The Spectrum-Red Dog property is located just southeast of Edziza Peak and 4 kilometres southwest of Nuttlude Lake.
Recent mapping (2015) on the Spectrum claims block defined a 1000- to 1500-metre-thick Triassic volcanic sequence (Stuhini Group) which varies from mafic volcanic and sedimentary strata at its base, through a middle sequence of intermediate tuffaceous volcanics and culminating in a calcareous sedimentary sequence with minor limestone at the top. Recognized in diamond drill core, syn-volcanic feldspar-porphyritic intrusions occur as dikes and sills within the volcanic stratigraphy and may represent the feeder system for the Stuhini volcanics.
Stuhini Group volcanics are unconformably overlain to the west and north by comparatively flat-lying Miocene and younger volcanic rocks of the Mount Edziza Volcanic Complex. Lower Jurassic Hazelton Group strata have not been identified in the area. However, Stuhini Group volcanics are known to be intruded by north-trending, Late Triassic to Early Jurassic dike-like bodies emplaced along zones of structural weakness. Three intrusive phases have been mapped: monzonite; diorite; and granodiorite, the oldest of which is thought to be a monzonite dike intersected by drilling in the Central Zone. There are currently no age dates for any of the intrusive suites described above, but they are interpreted to be coeval with those identified in the area of the Donnelly deposit (104G 086) to the southeast.
Four types of mineralization occur in the Spectrum-Red Dog area: 1) Pyrite with minor pyrrhotite occurs as disseminations and fracture-fillings in Upper Triassic cherts, tuffs and flows. This mineralization is largely syngenetic with the volcanic assemblage. Estimates of pyrite content range from 2 to 10 per cent. 2) Pyrite, arsenopyrite, sphalerite and galena occur in narrow quartz-carbonate veins within the Upper Triassic sediments and volcanics. These veins range from less than one 1 centimetre to 30 centimetres in width and contain high gold and silver values, particularly where arsenopyrite and/or sphalerite occur. A one metre sample across several veinlets assayed 1.2 per cent zinc, 4.11 grams per tonne gold and 10.97 grams per tonne silver. 3) Pyrite, pyrrhotite, chalcopyrite and magnetite occur in irregular, metasomatic replacement masses in limy sediments. This showing is located a few hundred metres south of the main occurrence. A grab sample of syenite and skarn contained 0.5 per cent copper, 4.94 grams per tonne gold and 0.68 grams per tonne silver. 4) Pyrite and chalcopyrite occur as disseminations and fracture-fillings in a north-northeast striking granodiorite dike (later called a monzonite dike) and adjacent wallrock that consists of Upper Triassic sediments and volcanics. The dike varies from 50 to 100 metres in width and has been traced along strike for 1200 metres. It dips from 60 to 80 degrees to the west. This porphyry-type mineralization is associated with sericite and secondary biotite alteration. A 15-metre section of drill core assayed 0.30 per cent copper. Samples of cherty tuff and pyroclastic wallrocks assayed up to 2.5 grams per tonne gold while the dike rocks assayed up to 0.60 grams per tonne gold.
The porphyry-style copper-gold mineralization occurs within a north-south trending, moderately west dipping and fault-bounded structural panel of Triassic Stuhini volcaniclastic lithologies intruded by syn- to late-mineral monzonite dikes. As of 2016, porphyry-style mineralization had been defined over a strike length of 1000 metres, with widths of 70 metres to 200 metres. It has been tested to 400 metres downdip and it remains open along strike and downdip. It was intruded by a late, predominantly barren monzonite intrusion at depth climbing north towards surface where it over-prints porphyry copper-gold mineralization.
Mineralization occurs as quartz-pyrite-chalcopyrite with or without magnetite veinlets, stockworks, fracture fills and fine-grained disseminations of pyrite and chalcopyrite. Metal grades appear to be directly related to the abundance of quartz-sulphide-magnetite vein development.
Most monzonite dikes intersected in drilling are weakly mineralized, mainly with disseminated pyrite and chalcopyrite and with lesser quartz-pyrite-chalcopyrite with or without magnetite veining. They are interpreted to indicate intrusion during the waning stages of the porphyry copper-gold mineralizing phase. Rarely have syn-mineralizing monzonite dikes been intersected that show similar degrees of quartz-pyrite-chalcopyrite-magnetite vein development, as found in the surrounding volcanic host rock. Spatially, the well mineralized syn-mineralization monzonite dikes have been intersected more frequently towards the northern third of the deposit, thereby interpreted to suggest a possible zonation. Rare molybdenite has been intersected to date; bornite is not present.
