The Carboniferous formations of Migoumess, Tirhela and Idmarrach (central Morocco): lithology, biostratigraphy and geodynamic consequences

New biostratigraphical data based on foraminifers, algae and pseudoalgae indicate that the limestone pebbles of the channelized polygenic conglomerates of the Migoumess formation contain Late Visean (V3bgamma-V3c) assemblages. That confirms the Westphalian age attributed to this formation by Hollard [Zdt. Geol. Ges. 129 (1978) 495-512]. The Tournaisian age assigned to it by palynology [C. R. Acad. Sci. Paris, serie II 310 (1990) 1573-1576] cannot be retained. The Tirhela formation, Late Visean and Serpukhovian (E1) in age, is coeval with the Akerchi formation [Berkhli, these d'Etat, 1999; Berkhli et al., J. Afr. Earth Sci. (accepte)]. The Idmarrach formation, mapped as a thrust sheet [C. R. Acad. Sci. Paris, serie II 310 (1990) 1573-1576], is dated as Serpukhovian (El) and its thrusting is consequently post-Serpukhovian. Palaeogeographic and geodynamic consequences are listed.