The Cumberland deposit is on the west-limb of the Eskay anticline approximately 12 km south of the Lulu Zone on the southern wall of the Sulphurets Creek valley. The mineralized zone occurs near the Eskay Rhyolite-Willow Ridge mafic unit contact (Figure 8), the same stratigraphic position that hosts the Eskay Creek deposit. This suggests that the Cumberland VMS system formed during the same time period as Eskay Creek. The presence of the auriferous sulphide minerals at the rhyolite-basalt contact suggests Au prospectivity on the west limb of the Eskay anticline continues to the south.
The Eskay Rhyolite-Willow Ridge contact was intercepted by drill hole CBL05-06 (Figure 9). The interval 28.66-33.53 m is a mudstone with sparse flattened black pebbles (< 5 mm). Historic assays from this mudstone interval range from 1.00-1.97 g/t Au. Rhyolite breccia replaced with semi-massive sulphide minerals occurs from 35.55-43.07 m. Historic assays from the mineralized rhyolite breccia range from 0.20-7.83 g/t Au. The stratigraphic position of the mudstone and rhyolite breccia along the west limb of the Eskay anticline is consistent with a VMS hydrothermal system at the Contact Mudstone horizon.
C10 were a significant focus of the 2020 field program. Relogging and sampling of historic drill core, reconnaissance mapping, and induced polarization (IP) investigations were conducted. Historic drilling at C10 intercepted numerous auriferous intervals grading as high as 99.4 g/t, with numerous intercepts in the 1-10 g/t range.
Re-examination of historic drill indicates that host rocks at C10 are stratigraphically correlated with Betty Creek Formation host rocks at TV and Jeff, with both the Brucejack Lake and Johnny Mt Dacite Mineralized Zones hosting gold at C10 (Figure 20). Rocks at C10 are more metamorphosed and deformed than further north (Figure 21), however relict primary rock textures and mineralogy, coupled with lithogeochemical analyses have confirmed the andesitic to dacitic composition of host rocks at C10. Examination of the topographic expression using 3-D modelling shows that C10 lie along the newly identified east limb of the Eskay anticline, forming a mineralized trend with Jeff and TV to the north. C10 is immediately west of a topographic lineament interpreted to be the west-dipping thrust fault that juxtaposes the Eskay anticline over the proposed Eastern anticline.
Induced polarization investigations conducted in 2020 show chargeability anomalies that correlate with known mineralization (Figure 22), and suggest that mineralization may be more abundant to the south of historic drill holes.
The C10 area will be a major focus of the 2021 program, with a Skytem survey, followed up by detailed geologic mapping, and ultimately drilling of promising IP chargeability anomalies.
Reconnaissance mapping, sampling, IP investigations, and relogging of historic drill core SH-2 was conducted at Spearhead in 2020.
Spearhead is a mudstone-hosted VMS deposit located approximately 1 km northeast of Red Lightning. Mudstone with semi-massive sulphide mineralization outcrops on the surface forming a SE-NW trend extending approximately 150 meters (Figures 23 and 24). Past surface sampling encountered grades of 2-4 g/t along the mineralized outcrop. Surface investigations and examination of drill core SH-2 show that Spearhead is hosted within felsic volcanic rocks possibly belonging to the Bruce Glacier felsic unit of the Upper Hazelton Group. Results from the limited sampling program in 2020 did not return any significant values for precious metals. An IP survey of Spearhead conducted in 2020 shows a chargeability extending down-dip from the mineralized horizon that outcrops on the surface (Figure 25). A detailed mapping and sampling program will be conducted at Spearhead in 2021.
Red Lightning is a gabbro-hosted magmatic Ni-Cu-Au-Pd deposit emplaced within Betty Creek Formation intermediate rocks. The 2020 field program included relogging three representative drill holes from Red Lightning, RL-3, RL-4, and CR06-86. These holes are characterized by gabbro intruded into contact metamorphosed Betty Creek Formation andesite and dacite.
The gabbro, andesite, and dacite are greenschist metamorphosed, however the gabbro retains a holocrystalline texture and much of its primary mineralogy of augite and plagioclase. The gabbro has zones of silicate-sulphide immiscibility with sulphide minerals grading from disseminated to massive textures. Sulphide mineralogy is dominated by pyrrhotite and chalcopyrite, with sphalerite and Ni-sulphides as accessory minerals (Figure 26). The gabbro displays distinct chilled margins at contacts with the Betty Creek Formation, and none where basaltic dikes cross-cut the gabbro, indicating the gabbro was emplaced after the Betty Creek Formation and before the cessation of basaltic volcanism. The resulting relative age of the gabbro places the intrusion during the period when VMS systems were active, suggesting the gabbro intrusion at Red Lightning may represent one of the rift-related magmatic intrusions that drove VMS hydrothermal systems.