The Wasamac property is located approximately 15 km west-southwest of Rouyn-Noranda, Quebec, Canada, within the central portion of the Abitibi gold mining district. Rouyn-Noranda is serviced by daily flights to Montreal. The Property is accessed from Provincial Highway 117 that links Rouyn-Noranda and the community of Arntfield. A secondary road (Rang des Cavaliers) leads directly to the property from Provincial Highway 117.
History
The Wasamac property has been the object of extensive exploration work. Gold mineralization was originally discovered in 1936 by Mine d’Or Champlain through surface trenching work. Subsequent surface diamond drilling intersected encouraging gold values, however, geological continuity initially appeared erratic. A 60 m shaft (Wildcat shaft) was sunk and one underground level was developed.
In 1944, Mine d’Or Champlain changed its name to Wasa Lake Gold Mines and initiated an exploration program. This led to the discovery of a new gold bearing zone, the Main Zone, located approximately 300 m north of the Wildcat Zone.
During the period from 1945 to 1948, an inclined shaft was sunk at a 55° angle down to the 1,000 ft level which was followed by significant development work on five underground levels. “Ore reserves” established at the time were approximately two million tonnes at an average grade of 5.28 g/t Au. This estimate is considered to be historical in nature and should not be relied upon, however, it does give an indication of mineralization on the property.
In 1960, Barnat Mines Ltd., in association with Little Long Lac Gold Mines, acquired control of Wasa Lake Gold Mines and changed its name to Wasamac Mines Ltd. A production decision was reached in 1964, the underground workings were dewatered and rehabilitated, and commercial production officially commenced on April 1, 1965.
From 1965 to 1971, approximately 1.9 million tonnes of ore from the Wasamac deposit were treated by Wasamac Mines Ltd. and later by Wright-Hargreaves Mines Ltd. An average recovered grade of 4.16 g/t Au was recorded (Karpoff, 1986)
In May 1971, operations ceased due to low gold prices (approximately US$35/oz), increasing production costs, and the abolishment of Federal aid to the mining sector. Consequently, very little exploration was conducted until 1974, when Lac Minerals Ltd. (Lac Minerals) carried out limited diamond drilling on the MacWin Zone and deep diamond drilling work on the Main Zone.
During the early 1980s, Lac Minerals re-activated exploration work on the property and in 1980 completed 80 km of horizontal loop electromagnetic (HLEM), magnetometer, and very low frequency (VLF) ground geophysical surveys. This work was followed up with surface geological mapping, and in 1981 the company drilled 64 surface holes totalling 7,375 m in an attempt to: Verify the down dip extension of the Main Zone.
1. Verify the down dip extension of the Main Zone.
2. Evaluate the surface pillar zone through definition drilling at 30 m spacing.
3. Evaluate the down plunge extensions of the MacWin, Wildcat, and N 2 zones.
In 1983, following pre-feasibility work on the surface pillar recovery, Lac Minerals drilled an additional 1,880 m in 33 surface holes at a 15 m spacing, to upgrade the level of confidence of this surface zone.
Several studies considering a potential open-pit operation were prepared for the surface pillar, however, low gold prices at the time prevented the company commencing production.
Following the option agreement with Lac Minerals in 1986, the exploration work conducted by Ressources Minières Rouyn (RMR), which changed its name to Richmont in 1991, consisted of 11 surface holes totalling 3,710 m, and was aimed at further evaluating the surface pillar zone along with the Zone 1 and Main Zone down dip extensions.
From November 1987 to June 1988, RMR dewatered the mine to a depth of 975 ft and rehabilitated the 400 ft and 800 ft levels in an attempt to explore the down dip extension of Zone 1 through underground drilling. Again, the Project was not developed due to low gold prices.
In 1994, Richmont reclaimed the Wasamac Mine site. All surface installations were dismantled, the shaft was capped, and the tailings pond was re-vegetated.
From 1989 to 2002, exploration work included eight surface holes totalling just over 4,500 m primarily targeting the WSZ at depth (Zones 1 and 2).
In 2002, Richmont re-activated exploration work in an attempt to evaluate the down plunge extension of Zones 1 and 2 at depth. Richmont drilled a 420 m hole from surface that targeted the down plunge extension of Zone 2. Drill hole WS-02-01 intersected 4.15 g/t Au over a true width of 6.8 m. Richmont followed up with a 15-hole (9,475 m) surface drilling program in 2003. All holes intersected the WSZ at depth which demonstrated good continuity. Nine holes returned assay values greater than 4.0 g/t Au and six holes returned grades greater than 4.5 g/t Au in Zones 2 and 3. An additional 3,859 m of drilling was completed in 2004. Results from the 2002 to 2004 drilling supported an internal Inferred Mineral Resource estimate for Zones 2 and 3 (Guay, 2004) as discussed under Historical Mineral Resource Estimates.
