Characteristic events record of the K/T boundary in the Elles section (Tunisia).

The review of the Cretaceous-Paleogene interval deposits of the Elles secti on based on a detailed sampling gives a good characterization of the WT bou ndary and reconstitution of the geological events underlining this boundary . Thus, the discovery of a thin Ir-rich layer, with Ni and Cr-rich spinel a nd 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 quant itative and qualitative organic components distribution along the WT interv al. Added to some other long-term events (e.g. climatic, eustatic), it gene rated a mass extinction, at the WT boundary, of specialists among the Globo truncanids and Heterohelicids planktic foraminifera species. Following this biological crisis, the biotic turnover into the Danian is slow. The underl ining of all the Cretaceous-Tertiary interval biozones attests that the Ell is section is complete. If compared to the WT stratotype and Fl Kef II sect ions. the Elles section is found to display a better exposure of the WT int erval and shows more expanded zones and subzones. Such characteristics prom ote the Elles section to be considered as a parastratotype. (C) 2000 Academ ie des sciences/Editions scientifiques et medicales Elsevier SAS.