The Eocene-Oligocene (E-O) transition was an epoch of great turnover, in both terrestrial and marine environments. Mammals were highly affected by an extinction event called grande coupure of Stehlin, which has been very well documented in Europe and Asia (Hartenberger, 1998). In America the tropical molluscs underwent a significant extinction event at the beginning of the Oi-1 glaciation in the Oligocene (Hickman, 2003). This drop in temperature was caused by the opening of the Drake Strait, thereby giving rise to the circum Antarctic current, the formation of ice caps on the poles and the development of the psychrosphere in

Biostratigraphic analysis of the Eocene-Oligocene transition (E-O) at the Menzel Bou Zelfa and Jhaff composite section in the Cap Bon Peninsula (North East Tunisia) allowed us to recognize a continuous planktic foraminiferal biozonation: E14 Globigerinatheka semiinvoluta Zone, E15 Globigerinatheka index Zone, E16 Hantkenina alabamensis Zone and O1 Pseudohastigerina naguewichiensis Zone. A quantitative study of benthic and planktic foraminifera assemblages was carried out and the richness and diversity of foraminifera allowed us to reconstruct the paleoenvironmental evolution from marine to terrestrial environments. From the Eocene E14 Zone, the foraminiferal association characterizes a relatively warm climate with considerable oxygen content and a dominance of keeled and spinose planktic foraminifera, which became extinct at the E/O boundary, possibly due to cooling of the planktic environment. Nevertheless, the small benthic foraminifera do not show an extinction event at the Eocene/Oligocene (E/O) boundary, indicating that the benthic environment was not significantly affected. In the basal Oligocene O1 Zone, the benthic environment changes to a shallower setting due to cooling of the climate. These changes generated a remarkable dominance of globular forms in the planktic environment. Small benthic foraminifera apparently have a gradual extinction event, or more likely a gradual pattern of local disappearances, that could have been caused by the Oi1 glaciation.

No abstract

The foraminiferal analysis at the Danian/Selandian boundary of the Nukhul section (Egypt) enabled us to determine the biozones of Praemurica uncinata (P2); Morozovella angulata (P3a); Igorina albeari (P3b), and Acarinina soldadoensis/Globanomalina pseudomenardii (P4c). Thus, the base of Selandian is defined by the first occurrence of I. albeari and the P4c subzone covers unconformably the P3b subzone. The quantitative and qualitative analysis of the planktonic and benthic foraminifera assemblages and the isotopic analysis permitted characterization of the paleoclimate and paleoenvironment. Thus, at the middle to upper Danian, the environment was marine intertidal under a relatively cold climate. At the lower Selandian base of the Thanetian, a rise in the sea level was recorded and the warmer climatic conditions seem to be settling. In the upper Thanetian, we note the installation of colder weather conditions and a further sudden drop in sea level.