Late Barremian–early Aptian ammonite bioevents from the Urgonian-type series of Provence, southeast France: Regional stratigraphic correlations and implications for dating the peri-Vocontian carbonate platforms

Camille Frau (1) , Anthony J.-B. Tendil (2) , Cyprien Lanteaume (2) , Jean-Pierre Masse (3) , Antoine Pictet (4) , Luc Bulot (2) , Tim Luber , Jonathan Redfern , Jean Borgomano (5) , Philippe Leonide (6) , François Fournier (3) , Gérard Massonnat (7)

1 Groupement d'Intérêt Paléontologique
2 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
3 AMU - Aix Marseille Université
4 Institute of Earth Sciences
5 CSTJF - Centre scientifique et Technique Jean Feger
6 FRE 2761 - Géologie des Systèmes Carbonatés
7 MIGP - Laboratoire de Modélisation et d'Imagerie en Géosciences de Pau

This work provides a new ammonite age-calibration of the rudistid limestones of the Urgonian-type Provence carbonate platform (Southeast France) based on sampling along three ~200 km-long platform-to-basin transects and re-examination of historical collections. Ammonite key findings indicate that the first rudistid platform stage (including the Agriopleura and requieniidemonopleurid beds) develops and spreads northward through the Toxancyloceras vandenheckii-Gerhardtia sartousiana zones interval (lower upper Barremian). This stage is interrupted by the tectonically-induced deepening of the southern Provence domain during the Imerites giraudi Zone while the northern regions records the massive deposition of Palorbitolina-Heteraster beds. Recovery of the rudistid carbonate system is illustrated by the development of caprinid-bearing rudistid limestones in the North Provence domain through the Martelites sarasini Subzone (lower Martelites sarasini Zone, uppermost Barremian), which shows a bidirectional progradation toward the South Provence and Vocontian basins. The caprinid-bearing limestones terminate at a shortterm exposure and are overlain by cherty-oobioclastic deposits spanning the Pseudocrioceras waagenoides Subzone (upper M. sarasini Zone) to the lower Deshayesites forbesi Zone. A regional-wide flooding of the study area is illustrated by the abrupt change to a marl-dominated regime occurring in the upper D. forbesi Zone. Compared to the previous datings, the Barremian/Aptian boundary should be relocated in the lower part of the post-caprinid, cherty-oobioclastic deposits although its precise level cannot be fixed due to the lack of a continuous ammonite record. Ammonite age-calibration of the surrounding Urgonian rudistid platform series is discussed and gives evidence of a comparable twofold demise of the peri-Vocontian rudistid biota during the uppermost Barremian. Accordingly, the link between the final demise of the peri-Vocontian rudistid biota and the onset and/or culmination of the mid-early Aptian Oceanic Anoxic Event (OAE) 1a should be reconsidered.

Domaines: Stratigraphie; Paléontologie; Géochimie; Géologie appliquée

Camille Frau, Anthony J.-B. Tendil, Cyprien Lanteaume, Jean-Pierre Masse, Antoine Pictet, et al.. Late Barremian–early Aptian ammonite bioevents from the Urgonian-type series of Provence, southeast France: Regional stratigraphic correlations and implications for dating the peri-Vocontian carbonate platforms. Cretaceous Research, 2018, 90, pp.222-253. ⟨10.1016/j.cretres.2018.04.008⟩. ⟨hal-02105471⟩