Summary:
Deposits within the Back River District are characterized as banded iron formation-hosted gold deposits, which are structurally and stratigraphically controlled with gold mineralization predominantly hosted in sulphide-bearing oxide-iron formation.
The Goose Project hosts a total of 12 gold deposits with current Mineral Resource estimates. Six of these are hosted within the Goose Claims Group: the Umwelt, Llama, Goose Main, Echo, Nuvuyak, and Goose Neck South deposits. An additional six deposits are hosted within the George Claims Group: the Locale 1, Locale 2, LCP North, LCP South, Tupiq, and GH deposits
Mineralization
Gold mineralization is primarily hosted within oxide iron formation, and is spatially correlated with discrete high strain zones, F2 fold hinges and short limbs, lithological contacts, and quartz-feldspar porphyry dykes. Mineralization is commonly developed in fold axial planes and sub-parallel high-strain zones within limbs of F2 folds.
Gold is strongly associated with sulphide minerals, preferentially arsenopyrite, pyrrhotite and pyrite. Native gold may occur as visible grains, along fractures within sulphides, or within chlorite or amphibole/hedenbergite altered iron formation.
Sulphide mineralization is interpreted to have occurred during two distinct events, both of which are attributed to D2. An earlier event involved pyrrhotite and pyrite partially replacing magnetite bands and amphiboles, whereas the later event introduced the gold, and coarse arsenopyrite, and remobilized and deformed the early phase of pyrrhotite and pyrite. Semi-massive pyrrhotite and coarse-grained, subhedral arsenopyrite, are both strongly correlated with gold.
Pyrrhotite and pyrite associated with gold mineralization often occupy extensional features such as discrete extension veins and associated vein arrays, which frequently extend beyond individual beds or fold hinges. Sulphide-filled extensional features occur with greater frequency near zones of elevated gold mineralization. Pyrite is more common than pyrrhotite at shallower depths, though both sulphides display similar textural habits.
Visible gold occurs as very fine disseminations in chlorite and amphiboles proximal to, and sometimes along fractures within, coarse, subhedral arsenopyrite crystals. Gold is occasionally disseminated in quartz ± chlorite veins. Elevated concentrations of arsenopyrite exhibiting larger crystal size and a higher degree of euhedral crystallinity generally correlates with higher gold grades. Quartz ± chlorite veins rarely host scattered grains of arsenopyrite, minor patches of pyrrhotite, and secondary pyrite.
Quartz-feldspar porphyry dykes can contain evenly disseminated, medium-grained, euhedral arsenopyrite but typically do not contain gold, except when cross-cut by gold bearing quartz veins, commonly at dyke-wall rock contacts. Wall rock proximal to dyke contacts often hosts scattered arsenopyrite grains.
Trace to minor chalcopyrite, typically associated with pyrrhotite, is present in post-mineralization carbonate veins hosted in phaneritic gabbroic dykes of the Mackenzie Group.
Key Deposit Characteristics, Goose Claims Group
Mineralization occurs within the lower iron formation in well-defined structural corridors and is spatially associated with lithological contacts. Gold mineralization is strongly correlated with tension vein filling semi-massive pyrrhotite, pyrite, and coarse-grained arsenopyrite.
Umwelt
Hosted in a thickened antiform hinge and east-dipping short limb. The antiform trends approximately 125° and plunges approximately 25°south, with an axial plane dipping to the east at about 65°. A parasitic fold originating from the antiform hinge near surface rakes at an oblique 20° angle to the axial plane plunging moderately to the southeast.
High-grade mineralization is concentrated in the thickened portion of the antiform hinge, and along the parasitic fold on the short limb. Mineralization is primarily concentrated within the lower iron formation, with minor mineralization occurring in the surrounding metasedimentary units.
Llama
Hosted in the thickened antiform and limbs of a fold couplet, with synforms on each side of it. The Llama deposit trends at about 150° and plunges at approximately 20°, with an axial plane dip of 75° to the east.
Mineralization is primarily concentrated within the lower iron formation. High grade mineralization is concentrated in the thickened portion of the antiform hinge, and along the parasitic folds on the limbs.
High grade zones are characterised by abundant, medium to coarse grained euhedral or semi-massive arsenopyrite, commonly rimmed by pyrrhotite and associated with sheared quartz veins and pervasive chlorite. Pyrrhotite becomes significantly more prominent as the gold-mineralized zone plunges to the southeast.
Goose Main
Hosted within a tightly folded, antiform with an axial trace trending approximately 295° and plunging approximately 25° to the northwest.
Gold mineralization is associated with D2 structures, specifically discordant quartz veins that are commonly boudinaged and transposed parallel to S2 foliation.
Mineralization is primarily concentrated within the lower iron formation, with lesser mineralization developed within the deep iron formation, and upper iron formation.
Echo
Hosted in the fold hinge of an open F3 fold on the southern limb of the Goose Lake synclinorium. The dip of the limb is approximately 75° to the south, and the F3 axial plane trends 350° dipping approximately 75° to the east. The resulting fold hinge plunges towards 135° at about 65°.
Mineralization is primarily concentrated within the lower iron formation. Pyrrhotite is the dominant gold-associated sulphide at Echo. Oxide iron formation thickness increases with depth to approximately 15 m.
Nuvuyak
Hosted in an isoclinal F2 antiform re-folded by F3. The deposit has a fold axis trend of 300° plunges 30° towards NW, with an axial plane dipping 78° east. The fold is interpreted as the down-plunge continuation of the Goose antiform and lies with in the core of the Goose Lake synclinorium.
Mineralization is primarily concentrated within the lower iron formation, and shows a close spatial association with the quartz-feldspar porphyry dyke.
High-grade mineralization is associated with shearing, with an increased abundance of deformed quartz veins overprinted by arsenopyrite and pyrrhotite.
Goose Neck South
Hosted in the northwest-southeast striking northern limb of the macroscale Goose Lake synclinorium. The limb is dipping at 88° toward 200° with some local reversal where bedding is dipping sub-vertically north-northeast. Parasitic folding is present throughout the deposit.
Mineralization is primarily concentrated within the lower iron formation. Pyrrhotite is the dominant sulphide, exhibiting semi-massive, tension gash, and tension array fill habit. Mineralization is associated with localized parasitic folding overprinted by ductile shearing and associated cm-scale quartz veins.
Deposit Dimensions
Umwelt - 1,700 x 200 x 15 m; Llama - 1,900 x 150 x 10 m; Goose Main - 700 x 460 x 15 m; Echo - 450 x 370 x 6 m; Nuvuyak - 450 x 250 x 8 m; Goose Neck South - 400 x 350 x 6 m.
George Claims Group
Gold mineralization at the George Claims Group has similar depositional styles as those observed throughout the Back River District. However, the structural corridors at George are less well-defined than those at the Goose Claims Group. Gold mineralization is typically hosted in oxide iron formation, occurring in three distinct fold belts, George belt, Fold Nose belt, and Lookout Hill belt, with little continuity exhibited between these discrete mineralized domains.
Deposit Dimensions, George Claims Group
Locale 1 - 1, 350 x 300 m ; Locale 2 - 980 x 500 x 4 m; LCP North - 680 x 180 x 3 m; LCP South - 520 x 240 x 3 m; Tupiq - 540 x 140 x 4 m; GH - 650 x 250 x 3 m.