Sedimentological and sequence stratigraphy analyses of the syn-rift Triassic series of the Mohammedia–Benslimane–ElGara–Berrechid basin (Moroccan Meseta)

Sedimentological analysis has shown that during the syn-rift phase (Upper Triassic) the Mohammedia–Benslimane–ElGara–Berrechid basin (MBEB) is characterized by detrital and evaporite sediment filling. A gradual decrease of palaeoslope over time led to the evolution of paleoenvironments of proximal alluvial fans system to braided rivers and then to an anastomosing system. These environments evolve finally to an alluvial plain associated with a coastal plain where playa lakes, mudflats and lagoons had developed.We have identified fourteen genetic sequences which are included in four progradational-retrogradational minor cycles that are themselves grouped in one major cycle. These cycles are related to the variations of the base level. The dominance of the retrogradation phases giving an asymmetrical appearance to the cycles is related to the predominance of the base level rise. These variations are probably of allocyclic origin: tectonic and probably climatic, in relation with the Tethys and the Atlantic Ocean being opened

Sedimentological and sequence stratigraphy analyses of the syn-rift Triassic series of the Mohammedia–Benslimane–ElGara–Berrechid basin (Moroccan Meseta)

Sedimentological analysis has shown that during the syn-rift phase (Upper Triassic) the Mohammedia–Benslimane–ElGara–Berrechid basin (MBEB) is characterized by detrital and evaporite sediment filling. A gradual decrease of palaeoslope over time led to the evolution of paleoenvironments of proximal alluvial fans system to braided rivers and then to an anastomosing system. These environments evolve finally to an alluvial plain associated with a coastal plain where playa lakes, mudflats and lagoons had developed.We have identified fourteen genetic sequences which are included in four progradational-retrogradational minor cycles that are themselves grouped in one major cycle. These cycles are related to the variations of the base level. The dominance of the retrogradation phases giving an asymmetrical appearance to the cycles is related to the predominance of the base level rise. These variations are probably of allocyclic origin: tectonic and probably climatic, in relation with the Tethys and the Atlantic Ocean being opened

Répartition stratigraphique et biozones des kystes de dinoflagellés au passage Jurassique moyen–Jurassique supérieur (Bathonien supérieur–Oxfordien inférieur) dans le Bassin de Guercif, Maroc nord-oriental

Despite the stratigraphical significance of dinoflagellate cysts as reliable markers for correlating and dating Jurassic–Cretaceous strata, investigations into this palynomorph group in the southern Tethyan Realm, specifically northwest Africa, are sparse and somewhat parochial. Most research on Jurassic dinoflagellate cysts is focussed on European depocentres in the Boreal and Sub-Boreal realms. This study is on biostratigraphical data from two petroleum boreholes (MSD1 and KDH1) drilled during 1985 in the Guercif Basin, northeast Morocco by ONAREP (Office National de Recherche et d’Exploitation Pétrolier), now ONHYM (Office National des Hydrocarbures et des Mines). These boreholes penetrated a thick siliciclastic succession, attributed to the Middle and Upper Jurassic, below Miocene marls. Over sixty dinoflagellate cyst taxa were identified. Four dinoflagellate cyst biozones, named GI to GIV, are established for the late Bathonian to early Oxfordian interval. These biozones are defined on the basis of the first appearance datum (FAD) and/or the last appearance datum (LAD) of some biomarker taxa which have wide geographical distributions. These are: Ctenidodinium combazii and Ctenidodinium sellwoodii for the GI Biozone (late Bathonian–early Callovian); Ctenidodinium continuum and Meiourogonyaulax caytonensis for the GII Biozone (middle Callovian); Gonyaulacysta centriconnata and Wanaea thysanota for the GIII Biozone (late Callovian–earliest Oxfordian); and Liesbergia liesbergensis and Systematophora penicillata for the GIV Biozone (early Oxfordian). These biozones are correlated to those already established for the respective intervals in other palaeogeographic regions, such as the Boreal, Sub-boreal and Tethyan realms

Serie Stephano-permienne de la region de Marrakech, Maroc (Haut-Atlas nord, sondages du Haouz, Jbilets orientales) : dynamique sedimentale, petrographie, charbon

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc