Associations et biostratigraphie des Foraminifères benthiques et planctoniques du Bédoulien sommital et du Gargasien inférieur de La Tuilière - St-Saturnin-lès-Apt

Abstract

Research on the Bedoulian and Gargasian of the Cassis-La Bedoule (Bouches du Rhone, SE France) area is extended, by a study of four overlapping sections in the stratotypic area of the Aptian stage in the hamlet of La Tuiliere (commune of Saint-Saturnin-les-Apt, Vaucluse, SE France). This new information permitted a detailed analysis of upper Bedoulian and lower Gargasian benthic (30 taxa) and planktonic (15 taxa) foraminiferal assemblages. Here we describe, illustrate and give the ranges and distribution of the most significant forms, and call attention to several benthic and planktonic species that may serve as extra-regional markers. The study of the planktonics in these expanded and continuous sections made it possible to strengthen the zonation which had been established in the Lower Aptian stratotype of Cassis-La Bedoule, i.e. a succession of five zones (cabri, luterbacheri, ferreolensis, barri, algerianus); this zonal scheme is improved by the addition of a horizon with Globigerinelloides ferreolensis heptacameratus nov. subsp., which straddles the boundary between the luterbacheri and ferreolensis zones. We also show the temporal quasi-coincidence of: 1) the top of the Furcata ammonite Zone, 2) the lithological named change of color and 3) a triple micropaleontological datum (FAD of Praehedbergella luterbacheri, LAD of Protocythere bedoulensis and Lenticulina cf. nodosa) of which the importance in the stratotype of Cassis-La Bedoule had already been pointed out. All these data may be valuable in the definition of the Bedoulian-Gargasian boundary. Within the luterbacheri Zone of the early Gargasian, an episode probably of volcanic origin that we interpret as the equivalent of the Van Gogh Level (initially detected in the Vocontian domain), is marked by a strong crisis in the diversity of epibenthic and planktonic foraminifers, as well as in that of the ostracodes. From a paleoecological and paleobiogeographical point of view, a comparison of the benthic and planktonic foraminiferal assemblages of La Tuiliere with those of neighbouring areas reveals specific features related to paleodepth and shows affinities which appear to be closer with the microfaunas of certain boreal areas (e.g. northern Germany) than with the Tethysian realm.