Les foraminifères de l'Éocène du Bassin de l'Adour (Aquitaine, France): Biostratigraphie et taxinomie

Abstract

The small foraminiferal fauna of the Adour Basin Eocene formations was reviewed from about 1,300 samples. The planktonic foraminifers were used both for placing these formations in the Toumarkine & Luterbacher's biozones (1985) and correlating them with the Berggren et al. (1995) and Canudo & Molina's (1992) parallel patterns. A finer subdivision into sixteen Aquitaine-specific units (EPA 1–16) is also put forward. A benthic foraminifer-based biozonation, such as the Berggren & Miller's one (1989) for bathyal foraminifers and the Serra-Kiel et al. (1998) biozonation of larger foraminifers can be implemented in Aquitaine after being slightly adjusted. The new ideas about the Bartonian-Priabonan boundary (Serra-Kiel et al., 1998), which is assumed to occur in the Globigerinatheka semiinvoluta zone, are discussed as well. The formation dating at the stage level is possible through the smaller benthic foraminifers, using both appearances and disappearances. The varying diversity of the foraminifers reflects that of the paleoenvironments: the disappearance of bathyal facies brings about the migration of species and the temporary disappearance thereof from the basin. It seems the paleoclimate hardly affected the diversity. The South Aquitaine Eocene fauna comprises 887 foraminifer species and 9 forms that are classified under Bryozoans (formerly incertae sedis). Ten new species and one new genus are proposed: Spiroplectammina liebusi n. sp., Globocassidulina ornata n. sp., G. hispida n. sp., Siphouvigerina primitiva n. sp., Reussella gohrbandti n. sp., Lobatula ? quadrilobata n. sp., Eoeponidella ? lobata n. sp., Charltonina ? ganensis n. sp., Thalmannita aquitanica n. sp. et Tarbellina plicata n. gen., n. sp.