Evaluating the impact of the Toarcian oceanic anoxic event on neritic platform systems in NW-Africa

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The Early Toarcian is characterized by the occurrence of the first Mesozoic Oceanic Anoxic Event (OAE). This event (T-OAE) is associated with a very significant and complex perturbation of the Early Jurassic ocean-atmosphere system. In TOAE research, much attention has previously been paid to open oceanic settings as exposed in European outcrop belts. In contrast, field and geochemical evidence from non-European areas is surprisingly scarce. This forms a strong motivation for the project proposed here, aiming to assess the impact of Late Pliensbachian – Middle Toarcian palaeoenvironmental perturbations in the High Atlas Basin of Morocco. The High Atlas of Morocco offers an exceptional natural laboratory for this purpose. This as not only T-OAE-related basinal sediments but also their coeval platform equivalents are well exposed. In this region, the carbonate platform ecosystem is marked by repeated disruption and re-installation episodes, probably linked to environmental changes associated with the T-OAE. Rapid generation of accommodation space has lead to stratigraphically expanded basinal sections allowing for sampling in an extremely high temporal resolution across the Toarcian interval. Consequently, a high-resolution, multi-proxy approach (C, O and Sr isotopes, phosphorus, clay mineralogy) is proposed. Geochemical analyses are to be coupled with a detailed sedimentological and paleo-ecological assessment of carbonate platform successions. These tools will be applied both to platform and coeval basinal successions in order to characterize the differential response mechanisms of neritic versus basinal responses to Early Jurassic carbon cycle perturbations along the southwestern Tethyan margin.