André Charrière

Nouvelles datations (Hauterivien supérieur–Barrémien inférieur) dans les « Couches rouges » continentales du Haut Atlas central marocain ; conséquences sur l’âge du magmatisme et des structurations mésozoïques de la chaîne Atlasique

Abstract In the Moroccan Central High Atlas, between the Bathonian and the Aptian, marine deposits are present in three continental formations. Known to be unfossiliferous for the main part, they are attributed to the Middle Jurassic or to the Lower Cretaceous, depending on the authors. Charophytes from the top of the second formation (Iouaridene Fm), and from the base of the third one (Jbel Sidal Formation), give an Upper Hauterivian–Lower Barremian age. Thanks to these biostratigraphical data, it has been possible to distinguish the different phases of the magmatic activity and the synsedimentary tectonic events, either linked to the closure of Tethyan Atlasic troughs during the Bathonian or associated with the development of the new basins, diachronous in the Atlasic Belt, during the Lower Cretaceous.

Microfaunes, microflores etpaléoenvironnements successifs dans la formation d'El Mers (Bathonien-?Callovien) du synclinal de Skoura (Moyen-Atlas, Maroc)

In the Middle-Atlas (Morocco), the lower part of the “Red beds” (El Mers Formation), Middle Jurassic in age,contains various microfossils which permit to reconstruct the palaeoenvironmental evolution of this area for this period. Populations of abundant charophytes, collected at the base of the formation, are assigned to a new species: Porochara hians Feist & Grambast-Fessard. Species of ostracods are generally different than the European synchronous ones. The first ostracods appearing at the base of the formation are monospecific and euryhaline (continental or brackish). They are more diversified above and correspond to a typical marine depositional environment. Marine incursions occur up to the top of the formation where they are represented by limestones bearing dasycladales and benthonic foraminifera, Late Bathonian to Early Callovian in age. The transgressive trend observed at the top of the “El Mers Formation” can be correlated to the deepening-upward trend of the Transgressive Systems Tract from the Depositional Sequence DS 158,5 (3rd order eustatic cycle LZA 3-1) which corresponds to a general transgression of the sea over the palaeostructures of the Jurassic Tethyan Basin.

Âges et environnements des Couches rouges d'Anoual (Jurassique moyen et Crétacé inférieur, Haut-Atlas oriental, Maroc)

Lithology, sedimentology and palaeoenvironments allow a lithostratigraphic subdivision of the Red beds into five formations. A marine episode identified near the top of the first formation is Early Bathonian in age. An erosional unconformity overlies this marine level just below the Lower Cretaceous deposits. It could be related to a large sedimentary gap between the Lower Bathonian and the Lower Cretaceous series.

Ostracodes non marins du Crétacé supérieur des Hauts Plateaux méridionaux, Maroc oriental

Upper Cretaceous non-marine ostracods from the southern High Plateaus, eastern Morocco.The marls of the upper part of the Tigri Formation in the Upper Cretaceous of the southern High Plateaus, eastern Morocco, reveal non-marine ostracod faunas from freshwater to oligohaline environments. Despite the poor specimen preservation, 23 species belonging to 14 genera have been recognized. The generic assemblages show a global paleobiogeographic distribution both on Laurasia