A palynological investigation of a section dated by foraminifera, at Ouled Haddou, south-eastern Rifian Corridor, northern Morocco, revealed a rich and well-preserved dinoflagellate cyst assemblage that allowed a palynological separation of Maastrichtian from Danian deposits. The gradual change of the dinoflagellate cyst assemblages and the biostratigraphic resolution attained, suggest that the studied Maastrichtian-Danian section is continuous. The recognition of the latest Maastrichtian and earliest Danian is based on global dinoflagellate cyst 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, Eisenackia circumtabulata, Membranilarnacia tenella and Senoniasphaera inornata. The Cretaceous-Paleogene boundary is placed above the latest Maastrichtian events, mainly immediately above the acme of M. seelandica and below the earliest Danian events, particularly below the first occurrences of C. cornuta and D. californicum. The biostratigraphic interpretations are based on a comparison with calibrated dinoflagellate cyst ranges from several reference sections, mainly in the Northern Hemisphere middle latitudes. The Cretaceous-Paleogene boundary is not marked by a mass extinction of dinoflagellate cyst species, but shows important changes in the relative abundances of different species or groups of morphologically related species. These changes are paleoenvironmentally controlled. The peridinioid assemblage suggests deposition in a subtropical to warm temperate province. One dinoflagellate cyst species, Phelodinium elongatum, is formally described.

A palynological study of the Chalk Group (Campanian-Danian) in the Meer borehole (northern Belgium), which penetrated the thickest succession known in the Campine Basin, has revealed diverse, well-preserved organic-walled dinoflagellate cyst assemblages. The succession contains numerous chronostratigraphically significant dinocyst events, which are based mainly on the highest consistent occurrences of index species. At least 35 bio-events have enabled a subdivision into nine intervals, at stage or substage level, within the Campanian to Danian interval, as based on comparison with coeval assemblages elsewhere in northwest Europe, inclusive of stratotypes of stages and stage boundaries. Bio-events allow correlation of the section studied with the Campanian Exochosphaeridium? masureae, Areoligera coronata and Samlandia mayi zones, the Maastrichtian Pervosphaeridium tubuloaculeatum, Deflandrea galeata and Hystrichostrogylon coninckii zones, and the Danian Damassadinium californicum Zone. In addition, a correlation with other zonal schemes for the southern North Sea Basin and with conventional northwest European belemnite zones is presented. Comparisons with Boreal and Tethyan realms confirm that most bio-events may also be useful for interregional and global correlation. The Campanian-Danian dinocyst biostratigraphy of the Meer borehole is put alongside geophysical well logs and an ecozonation, in order to check the validity of lithostratigraphical correlations across the Campine Basin. This first, detailed correlation attempt shows that sensitivities to facies change associated with differences in accommodation space and sediment supply appear to be at the base of slight, yet consistent, shifts between the local lithological succession and the standard lithostratigraphical scheme of the Maastricht type area.

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