Summary:
The Project includes the Box and Athona gold deposits, as well as other gold occurrences discovered during historical exploration.
Deposit Type
The Box and Athona gold mineralization shows many characteristics which support their classification as orogenic gold deposits. These include a regional association with an orogenic fold belt (Trans-Hudson Orogen), quartz-vein or fracture dominated ore systems within a brittle structural regime, and association with sulphides (albeit very low levels 0.5%). A distinctive first-order, deep-crustal structure is not obviously apparent at Goldfields, however the Black Bay fault provides a possible candidate that may have acted as the primary fluid pathway. The alteration assemblage at Box and Athona is atypical for orogenic gold deposits which may suggest the deposits represent a hybrid model. The deposits closely resemble an oxidized intrusion-related (porphyry) gold setting which was largely based on the interpretation that veining was coeval with emplacement/formation of the Mine Granites, and the alteration zonation observed is typical of gold-rich porphyry style deposits. Petrographic study indicates the gold mineralization is epigenetic, post-dating the mine granites and an earlier hematite alteration event. This conclusion is supported by a structural analysis of the Box deposit by Roberts (1988) that demonstrated that the mineralized vein system was emplaced during deformation that affected (postdated) the emplacement of the host Mine Granites. Furthermore. the age and erosion-level of the country rocks in northern Saskatchewan suggest preservation of a porphyry-system would be unlikely. Further study involving characterization of the ore fluids and alteration assemblages may assist in better defining the deposit model.
Mineralization
The Box and Athona deposits, located 2 km apart, share many similarities which suggest a close genetic association. The Box deposit lies on western limb, and the Athona deposit within the hinge, of a major open synclinal structure termed the ‘Goldfields Syncline’. This fold is an open, upright NNE trending, shallowly plunging synform, the closure of which is defined by changes in orientation of the main regional foliation.
Mineralization characteristics at Box and Athona are similar, comprising quartz vein sets hosted within a metamorphosed and hematized leucogranite, respectively termed the Box and Athona “Mine Granites”. Protoliths of these units are uncertain. Early models for the origin of the Box Mine Granite included an intrusive model and a metasedimentary model. The Box and Athona Mine Granites are intrusives, formed as nearly in-situ melts in the presence of metasomatic fluids.
Irrespective of the genetic model, the Mine Granites are the primary hosts to gold mineralization, likely due to a relatively brittle response to deformation, in contrast to more ductile hanging- and footwall lithologies. This resulted in the preferential development of pervasive quartz veining in the granite hosts and associated precipitation of sulphides and gold. The immediate hangingwall (1 to 3 m) to the BMG comprises sheared metasedimentary gneisses and schists that may contain high densities of quartz veins, and some auriferous veins, however these are not continuous across the BMG hangingwall surface and not present in sufficient size or density to justify further targeting.
Mineralization at both the Box and Athona deposits is strongly structurally controlled and associated with a network of milky white quartz veins that have an average N-S trend and moderate to steep westerly dips. Vein population subset orientations include NNW, NNE and WNW trends with the NNW set dominant at Box and the NNE set dominant at Athona.
Gold is typically associated with early coarse pyrite in quartz veins, and is commonly found in fractures within pyrite, at pyrite-quartz grain boundaries, and less commonly as small spherical inclusions within pyrite and in adjacent vein quartz. Partial or complete replacement alteration and oxidation of pyrite has produced acicular hematite which is commonly intergrown with gold that once occupied fractures in pyrite or was included in the pyrite. Gold is also less commonly found associated with sphalerite, chalcopyrite and galena within fractures in pyrite, which may represent a second gold mineralization phase.