L'Estellon (Baronnies, France), a "Rosetta Stone" for the Urgonian biostratigraphy

Bruno Granier (1) , Bernard Clavel (2) , Michel Moullade (3) , Robert Busnardo (4) , Jean Charollais (5) , Guy Tronchetti (6) , Pierre Desjacques (5)

1 DEEB - Department of Ecology and Evolutionary Biology
2 personne privée
3 Centre de recherches micropaléontologiques
4 personne privée
5 UNIGE - Université de Genève = University of Geneva
6 Laboratoire de Géologie des Systèmes et des Réservoirs carbonatés

Shallow-water assemblages of transported ("freshly reworked") bioclasts (mainly orbitolinids and dasycladales) are observed in the deeper facies of the "Vocontian Trough" (SE France). There these benthic assemblages can be directly correlated with ammonite zones. These new finds give an Early Barremian age to the earliest record of Palorbitolina lenticularis as well as those of four so-called "typical Early Aptian" representatives of the genus Orbitolinopsis. Actually most orbitolinid species recorded from the Late Barremian interval are now found present in Lower Barremian strata at L'Estellon. Some currently used correlation schemes for the Urgonian platforms, that are based on partial stratigraphic distribution ranges for the orbitolinids, --and consequently derived conclusions and hypotheses-- require at least in-depth revisions when they are not definitively refuted.

Mots clés: orbitolinids; Dasycladales; ammonites; biostratigraphy; biostratigraphic calibration; Barremian; Urgonian

Domaines: Stratigraphie

Bruno Granier, Bernard Clavel, Michel Moullade, Robert Busnardo, Jean Charollais, et al.. L'Estellon (Baronnies, France), a "Rosetta Stone" for the Urgonian biostratigraphy. Carnets de Géologie / Notebooks on Geology, 2013, CG2013 (A04), pp.163-207. ⟨10.4267/2042/51213⟩. ⟨hal-00908238⟩