In 2005, one hole (WS-05-21), 745 m in length, was drilled west of Zone 1, and intersected gold values of 0.91 g/t Au over 4.1 m. In 2007, two holes were completed on the West extension of the Wildcat Zone. Hole WS-07-22 cut the Wildcat structure with a gold intercept of 1.39 g/t Au over 6.6 m. In 2008-2009, three exploration holes targeted geophysical anomalies that could indicate parallel structure to the WSZ. Alteration zones were intersected but returned no significant gold values.
From May 2011 to July 2012, Richmont completed significant exploration drilling targeting the Main Zone and Zones 1, 2 and 3 (further described in Chapter 10). In 2011, a total of 78 holes were completed (11 holes were stopped and re-drilled due to excessive deviations), totalling approximately 52 km. In 2012, an additional 87 NQ diameter drill holes were completed, totalling approximately 44 km.
In 2012 Richmont also conducted a 16-hole drill program totalling 11,803 m to test the WSZ between the vertical depths of 200 m and 1,000 m across claims optioned from Globex Mining Enterprises Inc. (Globex). All holes intersected the WSZ, however, where intersected, the structure appeared to be less highly deformed and not as highly altered as elsewhere. The best intersections from within the WSZ included 4.07 g/t Au across 5.60 m in hole WG-480-02, 2.25 g/t Au across 6.70 m in hole WG-480-04, 1.07 g/t Au across 8.00 m in hole WG-482-o2, and 1.43 g/t Au across 5.00 m in hole WG-589-01. Several short intersections were achieved outside of the WSZ.
From December 2015 to January 2016, Richmont completed two drill holes totalling 600 m to test the eastern and western extensions of the Wildcat Zone. The best intersections included 2.55 g/t Au across 2.00 m in hole WC-15-01 east of the zone and 1.78 g/t Au across 2.00 m, 2.71 g/t Au across 3.50 m, 1.53 g/t Au across 4.5 m and 14.02 g/t Au across 1.50 m in hole WC-16-01, west of the zone.
Regional geology
The Wasamac property is located within the Rouyn-Noranda mining district, in the Abitibi greenstone belt of the Superior province of the Canadian Shield. The area consists mostly of felsic to mafic volcanic rocks of Archean age together with related dioritic sills which are concordant to the regional rock formations. These volcanic and intrusive rocks have generally been metamorphosed to the greenschist facies.
The Superior Province is the largest exposed Archean craton in the world and hosts several world class gold deposits. It has yielded nearly 300 million ounces of gold from hundreds of deposits since the beginning of the twentieth century. One prominent characteristic of all significant gold deposits in the Superior Province is their occurrence within or immediately adjacent to greenstone belts. Another characteristic is their occurrence within major tectonic zones which comprise a series of shear zones (Colvine et al., 1988). The Superior Province is divided into four major subprovince types (Card and Ciesielski, 1986): volcano-plutonic, plutonic, metasedimentary, and high metamorphic grade gneiss. The boundaries of these subprovinces are either major dextral, transcurrent, east-striking faults, or zones of structural and metamorphic transition.
The greenstone belts which host the gold deposits occur as east-north-easterly trending ribbon domains in the volcano-plutonic terrains. They typically consist of mafic to ultramafic and felsic metavolcanic rocks, interlayered with metasedimentary rocks. The supracrustal rocks were intruded by syn-volcanic plutons. Saturated and under saturated felsic to mafic igneous rocks intruded into the greenstone belts in late Archean.
The metamorphic grade of most of the present greenstone terrains ranges from sub-greenschist to greenschist facies in the centre, to lower amphibolite facies at the margin. Amphibolite facies contact metamorphic aureoles occur around intrusions into the greenstones (Jolly 1978, 1980) with the exception of the synvolcanic ones.
Local Geology
Volcanic rocks of the Blake River Group, which host the gold deposits, are the principal Archean rock types exposed in the study area. Rocks of the Blake River Group are bounded to the north by the Porcupine-Destor-Parfouru fault system, and to the south by the Larder Lake-Cadillac Fault. The Blake River Group is the youngest volcanic sequence in the Superior Province and forms a central volcanic complex, which is characterized by cyclic bimodal andesite-rhyolite units of calc-alkaline and tholeiitic affinity (Péloquin et al. 1990). These units are underlain by the sedimentary rocks of the Timiskaming Group, which are overlain by mildly deformed Proterozoic sedimentary rocks of the Cobalt Group along the south boundary. The volcanic rocks are intruded by two major intrusive rocks, mafic gabbro-diorite sills and stocks that are either synvolcanic or clearly post-tectonic. All lithologies, except for the syenites, are folded and metamorphosed.
