Tectonic reactivation and ore-forming fault systems from the west African Craton margin (Saghro, Anti Atlas, Morocco)

This study provides interpreted aeromagnetic databases combined with structural and metallographic investigation to examine the surface versus subsurface faults interaction and the tectonic pattern of fault-driven mineralization in the Southwestern Saghro massif (Eastern Anti-Atlas, Morocco). Many Precambrian inherited faults have undergone considerable tectonic remobilization, exhibiting mainly normal/strike-slip (e.g., Ouad Dar'a caldera and Tagmout graben bounding faults) and reverse (e.g., Sidi Flah fault) kinematics observed, respectively, in the Precambrian-Cambrian and Precambrian-Quaternary contact zones. This tectonic process points to the multi-reactivation of the NE to ENE fault system during the Variscan and Alpine cycles. Analyzing the correlation between fault depth data and ore occurrences reveals that the most significant sulfide-bearing Cu–Pb–Ag–Zn (Au–Ag) veins are carried by NW to NNW and NE to ENE deep (∼900m) structurally reworked faults. Metallographic analysis of samples from these tectonic damage zones yields hypogenic (pyrite, chalcopyrite, galena, sphalerite) and secondary (malachite, azurite, and covellite) sulfide minerals. Such potential ore-bearing structures occur only (or mostly) within the Neoproterozoic basement (e.g., Bou Skour and Bou Isserfan vein-type deposits), implying a Pan-African tectonic-metallogenic control. Conversely, NNE to NE-trending barite structures are evident in both Precambrian and Cambrian outcrops. Their geometry attests to an oblique-slip opening movement consistent with the NW-SE Atlantic rifting, as discussed for the barite deposit of the nearby Ougnat massif. The findings of this study have the potential to significantly advance current knowledge of the spatio-temporal relationships between tectonics and mineralization in the Anti-Atlas belt along the northern edge of the West African Craton (WAC). •Surface-subsurface faults interaction is highlighted using aeromagnetic and structural data.•Precambrian faults, remobilized during Variscan and Alpine cycles, exhibit normal/strike-slip and reverse kinematics.•Correlation between fault depth and ore occurrences highlights sulfide-bearing veins along NW to NNW and NE to ENE reworked faults.•Deep (∼900m) polymetallic-bearing veins are confined to the Neoproterozoic basement, suggesting a Pan-African tectonic-metallogenic control.•Oblique-slip opening faults bearing barite veins are consistent with the NW-SE Atlantic rifting.