The deposits are characterized by multiple quartz and quartz–carbonate vein sets and stringers. Vein arrays occur in the east limb, fold hinge (or fold axis), and west limb lithostructural domains. Arsenopyrite and pyrite tend to be late, and are concentrated near the margins of the veins or in cross-cutting stringers.
Faults reactivated during the D1 and D2 regional deformation events provide the structural control on the mineralization.
Gold mineralization is associated with thrust faults or shear zones with brecciated, banded, sheared quartz veins and boudins within highly silicified zones.
Mineralized bodies form as subvertical, or slightly inclined to the east, and consist of lenses, quartz stockwork and/or quartz–carbonate veins. The preferred emplacement is on the fold hinge or the limbs (EMZ, Tassiri, Gourara) or along shear corridors (Gossey, Korizena, Sokadie).
Essakane (EMZ, Essakane Nord, Gourouol)
The EMZ deposit is about 3,000 m long. Mineralization has an average thickness of approximately 200 m. Mineralization has been intercepted at 600 m vertically below surface; however, the deposit remains open at depth and along strike.
The Essakane Nord and Gourouol deposits are situate immediately north of the EMZ deposits. The Essakane Nord deposit is mined out. The mineralized zone was approximately 400 m in length, averaged about 40 m in thickness, and was intercepted to 200 m depths below surface. The Gouro ........