Cobalt-nickel-copper arsenides, sulfarsenides and sulfides of Bou Azzer (Anti-Atlas - Morocco): Lithological and structural controls

Abstract

The Bou Azzer-El Graara inlier is famous by its Co-Ni deposit associated to a Neoproterozoic ophiolitic complex. This paper aims to present results from three sectors, the Bou-Froukh, the Aghbar, and the Ait Ahmane deposits. Geological investigations (Leblanc, 1975; Saquaque, 1989) and recent radiometric data (Admou 2013) allow recognizing three major formations in the Bou Azzer Inlier: The Bou Azzer group; the Tiddiline Fm., and the Ouarzazate group. These Neoproterozoic formations have undergone the Pan-African events which take place in two episodes. The B1 phase is materialized by the development of a general NW-SE flow cleavage recorded in the Bou Azzer group, whereas the B2 phase is characterized by a fracture cleavage expressed in the Tiddiline Fm., along with a network of reverse faults and sinistral strike-slip faults crossing the entire region, they are considered to be inherited from the B1 phase and then replayed in the form of sinistral strike-slip faults during the B2 phase, and staked by quartz- carbonate lenses, making them vents for mineralizing fluids. These faults played a significant role in the Bou Azzer district's mineralization by enabling the emplacement of arsenides vein mineralization. The mineralization primarily consists of triarsenides, sulfoarsenides, and sulfides, hosted by quartz and quartz-carbonate veins.