Potassic alteration related to porphyry Cu-Au mineralization forms narrow, diffuse bands of K-feldspar with or without disseminated epidote within siltstone units. This alteration is cut by quartz-sulphide-magnetite veining with K-feldspar halos, selective replacement of mafic sites by biotite in some intrusive phases and more pervasive disseminated magnetite. The high temperature quartz-sulphide-magnetite veins zone laterally outwards to quartz-chlorite-chalcopyrite veins. A large proportion of the Stuhini Group volcaniclastics with porphyry Cu-Au mineralization is associated with strong pervasive chlorite-epidote-magnetite alteration, which is interpreted as alteration of earlier biotite hornfels. This alteration may zone outwards to areas of weaker diffuse and selective chlorite-epidote-magnetite (with or without carbonate) replacement. In the Skarn and South Copper zones a calc-silicate alteration has been mapped that may include epidote, diopside, tremolite/actinolite, chlorite and magnetite as weak replacements of calcareous volcanic wackes and mafic tuffs. The calc-silicate alteration is gradational with chlorite-epidote-magnetite alteration. Quartz-sericite-pyrite alteration, which overprints the earlier alteration assemblages, can be expressed either as wide pervasive zones, such as in the hangingwall of a prominent northwest-trending structure crossing the Central Zone, as metre- to tens of metres-scale patchy and pervasive alteration or as finer, centimetre-scale haloes on quartz-pyrite veining.
Columbia Gold Mines described several new zones after their 1991 work (Assessment Report 20860). The East QC, West QC and Porphyry Gold Zones contain visible gold, pyrite, arsenopyrite and minor base metals within potassic to propylitic altered andesitic tuffs. Several other zones of mineralization indicated on company maps include the Fog, Skarn, 500 Colour and Boundary zones and the 4400 vein.
The 500 Colour zone consists of a stockwork of quartz veins and veinlets which contain sphalerite, galena and chalcopyrite. Fine arsenopyrite was found in thin seams adjacent to veins in one drill hole. The mineralization is spatially related to the margins of the westerly dipping monzonite (granodiorite?) dike. The East QC zone was outlined along a 550 metre length and to a depth of 90 metres. To 1991, the zone remained open along strike and to depth. The West QC zone trends northwesterly and dips steeply to the west having a strike length of 760 metres. The Porphyry zone was drilled along a 300 metres strike length to a depth of 60 metres. This zone is reported to be 30 metres west of the QC mineralization and is found within a broad zone of gold-copper mineralization.
Indicated reserves in 1983 at Red Dog were 2,177,040 tonnes grading 1.26 grams per tonne gold (Northair Mines Ltd. Annual Report 1983). In 1991, Columbia Gold Mines calculated a "drill indicated geological reserve" within the tested portion of the Porphyry, QC and 500 Colour Zones of 614,700 tonnes grading 12.3 grams per tonne gold using 5 grams per tonne gold as a cut-off (Assessment Report 22838). In the same year, Orcan Mineral Associates calculated "drill indicated reserves". One reserve was based on a 10 grams per tonne gold cut-off of 274,900 tonnes at an average grade of 15.77 grams per tonne gold and the second based on 5 grams per tonne gold cut-off of 504,800 tonnes grading 9.6 gram per tonne gold (Assessment Report 22838, page 8).
Skeena’s current Central Zone geological model includes the 500 Colour, 33, Skarn and Porphyry zones, which were previously considered to be separate mineralized occurrences. The 300 Colour and East Creek zones remain separate from the Central Zone.
See Work History year 2017 below for more recent resource update.
The property was originally staked as the Spectrum claims by Spartan Exploration Ltd. in 1969 to cover a copper occurrence there. Mitsui Mining and Smelting operated the property in 1970 followed by Imperial Oil Enterprises in the next 3 years. This work included geochemical and geophysical surveys culminating in 1973 in 4 diamond drill holes totalling 450 metres. The property was restaked as the Red Dog claims in 1975 and optioned to Consolidated Silver Ridge Mines Ltd. by owner Placer Development Ltd. This optionee worked the property by conducting more geochemical surveys in 1978 and trenching and 10 diamond drill holes totalling 828 metres in 1979. In 1980, Consolidated Silver, now the owner, drilled a further 18 holes totalling 2336 metres. Northcal Resources Ltd. (formerly Consolidated Silver Ridge) conducted an unspecified amount of work in 1981 and 1982, including more trenching (see the related GR occurrence - 104G 122).
Cominco Ltd. optioned the property from Northcal and Newhawk's Hawk claims to the north of the Red Dog claims, and in 1984 completed a surface sampling program and a geophysical (very low frequency magnetic, (VLF-Mag) surveys over the Central zone. Between 1987 and 1989, under an option agreement with Cominco, Moongold Resources Ltd. who completed rock and soil sampling, as well as VLF-mag and resistivity surveys over the Hawk vein. Moongold did not, however, pursue its option further. In 1989, Cominco completed a ten hole, 1,199. metre diamond drilling program. The option lapsed the following year.
