Abstract The Anti-Atlas belt belongs to the northern fringe of the West African craton, moderately deformed during the Variscan orogeny south of the Meseta Block. Field-based investigations into the stratigraphy and structure of the Palaeozoic cover have been performed in the eastern part of Anti-Atlas, with emphasis on the Devonian terranes. The Pan-African basement, which crops out in the Ougnat massif, was fragmented into a mosaic of tilted blocks during a sequence of extensional faulting events that occurred from Cambrian to (mostly) Late Devonian times. The Devonian normal fault pattern indicates a multi-directional extension, with a dominant northward direction. The Variscan compression resulted in the inversion of the palaeofaults as strike-slip–reverse faults, the kinematics of which points to a NE-trending regional direction of shortening, probably Permian in age. The occurrence of the Late Devonian palaeofault array accounts for the thick-skinned style of the (eastern) Anti-Atlas belt. The Devonian paleogeography of the Anti-Atlas can be correlated with that of the Meseta, but the lack of any Late Devonian compressional event in the Anti-Atlas shows that the two domains were not mechanically coupled at that time.

Abstract Broadly synchronous circum-Atlantic Variscan–Alleghanian orogenic belts developed during the Late Palaeozoic Gondwana–Laurentia collision. In the northern part of the West African craton (WAC), the Variscan orogeny produced basement-controlled structures in the Anti-Atlas, which represents the pericratonic foreland, now located south of the Variscan domains of Morocco and north of the Mauritanides belt. New structural field observations document the strong involvement of the basement and the inversion and folding of the Palaeozoic sedimentary basins at the edge the WAC. Two contrasting domains differently responding to regional NW–SE shortening are recognized: (1) a narrow belt along the Atlantic coast characterized by thin-skinned folding and ESE-vergent thrusting (para-autochthonous Anti-Atlas); (2) a large area between the WAC sensu stricto and the South Atlas front showing huge basement uplifts amidst a folded Palaeozoic cover with upright polyharmonic folds (autochthonous Anti-Atlas). The structural trend of the basement inliers is inherited at least in some case from previous Proterozoic fractures. Compressional reactivations led to basement uplift and concomitant folding of the Palaeozoic cover. Cover series are horizontally shortened by mostly upright symmetrical buckle folds of various wavelengths in response to thickness variations between abundant incompetent silt and shale horizons and rare competent carbonate and quartzite beds. Deformation is greatest near the borders of and between closely spaced basement uplifts. Regionally, deformation intensity decreases, either abruptly or progressively, towards the SE and it vanishes within the undeformed Tindouf basin.