Summary:
The Deposit is a turbidite-hosted orogenic gold deposit hosted within a sequence of alternating argillites and greywacke metamorphosed to greenschist facies. The metasedimentary units on the Property are folded into the tight, gently east-plunging Upper Seal Harbour Anticline and gold mineralization has typically been deposited at various positions and times during the fold formation process. Veins, which form during deformation, occur in three major geometries commonly referred to as reefs: saddle reefs, leg reefs, and spur reefs. The Deposit contains all three types of reefs outlined above but is also characterized by mineralization within the argillite forming the Belts. Because the Deposit contains saddle, leg, and spur reefs, and often has gold mineralization within the argillite hosting the veins, it has the potential to contain significantly more gold resources than deposits of a similar style that contain gold only within the quartz veins (reefs) themselves. The trace of the Upper Seal Harbour Anticline transects the Property and is found near the Dolliver Mountain prospect 2 km to the west of the Deposit, demonstrating that the structure which hosts gold continues for several kilometres.
At the Deposit, the Goldenville Formation consists of alternating greywacke and argillite beds with an approximate true thickness of 950 m. The base of the stratigraphic sequence intersected in the BR Gold System consists of roughly 325 m of alternating greywacke and argillite, with varying proportions of both rock types, ranging in thickness from less than 1 m up to 10 m.
The structure of the Project area is dominated by the Upper Seal Harbour Anticline. The anticline folds all levels of stratigraphy observed in core and underground to form an upright, tight anticline that plunges 20° eastward. The enveloping surface to bedding also dips moderately eastward at 20°. Younging is upward, orthogonal to the hinge, and limbs of the fold.
Gold mineralization at the Deposit occurs in both quartz veins and within the argillite that hosts the veins, as well as within the rocks adjacent to the modelled argillites and quartz veins, including both lesser argillite with greywacke. Disseminated, euhedral arsenopyrite is pervasively associated with gold mineralization, and is commonly observed within the host rock and is usually present in mineralized quartz veins. Other sulphides associated with mineralized quartz veins are pyrrhotite, chalcopyrite, pyrite, and minor amounts of sphalerite and galena. Wall rock generally contains more pyrrhotite and arsenopyrite than directly associated quartz veins. Gold bearing quartz veins are stratabound with lesser discordant quartz veins and vein arrays (Figure 7-5). Native gold is nuggety in nature, and grains range from microscopic up to several centimetres in size and is found in all rock types with visible gold generally associated with quartz veins. Within quartz veins, gold is present as free gold in quartz, and within arsenopyrite grains, along grain boundaries and internal fractures, and is non-refractory in nature. Native gold also occurs as a disseminated phase in altered argillite and argillite/greywacke intervals adjacent to and separate from quartz veins, demonstrating its association with both quartz veins and the altered wall rock.
At the deposit scale, the veins form a swarm and are clearly located in the flexure zone (hinge and adjacent limbs) of the Upper Seal Harbour Anticline. The gold bearing veins are found in a 175 m to 275 m wide envelope centred on the axial surface. The veins occur mostly on the limbs of the fold, but also in the hinge, and all are hosted by turbiditic metasedimentary rocks consisting of greywacke and argillite.
Gold bearing quartz veins occur as both stratabound and cross-cutting entities and are most prevalent within BP stratigraphy, occurring approximately 80 m north or south of the Upper Seal Harbour Anticline’s axial surface.
High-grade gold mineralization at the Deposit occurs in both quartz veins and host argillite. These high-grade zones are BP and generally continuous around the fold hinge and down the north and south limbs. These mineralized zones are referred to as Belts. Sixty-eight Belts have been modelled within the Deposit and are referred to as Higher-Grade Belt within the model. A more disseminated, generally lower-grade, style of mineralization occurs in the wall rock adjacent to the quartz veins and can extend several metres outward from and between Higher-Grade Belts. These are referred to as Lower-Grade Domains and can include disseminated gold mineralization within altered, sulphide (arsenopyrite) bearing wall rock including greywacke and argillite, gold bearing quartz sulphide veins of variable orientation that do not correlate geometrically to adjacent HigherGrade Belts.
Turbiditic rocksin the hinge zone of the Upper Seal Harbour Anticline have been variably altered with carbonate, sericite, sulphide, tourmaline, and chlorite assemblages that post-date growth of regional metamorphic mineral assemblages (Roy & Labelle, 1990). The nature of alteration varies as a function of lithology and proximity to mineralization.
The gold mineralization observed in both core and microscopically is reflected in the multi-element geochemistry in the Deposit. Preliminary evaluations of the assay database illustrate that there are strong Au-As-S-Pb-Cd associations within the database, reflective of the mineralogy outlined above. There are also local enrichments in Zn, Cu, Fe, Ni, and Co reflective of the presence of sphalerite, chalcopyrite, pyrite and pyrrhotite.