A Cretaceous–Palaeogene boundary geological site, revealed by planktic foraminifera and dinoflagellate cysts, at Ouled Haddou, eastern external Rif Chain, Morocco

•We study a Cretaceous–Palaeogene boundary geosite at Ouled Haddou.•High Planktic foraminifera and dinoflagellate cyst biostratigraphic resolution.•Complete and continuous Cretaceous–Palaeogene boundary transition.•Deposition in neritic (Maastricchtian) to open marine (Danian) conditions. Planktic foraminifera and organic-walled dinoflagellate cyst investigations in the Ouled Haddou outcrop (eastern external Rif Belt) in northern Morocco, revealed a continuous sedimentation and a complete record of the Cretaceous–Palaeogene (K–Pg) transition. Both planktic foraminifera and dinoflagellate cyst assemblages observed in the studied Maastrichtian–Danian boundary interval are diverse and well-preserved and contain numerous chronostratigraphically significant bio-events that have allowed a high resolution biostratigraphic analysis, based on the first and last occurrences of index species and also on the massive disappearance and abundance changes of different taxa. Planktic foraminifera allow correlation of the studied interval with the uppermost Maastrichtian Abathomphalus mayaroensis Zone and the lower Danian Guembelitria cretacea, Parvularugoglobigerina eugubina, Parasubbotina pseudobulloides and Subbotina triloculinoides zones. A mass extinction of planktic foraminifera is observed at the end of the Abathomphalus mayaroensis Zone. This mass extinction is followed by three renewal steps of planktic foraminifera in the basal Danian. The Cretaceous–Palaeogene boundary is placed just above the mass extinction of Globotruncanids and Heterohelicids and below the first appearences of earliest Danian markers genera Globoconusa, and Parvularugoglobigerina. According to dinoflagellate cysts, the recognition of the latest Maastrichtian and earliest Danian is based on global bio-events, including the first occurrence of the latest Maastrichtian species Disphaerogena carposphaeropsis, Glaphyrocysta perforata, and Manumiella seelandica, the latest Maastrichtian acme of Manumiella seelandica, and the first occurrence of the earliest Danian markers Carpatella cornuta, Damassadinium californicum and Senoniasphaera inornata. The dinoflagellate Damassadinium californicum Zone characterizing the Danian in the Northern Hemisphere is recognized in this section. The Cretaceous–Palaeogene boundary is placed, at the same position determined by Planktic foraminifera, immediately above the acme of Manumiella seelandica and the last appearance of few Cretaceous taxa such as Dinogymnium