Summary:
The Project’s mineralized zones have the characteristics of epigenetic, mesothermal quartz vein style gold deposits with an overlying gold-bearing saprolite. This type of mineralization is the most important type of gold occurrence in West Africa and is commonly referred to as the Ashanti-type.
Sewum Zone
The Sewum West and South prospects are found along the eastern contact of a thrust-bounded volcanic sliver, outcropping 6 km to the east of the Boin Zone on the NS. The gold mineralization is associated with late D2 to D4 deformation phases. It is structurally controlled within, and adjacent to, late graphitic faults focused on the margins of poly-phase quartz veins within faults. The veins developed along the axial planes of hinges and limbs of earlier hanging wall D3 drag folds ± intrusives.
The host rocks at Sewum include interbedded carbonaceous siltstone and sandstone (turbidite). The sediments have been regionally deformed to greenschist facies, are steeply dipping, and typically strike north-northeast (30º) parallel to the regional structural grain. A steeply dipping dolerite dyke 3 km long and up to 500 m wide has been intersected in the drilling and acts as an important host to gold mineralization in the Sewum area.
Three styles of mineralization have been identified at Sewum:
- Disseminated arsenopyrite associated with quartz veining and silicification in sheared sediment, e.g. Sewum Shear Zone.
- Quartz – sericite – carbonate replacement of sheared dolerite and sediment localized along moderately (40°) dipping shears hosted within dolerite, e.g. Sewum Ridge Top Shears (SRTSZ).
- Brecciated and stockworked sediment and dolerite developed at the margin of the dolerite dyke and replaced and in-filled by quartz-sericite ankerite and minor sulphides, e.g. Checkerboard Hill, East Contact Zone (ECZ), and West Contact Zone (WCZ).
Boin Zone
The Boin Shear Zone is formed in the west hanging wall of this major second-order, west-dipping, thrust contact between mafic volcanic ±volcaniclastic sediments which over-thrust turbidites to the east. The whole contact is expressed as a 10 to 30 m wide graphitic shear zone, which trends 025° to 040° and dips west 30° to 70°. The Boin thrust is an early, regionally second-order splay or replication off the main basin-boundary contact further to the west. Multiple sets of crosscutting fabrics, veins, and faults have been recorded within the core and trench logging. The gold is mostly found in the hanging wall quartz zone and is characterized by massive 20 to 30 m wide zones of intensive quartz veining cut and fractured by late, graphitic faults.
Nyam Zone
The Nyam Zone strikes over a distance of 1.8 km, hosted by altered phyllite, 200 to 300 m west of the interpreted position of the second order NS. The zone of mineralization lies in the hanging wall of a northeast-striking shear that dips 70º east and is up to 30 m thick. Nyam mineralization is part of a continuous 15 km strike length of gold prospects on the Project from Nyam southwest through Kojina Hill to Sewum in the south. An extensive envelope of weak gold mineralization (more than 0.25 g/t) dips sub-vertically and strikes 030°.
Mineralization at the Nyam Zone is composed of veined and brecciated sediment and phyllite cemented by quartz, carbonate (ankerite), and albite and has been traced continuously in trenching and drilling for over 2 km along strike.
Kwakyekrom Zone
The Kwakyekrom Zone is located 3 km south of the Nyam Zone and is interpreted to be related to the extension of the same structure. Drilling has tested the Kwakyekrom Zone over a strike distance of 1.3 km and to a depth of approximately 150 m. The zone is hosted by altered phyllite, 700 to 800 m west of the interpreted position of the second order NS structure. The phyllite has been intersected by metre-scale dolerite dykes similar in composition to the larger intrusive bodies encountered at Sewum.
Kwakyekrom mineralization is part of a continuous 15 km strike length of gold prospects on the Project from Nyam southwest through Kwakyekrom to Sewum in the south. Gold mineralization is hosted in a series of sub-parallel zones (more than 0.20 g/t) ranging in width between 5 and 25 m and dipping sub-vertically and striking 030°.
Kwakyekrom mineralization is associated with sediments showing intense ductile strain, with centimetre- to metre-scale quartz veins focused within brittle-ductile deformation zones. Additionally, sediment-dolerite contacts are often the site of quartz veins and variable gold mineralization.