In 1990 and 1991, Columbia Gold Mines, holding both the Red Dog and Hawk claims, under option from Cominco, drilled 3142 metres in 26 holes and excavated 631 metres of trenches. It was in consequence of the 1990 drilling program that the main mineralized zones found on the Spectrum claims block were first identified as distinct mineralized occurrences. In 1991, results were consolidated with the results of previous surface drilling programs and an initial Mineral Resource estimate for Central Zone was compiled. See Inventory section for this data. In 1992 Columbia added the six hole, 710.33 metres, to the body of previous drilling results. At the same time, Columbia carried out a limited prospecting program to identify northerly extensions of what was now called the Central zone.
In early 2005, a report on resource, geology and petrography was submitted for assessment on the Spectrum property for operator Trans Pacific Mining Ltd and owner Seeker Resources Corp. The results of the resource model are summarized in a report by Mining Associates of Australia dated May 12,2004 which is attached to Assessment Report 27688. The report puts the Spectrum Project resources into JORC format and based on a cut-off grade of 5 grams per tonne gold, a resource of 474,615 tonnes at 11.4 grams per tonne gold is estimated for a total contained metal content of 173,555 ounces of gold. By reducing the cut-off grade to 2 grams per tonne a contained metal content of 255,659 ounces of gold at 6.05 grams per tonne gold is derived.
In 2005, a visit was made to the Spectrum property to assess the possibility of mobilizing a small diamond drill rig. Three water samples and some minor geological work was done. Seeker Resources Corp is indicated as owner and Cambria Ice Field Resources Inc as operator.
Columbia’s 1992 work program marked the end of exploration activity on the Spectrum claims block, at least until 2014 when the Skeena Resources gained a 100 interest in the property. Efforts were instead focused on lobbying the B.C. government to amend the Mount Edziza Provincial Park boundary, thereby to allow access and further mineral exploration work on the Spectrum property.
Lobbying was first done by Arkaroola Resources Ltd., which purchased the property from Columbia in 1996, and then by Seeker Resources Corp. (“Seeker”) when it took up ownership in 2002. During this process it was reported that Seeker’s Spectrum property was maintained in good standing by cash payments in lieu of exploration work. Lobbying was ultimately successful, and a Designated Access Corridor was established. Up to 2011 Seeker also carried out baseline environmental studies, applied for drilling and archaeological permits (in 2009), posted a cash bond with the B.C. government and optioned its Spectrum property holdings to Transpacific Mining Ltd. TPM re-estimated the Mineral Resources for Central Zone and undertook a petrographic study, but did not pursue its option further.
Eilat Exploration Ltd. took over the block of ten Spectrum mineral claims 2011, with a 10 per cent stake held by Keewatin Consultants (2002) Ltd. An airborne magnetic survey was completed in 2012 (flown by Fugro Airborne Surveys). On April 14, 2014, the Company entered into a Conditional Asset Purchase Agreement (CAPA) with Eilat and Keewatin with respect to the acquisition of a 100 per cent interest in the Spectrum claims block.
Skeena Resources Ltd was granted 100 per cent ownership on October 27, 2014 following completion of the terms of CAPA, which required Skeena to issue an aggregate of 80 million common shares of the Company at a deemed issue price of six cents Canadian per common share. Sixty-four million of these shares were issued to Eilat, with the balance (16 million shares) issued to Keewatin.
On the Spectrum claims block and from September 2014 to the close of the last field season in October 2016, Skeena has completed: an airborne LiDAR (Light Detection and Ranging), topographic survey and lineament analysis; geological mapping; prospecting; soil and rock geochemical sampling; an IP geophysical survey; and a ground magnetics geophysical survey.
A new 2017 mineral resources estimate for Spectrum (Central zone) is based on 164 diamond drill holes of which 88 were completed by Skeena totalling 34,598 metres and 22,581 assay intervals. Resource estimates for the Spectrum Central zone (at 0.4 grams per tonne gold equivalent cut-off) are as follows. In the Indicated resource category there are 31.2 million tonnes grading 0.94 gram per tonne gold, 2.6 grams per tonne silver and 0.10 per cent copper; and in the Inferred category there are 29.8 million tonnes grading, 0.47 gram per tonne gold, 1.4 grams per tonne silver and 0.12 per cent copper (Skeena Resources Ltd, Press Release April 20, 2017).
See Hawk - 104G 005 for further information.