The Cretaceous–Paleogene Boundary in the Tebessa Region (NE-Algeria): First Biostratigraphic and Geochemical Record

A new study for the Cretaceous–Paleogene Boundary (KPB) is proposed at Djebel Dyr (Tebessa, NE Algeria), based on biostratigraphic and geochemical evidence. Detailed investigations on the El Haria Formation mainly composed of marly to argillaceous lithologies reveal five KPB marker criteria. These are (1) mass extinction of all Maastrichtian planktic foraminifera, except Guembelitria cretacea; (2) evolution of the first tertiary species; (3) a KPB iron hydroxide (goethite) layer; (4) iridium (Ir) content anomaly; and (5) a sharp decrease in CaCO3 contents, down to ∼0%. Thanks to the high-resolution sampling and the evolution of the index species across this interval, we propose a new biozonation considred valid for low-to-middle latitudes, which includes four biozones: Plummerita hantkeninoides Zone, indicating the Late Maastrichtian; Guembelitria cretacea Zone (D1); Parvularugoglobigerina eugubina Zone (D2); and Parasubbotina pseudobulloides Zone (D3). The latter is subdivided into two subzones: the Eoglobigerina trivialis (D3a) and Subbotina triloculinoides (D3b), which specify the Lower Danian. Therefore, nine new planktic foraminifera species have evolved during this period. According to all this evidence, the Dyr section is considered one of the most complete sections clearly showing affinities with the Cretaceous–Paleogene Boundary (KPB) in a pelagic domain of the Tethys.