Co-Ni-arsenide mineralisation in the Bou Azzer district (Anti-Atlas, Morocco): Genetic model and tectonic implications

The two main types of mineralisation in the Co-Ni-As Bou Azzer district, i.e., “contact” mineralisation” and “cross-cutting” structures have been re-defined based on new field, structural, textural mineralogical observations. orebodies consist elongated lenses massive Ni-Co-Fe arsenide minerals. These occur a core carbonate or siliceous gangue are almost exclusively located along contact between serpentinite quartz diorite intrusion. Vein system, cross-cutting different lithologies, is ore-bearing only segments with and/or mineralisation. orebody share rather similar history, starting Ni-rich stage (mainly expressed within mineralisation), followed by Co-arsenide recognised both styles, ending Fe-rich base metal sulphide stages. Detailed field observations, microstructural, tectonic, analyses led us to propose genetic model for ore district which was formed alteration transformation previously breccia levels composed (transformed gangue) magnetite/spinel Co-Ni minerals) fragments. Inversely, tectono-hydrothermal event controlled NE-oriented transtension generated vein associated certainly partial remobilisation reconcentration metals from because veins principally mineralised when crossing orebodies. We discuss possible temporal continuum styles: mineralisation, coeval serpentinisation (serpentine neoformation), related brecciated lenses, as an infill large fractures during transtensive tectonics. This has significant tectonic implications, favourable high-permeability environment formation, can be compared ophicalcic rocks developed context mantle exhumation detachment. Two textures differentiated mineralisation: i) Brecciated Massive Mineralisation, levels, ii) Laminated supposed form ancient mylonitic corresponding intensive deformation zones. Although geodynamic significance will not addressed this article, we alternative presence exhumed allows formation specific deposits.