Odette Ducasse

Étude de populations du genre Protoargilloecia (ostracodes) dans les faciès bathyaux du Paléogène aquitain: Deuxième test effectué en domaine profond. Comparaison avec le genre Cytherella

One of the common genera in epi- mesobathyalenvironments during the Aquitaine Paleogene is Protoargilloecia. This is represented only by one species: P. angulata Deltel, the diversity of which results into two morphs: «acuminate and «plump types. They are described and illustrated. Following a populational study in the Antares 101drilling site, it has been established that the evolution of this species is stabilizing. Faunal observations have also indicated that during Upper Eocene and Lower Oligocene the environment underwent changes engendered by large continental input fluxes. The geographical distribution of the Protoargilloeciais defined in the Aquitaine Basin. The Cytherella and Protoargilloecia genera-analysedaccording to the same methods and envisaged within the same environmental conditions- are subsequently compared. There are observed a similar type of evolution as well as similar reactions to episodic environment transformations.

Ostracofaune et caractérisationdes paléoenvironnements á la limite Oligocène-Miocène en Aquitaine

Ostracod faunal associations have been identified in many outcrops distributed all over the Aquitaine basin. They are referred to middle Oligocene (Stampian), upper Oligocene (Chattian), lower Miocene (Aquitanian and Burdigalian). These ostracod assemblages make it possible to distinguish the following different palaeoenvironments: continental environment, brackish ones, coastal and phytal sublittoral ones and circalittoral to epibathyal one. Each type of environment, according to its age, is characterized by a reference level and the main represented species.