The Berriasian–Valanginian boundary in the Mediterranean Province of the Tethyan Realm: Ammonite and calcareous nannofossil biostratigraphy of the Vergol section (Montbrun-les-Bains, SE France), candidate for the Valanginian GSSP

The Vergol locality (Montbrun-les-Bains, South-East France), a candidate section for the Valanginian GSSP (Global Stratotype Section and Point), was studied in detail ammonites calcareous nannofossils. A bed-by-bed sampling quantitative approach were carried out on this expanded succession presenting continuous record of calcareous-marl alternations covering uppermost Berriasian lowermost Valanginian. ammonite distribution observed allows precise characterization Berriasian–Valanginian boundary with recognition Tirnovella alpillensis (latest zone Berriasian) “Thurmanniceras” pertransiens (earliest Valanginian) standard zones. base is here defined by First Appearance Datum “T.” pertransiens; can be well-characterized assemblages using various nannofossil bioevents, like Occurrence Calcicalathina oblongata. tidy comparison previous works made order to integrate data calpionellids. discussion choice primary marker (ammonites versus calpionellids) proposed.