The North Saharian epicontinental carbonate platform at the Cenomanian/Turonian Boundary: OAE2 signature in shallow water (Akrabou Formation, Southeastern Morocco)

The Cenomanian/Turonian Boundary was a period of extreme environmental conditions, marked by hyperthermic climate, high sea-levels, and the Oceanic Anoxic Event 2 (OAE2). During this period, huge portions of the continental margins of North Africa were flooded, with the emplacement of an epicontinental carbonate platform known as North Saharian Platform. The Akrabou Formation in Southeastern Morocco provides an intriguing window into the dynamics of this shallow-marine carbonate system. This formation, up to 100 m thick, is dominated by low-energy, shallow-water facies with fine-grained wackestone/packstone rich in micrite and oligotypic assemblage of small benthic foraminifera, alternated to oyster-rich beds. A temporary shutdown of the benthic community and the deepening of the platform is testified by a fast and short transition to laminated lime-mudstones with planktonic foraminifera. After the return to shallow-water benthic-dominated facies, an increase in energy is observed before the emersion of the platform. Stable isotope analysis (δ13C) shows a positive excursion of +3‰ VPDB, aligning with global OAE2 signatures. Interestingly, the platform's maximum deepening occurs with a delay relative to the OAE2 isotopic peak, suggesting a complex interplay between global and local factors in platform evolution. Despite the stress induced by OAE2, evidenced by the temporary shift to deeper environments, the shallow benthic carbonate community demonstrated resilience, quickly re-establishing after the crisis. This study highlights the Akrabou Formation as a valuable archive of epicontinental carbonate platform dynamics during extreme environmental changes, offering insights into the interplay between global events and local responses in shallow-marine carbonate systems.