Two large granitic bodies are located just north of the Wasamac property; the Flavrian and the Powell batholiths. These two bodies cross-cut the volcanic rocks and are located within the general axis of the Blake River Group syncline. Elsewhere on the property, diabase dykes of Proterozoic age and lamprophyre dykes are also found.
The property can basically be subdivided into two distinct volcanic sequences; the southeastern portion is characterized by massive mafic to intermediate flows, while the northern portion is underlain by an intercalation of mafic volcanic flows, felsic tuffs, and brecciated rhyolite. These two volcanic sequences are separated by a subsidiary fault of the Larder Lake-Cadillac tectonic zone, called the WSZ, which crosses the entire length of the property from east to west.
Elsewhere on the property, several small mafic intrusive bodies composed of gabbro and diorite can be found. These intrusive bodies vary in size and seem to be generally concordant with the regional stratigraphy which runs east-west.
Below the Proterozoic Cobalt sediments, just south of the Wasamac property, the Larder LakeCadillac Fault cuts the Archean rocks. This regional fault separates the rocks of the Blake River Group to the north with the sedimentary rocks of the Timiskaming Group to the south. Beside this major structure, the Archean rocks are also affected by two families of very different faults, one of which is related to the WSZ, and the other to the Horne Creek fault. Like the regional structures, these faults and shear zones are striking east-west. The WSZ is a reverse fault with a north dipping trend and is strongly hydrothermally altered on the Wasamac property. Most of the gold mineralization found on the property to date is related to the WSZ.
Minor folding has been observed on the property. Schistosity varies between southeast to northeast with a northern dip of approximately 55° and corresponds to regional schistosity. The stratigraphic top, from pillow observations, is towards the north.
Mineralization
The WSZ bisects the property with an azimuth of 265°, a dip to the north of 50° to 60°, and a maximum thickness of 80 m. It is characterized by the development of a strong mylonitic fabric and an intense hydrothermal alteration that destroyed the primary structures and textures of the protolith. Mineral assemblages of rocks within the shear zone consist of chlorite, carbonate, hematite, albite, and sericite in the middle of the zone. Gold is associated with a dissemination of fine pyrite in the altered portions of the shear zone.
During the production era, two gold bearing zones were mined, namely the Main Zone and the East N°1 Zone (now Zone 1). Some limited tonnage was also extracted from the Wildcat Zone.
Main zone.
Originally discovered in 1944 through surface drilling, the Main Zone is described as a well laminated mineralized zone. It is located near the centre of the property, within the WSZ and highgrade areas display true widths of 10 m to 15 m (up to 25 m locally) over a strike length of 400 m. Gold mineralization is associated with quartz, carbonate, sericite, albite, pyrite, and chlorite inside the shear zone. Visible gold is rare, and high-grade gold assays are generally associated with high silica content and fine-grained pyrite (Gill, 1947). If the entire mineralized zone is considered, including lower grade parts, the width of the mineralized zone can be up to 50 m.
Relationship between main lithologies: The Wasa shear zone and mineralized zones at 500 m below surface
Main Zone geological section
Zone 1
Located approximately 400 m east of the Main Zone, Zone 1 has a similar mineralogical assemblage to the Main Zone. The high-grade segments have true widths of 4.5 m to 7.5 m over a strike length of 150 m. During the last phase of production, underground development work was undertaken in an effort to mine this gold bearing lens, however, only limited tonnage was extracted in the upper part of the zone (approximately 100,000 t of ore was mined). The thickness of the mineralized envelope can be up to 20 m.
Zone 1 geological section
Zone 2
In September 1944, surface drilling intersected Zone 2 located in the upper part of the shear zone, near the hanging wall, approximately 800 m east of the Main Zone. Higher grade portions have average thicknesses of three to six metres over a strike length of 225 m. This zone was partially developed from underground, but no production was recorded.
Zone 2 geological section
Zone 3
Zone 3 was first intersected during the 2002-2004 drilling programs and further defined during the 2011 drilling. The mineralization is located in the lower part of the shear zone, near the footwall, below the MacWin Zone. Hematized, red-coloured felsic dykes appear to be associated with the mineralized zones. These are difficult to recognize due to shearing, alteration, and mineralization.
