Sedimentology and Palaeoenvironments of the Triassic Deposits of the Imini Basin (High Atlas of Marrakesh, Morocco)

In this analytical work, we presented the facies and palaeoenvironments of the Triassic basin of Imini, in the southern sub-Atlasic area of the High Atlas of Marrakesh (80 km north of Ouarzazate). This basin was formed during the rifting phase that reactivated preexisting structures of the basement. The formations date to the Middle to Late Triassic. These are generally detrital and evaporitic sediments, capped by basaltic flows dating to the Late Triassic-Early Lias. The outcropping deposits are in discordance to Cambro-Ordovician schists of the basement. Our detailed sedimentological analysis identified facies associations with seven architectural elements (EA1 to EA7): CH (channels), GB (gravel bars and bedforms), SB (sandy bedforms), SG (sediment gravity flows), LS (laminated sand sheet), FF (overbank fines), and evaporites (Ev). Palaeoenvironments evolve from a proximal environment characterized by alluvial cones, to a braided fluvial environment, then to a distal fluvial environment with alluvial plains and playa lakes.