Summary:
The Colomac property lies within the Indin Lake Supracrustal Belt, a 300 km long (2,000 km2 ), NNE-trending, elongate area of Archean volcanic and sedimentary rocks belonging to the Yellowknife Supergroup (Frith, 1986). The belt lies within the southwestern Slave Structural Province, 30 km east of the boundary with the Bear Province (Morgan, 1992).
Two main gold deposit models are relevant to most of the mineral deposits and showings on the Property: 1) greenstone-hosted quartz-carbonate vein (“GQCV”) deposits; and 2) BIF-hosted deposits. Both types are lithology-based subtypes of orogenic gold deposits. Additionally, the Andy Lake and the Treasure Island area were interpreted as an intrusion-related gold system (“IRGS”) and volcanogenic-related gold mineralization, respectively, although the latter still needs to be demonstrated. Until then, Treasure Island is classified within the GQCV model.
The Hewitt Lake Group is conformably overlain by the Leta Arm Group, which consists of NNE-trending belts 1 to 4 km thick and 5 to 30 km long. It comprises a heterogeneous sequence of submarine to subaerial, tholeiitic, and calc-alkaline, mafic to felsic volcanic rocks intruded by synvolcanic gabbro to quartz diorite intrusions. It has a greater proportion of intermediate to felsic volcanic and volcaniclastic rocks than the Hewitt Lake Group and hosts numerous gold deposits, including the Colomac deposits, as well as polymetallic and base metal prospects.
Colomac
The Colomac Area is underlain by a 4 km thick belt of lower greenschist-grade intercalated mafic-intermediate flows, intermediate-felsic volcanics and intermediate intrusive rocks, bounded by metasedimentary rocks to the east and west (Cohoon et al., 1991a and b) . A multiphase, synvolcanic intrusive complex (about 2 km x10 km at the surface) intrudes the volcanic rocks on the west side of Baton Lake, within 800 m of the western volcanic-sedimentary contact. The host strata and synvolcanic intrusive complex is strongly deformed, and mafic units have a steeply-dipping foliation and a steeply-plunging lineation. The sill complex strikes north-northeast and dips steeply east, subparallel to the host strata.
Mineralization at the Colomac Main deposit has been identified along an approximate 6.7 km strike length of the Colomac sill and has been divided into a number of somewhat arbitrary zones.
The quartz veins average from less than 0.5 cm to 10 cm thick, and they commonly contain little (less than 5%) carbonate. They are generally co-planar, with variable trends and relatively shallow dips of 20° to 40°. Shallow-dipping veins become steeply dipping within shear zones and become part of the shear veins, which may approach up to 1.0 m wide.
Goldcrest
The Goldcrest deposit is located approximately 1 km west and 2.25 km south of the Colomac Main deposit. The mineralized zone is very similar to the Colomac sill deposits, where quartz veins cut competent, fractured quartz diorite, but the mineralization and veining are more erratic at Goldcrest (NWT Geoscience Office, 2012b).
Grizzly Bear
The Grizzly Bear deposit is underlain by greenschist-grade mafic volcanic and sedimentary rocks. The mineralized zone is subparallel to the strata, trending northeast, and contains anomalous hydrothermal alteration, sulphide mineralization and gold (NWT Geoscience Office, 2012c). The mineralization consists of quartz veins and veinlets, with disseminated sulphides and native gold.
Mineralization has been intersected over a cumulative length of 1,200 m and has been tested to 200 m below surface. True widths of the mineralized zones vary from 5 m to 20 m. The mineralized zones strike 040° and dip steeply to the southeast. The mineralization is open to depth and along strike to the north but appears to peter out southward.
24 Deposit
The 24 deposit is located along a north-trending contact between volcanic rocks to the east and sedimentary rocks to the west. The 24 deposit is characterized by intense quartz flooding within interbedded andesite and greywacke silts tone. Quartz flooding occurs as parallel “veins”, with a strike length varying from 1.5 m to 7.5 m and widths from 0.15 m to 3.0 m. Mineralized zones are characterized by the presence of disseminated pyrite, pyrrhotite and arsenopyrite.
Mineralization has been intersected over a length of 250 m and has been tested to 150 m below surface. True widths of the mineralized zones vary from 2 m to 15 m with a cumulative width of the sub-parallel, folded mineralized zones of 30 m to 85 m. The mineralized zones strike 325° and dip steeply to the northeast. The mineralization is open to depth and along strike to the north but appears to peter out southward.
27 Deposit
Although 27 deposit is near the volcanic-sedimentary contact, like 24 deposit it has a different style of mineralization. The mineralization consists of free gold in narrow (average 7.5 mm) quartz veins. The wallrock throughout the zone contains 3% very finely disseminated pyrrhotite, locally concentrated in short, altered sections.
Seven mineralized zones were defined at the 27 deposit with true widths varying from 1 m to 10 m. The cumulative width of the subparallel mineralized zones reaches locally 120 m. Mineralization has been intersected over a length of 200 m and has been tested to 150 m below surface. The mineralized zones strike from 170° to 190° and dip steeply to the southwest to the northwest. The mineralization is open to depth.
Kim Deposit
The bulk of the mineralization of the Kim deposit is hosted by the mafic volcanic rocks, but a few gold showings are also present in the sedimentary sequence (Morgan, 1991). The gold mineralization at the Kim Zone is hosted by the more competent massive mafic flows.The mineralization was interpreted to have been formed as extensional veins in a reverse-dextral deformation corridor centered on the volcaniclastic rock horizon (Gaboury, 2021).
Mineralization has been intersected over a length of 1,000 m and has been tested to 350 m below surface. True width of the mineralized zone varies from 3 m to 30 m. The mineralized zone strikes 190° and dips steeply to the west. The zone remains open at depth and has a known extension to the south (Kim South).
Cass Deposit
The Cass deposit is hosted within and/or along the contacts of the Cass Gabbro and a volcaniclastic unit. The gold mineralization is associated with steeply-dipping quartz-carbonate-sulphide (predominantly arsenopyrite) veins with grunerite-garnet alteration selvages that can be subdivided into two mutually cross-cutting sets suggesting that both sets formed synchronously (Morgan, 1991; Gaboury, 2021).
The mineralization is intersected as seven stratigraphy-parallel and en-echelon like zones in gabbro with a cumulative strike length of 1,000 m. The mineralized zones vary mostly between 2 and 20 m in thickness. The mineralized zones strike 230° and dip steeply to the north-west. The mineralization is open to depth and along strike to the south but appears to peter out northward.
Treasure Island Deposit
The Treasure Island deposit is underlain by a succession of pillowed and massive mafic flows that are overlain by an intercalated intermediate to felsic volcanic horizon and argillite- to wacke-dominated turbiditic sedimentary rocks belonging to the Chalco Lake Group. The mineralization occurs as quartz-sulphide (pyrrhotite-pyrite±chalcopyrite) veins, as well as disseminated and stringer style pyrite and pyrrhotite.
Damoti Deposit
The iron formations are highly folded along N- to NE-trending axes, with the main mineralized zone being a U-shaped syncline fold named the Horseshoe Zone. The bulk of the mineralization is contained in a low grade envelop continuous over a straight length, which contains higher grade mineralized zone having an average dimension of 20 m long, 5 m wide and a vertical depth of 270 m.