More gaps than record! A new look at the Pliensbachian/Toarcian boundary event guided by coupled chemo-sequence stratigraphy

The Pliensbachian/Toarcian boundary (Pl/To) event precedes by ca. 1 Myr the onset of Toarcian Oceanic Anoxic Event. It corresponds to a second order mass extinction associated with an outstanding collapse shallow marine ecosystems at global scale. Yet, our knowledge about its exact driver(s) and unfolding is relatively ambiguous due numerous hiatuses present in sedimentary record during this critical time interval. In study, integrated carbon isotope chemostratigraphy sequence stratigraphy approach applied two case studies (the upper Pliensbachian South-East France Pliensbachian–Toarcian transition Morocco) demonstrate how major changes sea-level sedimentation supply accompanying Pl/To led formation ubiquitous, often cryptic hiatal surfaces record. Hence, as consequence strongly progradational stacking pattern latest related lowstand cold greenhouse climate, proximal settings were characterized bypass and/or erosion, inducing incomplete Spinatum chronozone localities situated outer part basins. earliest Toarcian, neritic carbonate factory halt mud export into basin, resulting sediment starvation most basins carbonate-dominated regime before environmental perturbation. Only where vigorous siliciclastic took over are likely have more complete immediate aftermath production collapse. This combination causes explains ubiquitous incompleteness European bulk current understanding derives from. A comparison between known expanded records Llanbedr (Mochras Farm) core Wales Bou Oumardoul n'Imazighn section Morocco shows that perturbations positive excursion spanning boundary. followed negative coincides ample fall.