Summary:
Deposit types
The deposits located on the Property are associated with the Proterozoic Birimian orogeny of West Africa. Most gold mineralization in the West African Craton is shear-zone-hosted and structurally controlled, with lithology having a minor, local influence. The mineralization developed in the Kiniero Gold District conforms to this general style of mineralization.
Generally, vein-hosted lode type mineralization of the Birimian-style is associated with regionally metamorphosed terrains that have undergone considerable deformation and polyphase intrusive events. Birimian deposits are typically strongly structurally controlled but are also commonly associated with rheological contrasts within and between different lithologies. Recent drilling at both the SGA and Sabali South deposits has indicated the lithostratigraphy as being key to how the differing lithologies support structural preparation at a local scale.
Gold mineralization is typically late-orogenic, medium-grade lodes which are strongly structurally controlled and located within quartz veins or in quartz-veined fracture zones with intermineralization intrusives. Structures can be classified from their textural development as to whether their origins are proximal or deep-seated. The principal structural trends have been identified through trenching and drilling and are also visible within the existing open pits. Exploration drilling has continued to target the main structural orientations with holes aiming to intercept the mineralization trends at a sub-perpendicular orientation.
Mineralization
Previous mining and more recent exploration indicate that the gold mineralization occurs in veins a few millimetres to tens of metres in width, with predominantly quartz-sulphide mineral assemblages and differing secondary minerals depending on the degree of alteration and/or overprinting. The veins generally take the form of composite anastomosed structures. At least three categories can be distinguished, corresponding to three consecutive stages of the hydrothermal process, and in turn, there is an extensive pervasive albitization event which overprints the earliest veining:
• Massive sulphide veins comprising pyrite and lesser chalcopyrite (with secondary chlorite, sericite and ± carbonate), which correspond to an initial high-temperature hydrothermal environment.
• Quartz-sulphide veins which cross-cut the sulphide veins (with secondary sericite and chlorite).
• Parallel, narrow (1 mm to 2 mm) quartz veinlets that are more tabular than the quartzsulphide veins and commonly occur as multiple sheets in the periphery and parallel to more significant massive sulphide and quartz-sulphide veins, e.g. the veinlets at Sabali South develop as local stockworks within more brittle host rocks and have well-developed alteration reaction boundaries.
A total of 47 gold anomalies have been identified on the Property (Figure 7.6), of which the following deposit clusters form the focus:
• Sabali cluster, including:
- Sabali North.
- Sabali Central.
- Sabali South (straddling the Kiniero/Mansounia boundary).
• Mansounia Central.
• SGA cluster, including:
- Sector Gobelé A (A, B, C) (SGA).
- Gobelé D. ? North-East Gobelé D (NEGD).
- East-West.
• Jean cluster, including:
- Jean East and Jean West.
- Banfara.
• Balan cluster, including:
- Derekena.
- West Balan.
In addition to the above deposits, legacy ROM, and low-to-medium grade stockpiles are also present.
Sabali Cluster
The Sabali North, Central, and South deposits occur within the same structural corridor and are broadly comparable in both their geological, lithological, and structural characteristics. From north to south there are, however, changes in the host/wall rock alteration with Sabali South being overprinted by an intense argillic alteration event, a distinguishing feature. It is noted that the observed changes in alteration might relate to vertical displacements of mineralized blocks within the corridor, rather than potential changes in character of mineralizing fluids.
Mansounia Central
The Mansounia Central deposit is located to the south to south-west of the Sabali South deposit, and had been previously segmented into three separate targets, namely the Mansounia North deposit, which now forms a part of the Sabali South deposit, the Mansounia Central deposit and the Mansounia South deposit. Mansounia Central represents a direct on strike extension of the Sabali South deposit, part of the much larger shear mineralized corridor, termed the “Sabali-Mansounia” Corridor.
SGA Cluster
The SGA Cluster of deposits are broadly geologically, structurally, and geographically related and share, in some instances, interrelated and overlapping exploration datasets. The SGA Cluster, comprised of the various Gobelé deposits, along with the Jean deposits, formed the focal point of early-exploration, development, and exploitation at the previous Kiniero Gold Mine.
Jean Cluster
Jean East and West
The Jean East and West deposits are situated immediately west of the various Gobelé deposits of SGA and were discovered at the same time as the Gobelé deposits. Jean East is characterized by thick mineralized subvertical structures elongated for approximately 500 m, trending 010°. This 010° trending structure at Jean East was mined, as well as the 350° striking mineralized structure at Jean West. The two mineralized structures at Jean are distinctly separated by a 030° trending fault.
Banfara
The Banfara deposit represents a steep sided worked out open-pit that targeted two mineralized structures, one trending north to south (a principal regional control) and dipping steeply to the west, and the other north-west to south-east dipping steeply to the east.
Balan Cluster
The Balan Cluster of deposits includes the Derekena, West Balan, Kobane, and Farabana deposits, four principal zones of mineralization which represents one the most continuous zones of mineralization yet delineated within the Project. The Balan Cluster is unique in that the mineralization has developed along east-north-east shear zones, a key strike trend in the Siguiri Basin, but which is secondary to the north-west to north-east structures which dominate the Kiniero Gold District.