Enregistrement des événements remarquables de la limite Crétacé–Tertiaire dans la coupe d'Ellès (Tunisie)

Abstract

Abstract The review of the Cretaceous–Paleogene interval deposits of the Elles section based on a detailed sampling gives a good characterization of the K/T boundary and reconstitution of the geological events underlining this boundary. Thus, the discovery of a thin Ir-rich layer, with Ni and Cr-rich spinel and shocked quartz is a well preserved record of the known cosmic event that occurred at that time. This sudden event is also corroborated by the quantitative and qualitative organic components distribution along the K/T interval. Added to some other long-term events (e.g. climatic, eustatic), it generated a mass extinction, at the K/T boundary, of specialists among the Globotruncanids and Heterohelicids planktic foraminifera species. Following this biological crisis, the biotic turnover into the Danian is slow. The underlining of all the Cretaceous–Tertiary interval biozones attests that the Elles section is complete. If compared to the K/T stratotype and El Kef II sections, the Elles section is found to display a better exposure of the K/T interval and shows more expanded zones and subzones. Such characteristics promote the Elles section to be considered as a parastratotype.