being higher in Eocene times. Comparison and correlation of the ichnological data from Morocco (this study) with data from Spain indicated that the main influences on trace fossil distribution within the successions were broadly similar. Environmental factors, such as substrate, oxygen and nutrient contents, as well as the ambient hydrodynamic regime and the frequency and intensity of turbiditic events, all played an important role. However, the relative importance of these factors varied both spatially as well as temporally within the different parts of the Maghrebian Flysch Basin. Temporal variations were related both to changes in (orogenically-influenced) basin and lobe evolution, as well as changes in global oceanographic and climatic conditions at the Eocene–Oligocene transition.