Regional geology and structural control of copper-bearing vein formation in the Western Anti-Atlas of Morocco

The Ouansimi copper mine is located south of the Kerdous inlier in the Western Anti-Atlas in Morocco. Neoproterozoic and Lower Cambrian sedimentary rocks record recurring transgressive and regression cycles by deposition of limestones, algae matts, or clastic rocks like conglomerates. The rocks are overprinted, likely due to the Variscan orogeny, resulting in an anticline formation showing internal large- and small-scale tectonic elements like folds, shearing, normal and reverse faults, as well as bend and drag folds.

The sedimentary rocks host mainly NW/SE striking veins with copper mineralisation, comprising e.g., chalcopyrite, chalcocite, sulfidic minerals, in combination with carbonates or quartz, as well as copper oxides (e.g., malachite) at the present-day surface. Processes, which lead to vein and ore formation and the possible tectonic influence are still not clearly understood. So far, the copper-bearing veins are mainly associated to the Variscan orogeny and hydrothermal influence. Field observations and structural measurements of stratigraphic bedding, fractures, and veins surrounding the Ouansimi mine are complemented with subsurface data, as well as transmitted and reflected light microscopy. Furthermore, microstructural observations are supplemented with cathodoluminescence microscopy.

This study will help to understand, if tectonic events beside the Variscan orogeny influenced the formation of veins and faults, as well as folds. Thus, the understanding of the regional geologic and tectonic processes of the Western Anti-Atlas region will be complemented.