Summary:
The Project consists of the Pick Lake Deposit and the Winston Lake Deposit.
The Project occurs in Archean rocks of the Southern Superior Province which forms the core of the Canadian Precambrian Shield. It consists of a collage of Archean greenstone belts, that coalesced between 2.72 and 2.68 Ga and were intruded by a complex system of granitoid rocks that were exhumed by approximately 2.48 Ga (Percival, 2007). The Superior Province is particularly well endowed with gold, copper-zinc and nickel deposits, as well as other commodities in lesser amounts.
The Pick Lake and Winston Lake deposits and all nearby prospects are examples of metamorphosed volcanogenic massive sulphide (VMS) deposits, that form in collisional oceanic tectonic environments in areas of localised rifting (Lodge et al., 2014).
The Pick Lake deposit belongs to the bimodal mafic volcanic sub-type, also known as Canadianshield or Noranda-type VMS deposits. The deposits of this sub-type are characterised by dominating of the mafic volcanics with the felsic volcanic rocks constituting less than 25% of the sequence.
PICK LAKE DEPOSIT
The Pick Lake deposit occurs at the extreme western edge of the Winston-Big Duck Lake sequence of volcanic rocks, approximately 35 metres above a granitic contact. Aeromagnetics within the Project area depicts a distinctive “V” shaped sequence of magnetic and non- magnetic units converging to a northern “V” apex and appears remarkably similar to the aeromagnetic character of the older Archean Warriedar Fold Belt in Western Australia which hosts the Golden Grove VMS deposits.
The Pick Lake deposit occurs as a large sheet like zone of massive sulphides within a series of bedded pyroclastic rocks. Hydrothermal alteration exists in both footwall and hanging wall rocks resulting in varying assemblages of quartz, cordierite, biotite, anthophyllite, garnet, chlorite and sericite with minor disseminated sulphides. The hydrothermal alteration zone appears to be spatially related to the Winston Lake deposit; recent structural mapping provides evidence that Pick Lake and Winston Lake may be hosted within the same stratigraphic horizon.
The Anderson showing, located near the southeast shore of Winston Lake, appears to be the surface expression of the Pick Lake deposit. This is a rusty pyritic weakly altered series of bimodal volcanics. Massive sulphides of the Pick Lake deposit occur from approximately 300 m to 1200 m vertically and over a strike length averaging 250 m. The lower portion of the deposit appears to increase in strike length to approximately 500 m. The deposit strikes at 20 degrees and dips to the east at 50 degrees. The thickness of the deposit is generally between 2 and 4 m; however, locally it is up to 14 m.
Sulphide mineralisation is generally very consistent, composed of a fine-grained mixture of sphalerite (50-80%) and pyrrhotite (5-35%) with minor chalcopyrite (0-5%) and pyrite (0-3%). Commonly contained within the sulphides is 5-10% of quartz inclusions, that are represented by the rounded grains up to 3 cm in size and, less commonly, by veins, cutting the massive sulphide mineralisation. Mineralisation also contains inclusions of the host volcanic rocks (1-3%) which are commonly intensely foliated and altered to chlorite-biotite schists. Random orientation of the foliated inclusions indicate that deformation and displacement of the sulphide mass has continued after main peak of metamorphism. Intensity of foliation fabrics increases toward the contact of the massive sulphides, which are typically sharp. The main Zn mineral is sphalerite.
WINSTON LAKE DEPOSIT
The Winston Lake deposit lies at the top of the Winston Lake sequence within cherty exhalite and altered felsic-to-intermediate laminated ash tuff. In places, gabbro forms the hanging wall of the deposit. The footwall consists of altered mafic flow rocks and felsic-to-intermediate volcaniclastic rocks which are underlain by altered quartz and feldspar porphyritic rhyolite and feldspar pyritic basalt with intercalated sulphide-rich, bedded, tuffaceous rocks which, in turn, are underlain by the "Main" quartz feldspar porphyry which is intruded by gabbro and pyroxenite.
High copper values occur at the flanks and top of the alteration "pipe" with the core of the pipe containing relatively depleted copper values. The most common forms of ore are finely banded sphalerite and pyrrhotite and massive-to-coarsely banded sphalerite and pyrrhotite with minor pyrite and chalcopyrite and up to 45% of sub-angular mafic and felsic fragments averaging 3 cm in diameter. The north-striking and 50 degrees eastwardly dipping deposit has a strike length of 750 m and width of 350 m. It has an average true thickness of 6 m and is open to depth.
Hydrothermal alteration, confined to the Winston Lake sequence, and later metamorphism of altered rock have resulted in assemblages of cordierite, anthophyllite, biotite, garnet, sillimanite, staurolite, muscovite and quartz coincident with an increase in iron, magnesium, and potassium and a decrease in sodium and calcium. Zinc content is directly proportional to the intensity of alteration. The recognition of metamorphosed hydrothermal alteration played an important role in the discovery of the Winston Lake deposit (Turcotte and Verschelden, 2013).
Metamorphosed mafic volcanic rocks in contact with the Zenith Gabbro were observed to have unusual mineral assemblages, including the presence of anthophyllite, cordierite and garnet. These rocks were also found to be enriched in Zn, K, Mg and Fe, and depleted in Na and Ca, which defined a zone of hydrothermal alteration associated with a downhole pulse EM anomaly. Drilling of this EM anomaly led to the discovery of the Winston Lake deposit. Further detail on the hydrothermal alteration of the rocks within the Winston Lake Assemblage was obtained by Osterberg (1993). Widespread distribution of altered volcanic rocks have been noted at the Pick Lake deposit, as well as the Rain Mountain, Trail and Ciglen showings (Severin et al., 1991).