Stratigraphic and structural revision of the Upper Mesozoic succession of the Dadès valley, eastern Ouarzazate Basin (Morocco)

The paper presents a stratigraphic and structural revision of the Late Mesozoic succession exposed in the Dadès River valley (eastern Ouarzazate Basin), at the southern front of the Central High Atlas. Facies analysis, recognition of different rank erosional, angular and progressive unconformities and new paleontological data, allowed a subdivision into five units of four formations formerly ascribed to the Late Cretaceous. The local stratigraphy is tentatively correlated with the Middle Jurassic-Upper Cretaceous successions exposed in different sectors of the Central High Atlas. Integrated structural and stratigraphic data led to infer a predominant tectonically-driven development of these units. The local tectono-depositional scenario suggests since the Middle-Late Jurassic the occurrence of southward-directed fluvial systems sourced from an uplifting basement high in the axial portion of the Central High Atlas and paired to an incipient foreland basin confined by the Anti-Atlasic ranges. Crustal shortening may have caused an early tectonic inversion of the basement high progressively propagated to the south with subsequent deformation of the sedimentary cover.