Elsevier

Cretaceous Research

Volume 140, December 2022, 105341
Cretaceous Research

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

https://doi.org/10.1016/j.cretres.2022.105341Get rights and content

Highlights

  • Integrated stratigraphy is proposed for South Tethyan Valanginian sections in Morocco.

  • Detailed ammonite ranges and depositional sequences are described for all sections.

  • Calcareous nannofossil and ammonite zonations are calibrated for two sections.

  • The mid–Valanginian Weissert Event is characterized through carbon isotope analyses.

  • Moroccan sections are correlated with reference sections of south–east France.

Abstract

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 Aït Hamouch, considered as reference sections. The detailed biozonations allowed to ascribe an accurate age for most of the sedimentary discontinuities and depositional 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.

Keywords

Ammonite
Calcareous nannofossil
Depositional sequence
Weissert Event
Morocco
Inter-basin correlation

Data availability

Isotopic and calcareous nannofossil data are available in Supplementary Material.

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