Biostratigraphy, carbon isotope and sequence stratigraphy of South Tethyan Valanginian successions in the Essaouira-Agadir Basin (Morocco)

A detailed stratigraphic analysis was carried out on Valanginian deposits of six Moroccan sections of the Essaouira-Agadir Basin (EAB, South Tethyan margin) in order to characterize the Weissert Event and propose correlations with the North Tethyan margin (south-east France Basin). The studied successions consist of alternating marlstone and limestone beds with sandy intercalations, and are well exposed and relatively rich in ammonites. Ammonite biostratigraphy and sequence stratigraphy were established for all successions, whereas calcareous nannofossil and carbon stable isotope analyses were performed for two and five sections, respectively. For each succession, an accurate ammonite zonal scheme allows to recognize the standard zonation established for the Mediterranean Province. A calcareous nannofossil zonation is provided for Zalidou and Ait Hamouch, considered as reference sections. The detailed bio-zonations allowed to ascribe an accurate age for most of the sedimentary discontinuities and deposi-tional sequences identified in the EAB. East-west and north-south transects are established for the Valanginian depositional system. Despite some stratigraphic gaps, the Valanginian carbon isotope excursion (CIE) was recognized in most of the studied sections. The Moroccan successions are correlated with those of reference sections of south-east France i.e., the Vocontian Basin (Vergol-La Charce) and Provence Platform (Carajuan), using bio-sequence-chemo-stratigraphy. These inter-basin correlations allowed to evidence major mid-Valanginian and upper Valanginian eustatic regressions; the possible role of tectonics and glacio-eustacy is also discussed. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

A detailed stratigraphic analysis was conducted on Valanginian deposits of the Essaouira-Agadir Basin in Morocco to characterize the Weissert Event and establish correlations with the North Tethyan margin. The study utilized ammonite biostratigraphy, sequence stratigraphy, calcareous nannofossil analysis, and carbon stable isotope analysis to establish inter-basin correlations and reveal the age of sedimentary discontinuities and depositional sequences.