An account of the lower Aptian ammonites of the Niveau Goguel (= OAE 1a) in the Vocontian Basin, SE France

Abstract

It has long been claimed that ammonites are scarce, if not completely absent, during the deposition of the Oceanic Anoxic Event 1a, locally known as the Niveau Goguel (NG), in the Vocontian Basin, SE France. Here we provide the first description of ammonites found within, and above, the NG from three Vocontian key sections (Saint-Jaume, Serre Chaitieu, and Les Sauzeries-Basses). The ammonite fauna studied represents almost a hundred of specimens, most of which have been collected in situ and calibrated with the high-resolution lithostratigraphical framework previously established in those sections. The following palaeontological identifications are by no means to be considered as definitive and many taxa are left in open nomenclature pending more materiel to be collected. The collected material gives evidence of the upper Deshayesites forbesi Zone during the deposition of the NG, as well as the upper Deshayesites deshayesi Zone and upper Dufrenoyia furcata Zone in the overlying strata, that around the Niveau Blanc sensu lato (NB s.s.).