Summary:
All the vein-hosted gold mineralization at True North is hosted within the Townsite Unit of the Bidou Lake Assemblage and within the SAM unit gabbro which intrudes the Townsite Unit. The Bidou Lake Assemblage forms a north-facing stratigraphic sequence of tholeiitic basalt to intermediate volcanic flows, dacite crystal tuffs and breccias overlain by well stratified felsic epiclastic rock interpreted to be of pyroclastic and sedimentary origin. The stratigraphic sequence is intruded by tholeiitic gabbro sills and dykes and felsic porphyry dykes.
Veins and Mineralization
According to Anderson (2008), shear-hosted veins include massive, laminated and brecciated varieties, commonly within the same vein, and typically pinch and swell along strike and down-dip. Thicker veins are associated with inflection points in the host shear zones, which suggests hydrothermal infill of dilational jogs.
Most of the shear zones are associated with fringing arrays of kinematically linked extension and oblique-extension quartz veins, which locally intensify into complex peripheral stockwork-breccia systems. Considering the geometry of the vein arrays, the vein textures indicate syn-kinematic emplacement under brittle-ductile conditions. Most deposits are arrays of sub-horizontal extension veins, which suggests emplacement accompanied by transiently supra-lithostatic fluid pressures.
In the True North deposit, the gold-bearing quartz veins occur mainly as either “16-type” shear zone veins or “38-type” tensional fracture stockwork veins or, where they intersect, as a combination of the two vein types. The 16-type appear to be fault fill veins with generally higher grades and more continuity, which are laminated with pressure solution seams (stylolites) and trend north-northeast.
The stylolites consist of intergrown pyrite-chlorite-tourmaline-muscovite. Compared to the 16- type, the 38-type are stockwork breccia veins that are wider and arranged in an en-echelon pattern along the strike and down the dip of the host gabbro unit, but gold mineralization is more irregular and grades difficult to predict. In some deposits, for example SG-1 and SG-3, the gold mineralized veins were intensely transposed during ductile deformation (Anderson, 2008), and presumably later in the SG-3 deposit.
Gold typically occurs as free grains associated with pyrite or as inclusions in pyrite. Gold grades tend to be highly erratic within individual quartz veins. The gold ores have high Au/Ag ratios of > 5:1 and low concentrations of copper, lead, zinc, arsenic, bismuth, boron, antimony and tungsten, as is typical for Archean lode-gold deposits.
Deposit Types
The association of gold at True North with quartz-carbonate veins in brittle-ductile shear zones and laterally extensive hydrothermal alteration zones indicates that the deposits represent epigenetic mesothermal lode gold-type (Poulsen et al., 2000) or orogenic-type gold mineralization (Groves et al., 1998).
Such gold deposits form from metal-bearing fluids generated during accretionary processes and prograde regional metamorphism at depth in greenstone belt terrains. In this model, the resulting fluids migrate and are channeled upward along transcrustal fault systems to subsidiary shear and fracture structures developed in the middle to upper crust. Gold is deposited in quartz carbonate veins as a result of pressure-temperature, pH, and other physiochemical changes, phase separation and fluid-rock reactions. The reactions commonly involve sulphidization of precursor oxide, carbonate and silicate minerals and mineral assemblages.
Commodity Production
During the year ended December 31, 2023, the Company completed the clean-out of the mill that had started in December 2022, recovering 478 ounces of gold.
| Commodity | Units | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
|
Gold
|
oz
| ....  | .... | .... | .... | 5,653 | 7,299 | 27,877 | 10,187 |
|
Silver
|
oz
| | | | | | | 3,174 | 853 |
|
Gold Equivalent
|
oz
| | | | | | | 27,919 | 10,199 |
All production numbers are expressed as metal in doré.