The ‘Rich’ group of the Drâa Basin (Lower Devonian, Anti-Atlas, Morocco): an integrated sedimentary and tectonic approach

Abstract

AbstractIn this study, based on a sedimentary analysis, an interpretation in terms of sequence stratigraphy is proposed for the ‘Rich’ group of the Early Devonian Drâa Basin (of Pragian to late Eifelian age). This group is composed of four depositional sequences (third order) containing a transgressive systems tract and a highstand systems tract, both deposited on a storm- and tide-dominated shelf. The depositional sequences are related to global sea-level changes but their geometric architecture is controlled by tectonic subsidence and by sediment supply. The basin forms an ENE–WSW channel with two internal high blocks acting on the depocentre shifts. The channel is surrounded by high points and by marine distal condensed series, and bordered by inherited various regional faulted axes. The regional setting corresponds to an extensional passive margin on the northern edge of the West African craton.