effectuée dans deux bassins différents durant l'Arénig-Llanvirn. Dans le bassin du Haut Atlas occidental s'est développé un delta influencé par vagues et tempêtes, alimenté par une source située à l'emplacement actuel du couloir d'Argana et soumis à des fluctuations eustatiques et à la subsidence. Dans le Haut Atlas central se sont développés des deltas influencés par la marée et les tempêtes épisodiques et des estuaires qui étaient alimentés par des sources situées à l'emplacement actuel des massifs du Siroua et de l'Ouzellagh et soumis à des fluctuations eustatiques et une tectonique verticale.

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Detailed sequence stratigraphy of the Eocene-Miocene Mrayt Group in North-Western Rif (Morocco), allow identifying the nature and the sources of the sediment supplies, the sedimentary facies and the depositional environments as well as the factors that controlled the sedimentation. This work made it also possible to identify 16 facies sequences that have never been described before. facies sequences, indicate that the sedimentation occurs under a complex hydrodynamics strongly influenced by river discharge, tidal currents and wave’s processes in an estuary, a tide dominated delta and waves and tide dominated nearshore. These depositional systems occur at the margin of the Maghrebian foredeep sedimentary basin under the interplay of climate, tectonic and eustacy.

The sedimentary deposits of Eocene-Miocene Mrayt Group, North-Western Rif, Morocco has been the subject of controversy by previous authors regarding their depositional environment. Detailed sedimentological study based on petrographic and sedimentary facies analysis, ichnofacies interpretation and paleocurrent measurements, leads to several results and new insights. Petrographic study provided the first evidence of mixed siliciclastic and carbonate sediments and their nomenclature: silty micrites, micritic siltstones, micritic sandstones, sandy micrite, and allochemic sandstones, as well as the nature of the sources and its geological context. Twenty two sedimentary facies that have never been described before are identified, and based on their succession and association a new interpretation of depositional processes and depositional systems are proposed. The paleoenvironments of the Mrayt Group are interpreted as littoral and shallow marine settings: tides- dominated estuary, tides-dominated delta systems and open coast tidal flat, under complex hydrodynamics strongly influenced by river discharge, tidal currents, waves and storms action.Sedimentation occurred in “the Maghrebian basin” under the interplay of: i) tectonics related to the Cenozoic collision of the African and Eurasian continental plates, ii) Cenozoic alternation of warm climate and cooling due to the increasing influence of Antarctica glaciation, iii) sediments supplies induced by rejuvenation of sedimentary sources and iv) sea level fluctuation related to the advance and retreat of ice-sheet on Antarctica.

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