New sections of the Cretaceous–Paleogene transition in the southwestern Tethys (Médéa, northern Algeria): planktic foraminiferal biostratigraphy and biochronology

Abstract

Two sections (Sidi Ziane and Djebel Zakhamoune from Medea, northern Algeria) of the Cretaceous–Paleogene (K–Pg) transition have been found, sampled, and studied in detail for the first time in Algeria. In order to obtain a biochronological control to evaluate the potential of the Medea area for the study of the K/Pg boundary event and close paleoclimatic episodes as LMWE and Dan-C2, we have reviewed the biostratigraphical scales with planktic foraminifera from the uppermost Maastrichtian to the middle Danian and dated the main key bioevents through graphic correlations comparing the Bottaccione (Italy), Agost and Caravaca (Spain), and Kalaat Senan (Tunisia) sections. The biostratigraphic study has revealed the presence of the last biozone of the Maastrichtian in both sections (zone CF1 or Plummerita hantkeninoides zone). The thickness of this biozone (13.5 m in Sidi Ziane and 9 m in Djebel Zakhamoune) is one of the largest identified to date, suggesting that the uppermost Maastrichtian is complete and continuous in the Medea area. Based on graphic correlation, it has been determined that sedimentation rates of the Maastrichtian in Sidi Ziane and Djebel Zakhamoune are, respectively, 8.98 and 6.58 cm/kyr, only comparable with the most expanded and continuous sections worldwide, such as Ain Settara (Kalaat Senan). It has also recognized a hiatus affecting the lower Danian in both sections, estimated in 610.4 and 644.9 kyr long in Djebel Zakhamoune and Sidi Ziane, respectively. Nevertheless, the presence of reworked specimens of the index species Parvularugoglobigerina longiapertura strongly suggests that the lowermost Danian may be recorded in the Medea area.