The dykes are likely related to the shear zone deformation and have an echelon geometry within the shear zone. Since they appear to be more competent compared to the surrounding andesites, the dykes have been affected by more brittle deformation. This brittle deformation may have created the fractures which could have served as conduits to the mineralized fluids. RPA recommends additional geological studies to better understand the exact relation between the dykes and the formation of the mineralization.
MacWin Zone
Formerly known as the Wingate Zone, the MacWin Zone was discovered in 1945 within the WSZ near the eastern property boundary. Gold mineralization is located outside the shear zone, within rhyolites located just at the hanging wall of the shear.
Wildcat Zone
The Wildcat Zone was discovered in 1936, the first gold showing discovered on the property. Located 300 m south of the Main Zone, the mineralization is related to a carbonate altered zone at the margins of a gabbroic unit. This zone, which has been interpreted as being erratic, was investigated through underground development work in 1937, however, operations ceased a year later due to lower than expected gold grades. Further surface drilling was subsequently completed in 1944, but efforts failed to improve the grade. Limited tonnage was extracted from this zone. The Wildcat shaft was later used as a ventilation raise, and was connected to the Wasamac Mine by a drift on the 200 ft level. In 1981, Exploration Long Lac completed 18 holes for 1,562 m. These vertical holes showed a possible extension of the mineralization to the southeast (Caillé, 1981). Richmont drilling in this area also indicated a possible extension of the mineralized structure to the southwest.
DEPOSIT TYPES
The Wasamac deposit is an Archean greenstone-hosted gold deposit hosted in the WSZ, a second-order ductile shear zone of the Cadillac–Larder Lake Fault Zone. Gold mineralization is constrained to the altered and sheared portion of the WSZ. The following is taken from Dubé and Gosselin (2006).
Greenstone-hosted quartz carbonate vein deposits occur in deformed greenstone belts of all ages elsewhere in the world, especially those with variolitic tholeiitic basalts and ultramafic flows intruded by intermediate to felsic porphyry intrusions, and sometimes with swarms of albitite or lamprophyre dykes.
They are distributed along major compressional to transpressional crustal-scale fault zones in deformed greenstone terranes commonly marking the convergent margins between major lithological boundaries, such as volcano-plutonic and sedimentary domains. The large greenstone-hosted quartz-carbonate vein deposits are commonly spatially associated with fluvioalluvial conglomerate (e.g., Timiskaming-type) distributed along major crustal fault zones. This association suggests an empirical time and space relationship between large-scale deposits and regional unconformities.
These types of deposits are most abundant and significant, in terms of total gold content, in Archean terranes, however, a significant number of world-class deposits are also found in Proterozoic and Paleozoic terranes. In Canada, they represent the main source of gold and are mainly located in the Archean greenstone belts of the Superior and Slave provinces. They also occur in the Paleozoic greenstone terranes of the Appalachian orogen and in the oceanic terranes of the Cordillera.
The greenstone-hosted quartz-carbonate vein deposits correspond to structurally controlled, complex epigenetic deposits characterized by simple to complex networks of gold-bearing, laminated quartz-carbonate fault-fill veins. These veins are hosted by moderately to steeply dipping, compressional, brittle-ductile shear zones and faults with locally associated shallowdipping extensional veins and hydrothermal breccias. These deposits are hosted by greenschist to locally amphibolite-facies metamorphic rocks of dominantly mafic composition and formed at intermediate depth (5 km to 10 km). The mineralization is syn- to late-deformation and typically post-peak greenschist-facies or syn-peak amphibolite-facies metamorphism. It is typically associated with iron carbonate alteration. Gold is largely confined to the quartz-carbonate vein network but may also be present in significant amounts within iron-rich sulphidized wall rock selvages or within silicified and arsenopyrite-rich replacement zones.
There is a general consensus that the greenstone-hosted quartz-carbonate vein deposits are related to metamorphic fluids from accretionary processes and generated by prograde metamorphism and thermal re-equilibration of subducted volcano-sedimentary terranes. The deep-seated gold transporting metamorphic fluid has been channelled to higher crustal levels through major crustal faults or deformation zones. Along its pathway, the fluid has dissolved various components, notably gold, from volcano-sedimentary packages, including a potential gold-rich precursor. The fluid then precipitated as vein material or wall rock replacement in second and third order structures at higher crustal levels through fluid pressure cycling processes and temperature, pH and other physico-chemical variations.
A source: NI 43-101 – Technical Report Wasamac Project – Feasibility Study. BBA.