Summary:
Deposit Type
Wasamac Deposit
The Wasamac deposit is an example of an Archean greenstone belt gold deposit hosted by the Francoeur-Wasa shear zone, a second-order brittle-ductile shear zone of the Cadillac–Larder Lake fault zone. Gold mineralization is constrained to the altered and sheared part of the Francoeur-Wasa shear zone. Regionally, the Wasamac deposit lies at the boundary between the orogenic gold district of Noranda and the dominantly intrusion-related gold systems of Kirkland Lake. The Wasamac deposit shares similar characteristics of both alkaline syenite intrusion-related gold deposits and orogenic gold deposits.
There are several examples of orogenic or intrusion-related deposits along the Cadillac–Larder Lake fault zone including: the Francoeur deposit (500 koz produced), Kirkland Lake deposits (21 Moz produced), Kerr-Addison (9.5 Moz produced), and Lapa (700 koz mineral resource) (Mériaud, 2015). One difference between Wasamac and these other deposits is that they all have mineralization related to veining, a characteristic that is missing at Wasamac, which exhibits disseminated mineralization only.
Francoeur and Arntfield Deposits
The Blake River Group rocks underlying the Francoeur and Arntfield gold deposits are intruded by diorite and gabbro masses. The Francoeur No. 3 deposit is the largest of a series of deposits located within the Francoeur-Wasa shear zone over a distance of more than 10 km. These deposits are, from west to east, the Cutting zone and the No. 1, 2 and 3 deposits of the Francoeur and Arntfield mine, the Wasamac Principal, No. 1 and 2 deposits as well as the Wingate deposit.
Mineralization at the Francoeur deposit is a gold replacement type with close coexistence of gold and pyrite disseminated within and peripheral to altered shear zones. Hydrothermal alteration is well developed, and alteration minerals have distinct zonation from orebody outward: albite-pyrite to carbonate-hematite to muscovite-chlorite. Gold mineralization is closely associated with these alterations, especially albite-pyrite alteration.
Mineralization
The Wasamac property is underlain by the Blake River Group within the Rouyn-Noranda mining district in the southern Abitibi Greenstone Belt (Abitibi greenstone belt) of the Superior Province of the Canadian Shield. The southern boundary of the Abitibi greenstone belt is along the Cadillac–Larder Lake Fault Zone, a major structural break marking the contact with younger metasedimentary rocks of the Pontiac Subprovince.
The Wasamac, Consolidated Francoeur, and Western Buff blocks are along the Francoeur-Wasa Shear Zone, a secondorder fault that is parallel and 2.5 km north of the Cadillac–Larder Lake fault zone; whereas the R.M. Nickel area is 1.6 km north of the Francoeur-Wasa shear zone. In the Wasamac deposit, the Francoeur-Wasa shear zone crosscuts the metavolcanic units of the Blake River Group. Along this break, the units of the Blake River Group have been tilted toward the North and follow the same east-west trend. The Francoeur-Wasa shear zone shows strong structural similarities with the Cadillac–Larder Lake fault zone, presenting a thick intense ductile shearing of the volcanic units, associated with strong metasomatic alteration.
Gold mineralization at Wasamac is typically associated with finely disseminated pyrite and stockwork of pyrite-rich microveinlets hosted in albite-sericite-ankerite alteration zones confined within the shear zone. The albite-sericite-ankerite alteration related to gold mineralization is typically beige-brown and visually distinguishable from the surrounding sheared rocks. Quartz veins are not common and do not significantly contribute to the gold endowment of the system.
The defined Wasamac deposit is continuous over 900 metres vertically and 2.7 kilometres along strike and remains open at depth and on its lateral extensions. The deposit contains five mineralized areas, from west to east: Main Area, Area 1-2, Area 3-4, Wildcat Zone, and MacWin Zone. Areas 1-2, 3-4, MacWin Zone, and most of the Main Area are contained within the Francoeur-Wasa shear zone. The Wildcat Zone occurs within a different structure.
The Main Area is located on the western part of the deposit where it is constrained to the west by the Horne Creek Fault. The upper part of the Main Area was mined during historic underground operations between 1965 and 1971. Gold mineralization in the Main Area occurs within several discrete sub-parallel zones that are generally 5 to 15 m (locally up to 25 m) true thickness. They include the Main Zone, Main Zone 2, Main Zone 3, Stockwork Zone, Footwall Zone, and Footwall Zone 2. The Main Zone, Main Zone 2, Main Zone 3 are confined to the Francoeur-Wasa shear zone and are associated with disseminated pyrite and stockwork of pyrite-rich micro-veinlets hosted in albite-sericite-ankerite alteration zones.
The Stockwork Zone, Footwall Zone, and Footwall Zone 2 occur below the Francoeur-Wasa shear zone and are primarily associated with relatively undeformed pyrite stockwork with minor albite alteration. They are locally associated with higher gold grades.
Areas 1-2 and 3-4 both contain one single mineralized zone characterized by albite-sericite-ankerite-pyrite alteration. It consists of a continuous structure interpreted as the eastern extension of the Main Zone. Area 3-4 is slightly offset relative to Area 1-2, which is interpreted to be related to a crosscutting structure that offset the shear zone and stratigraphy. Historically, the zone in Area 1-2 and Area 3-4 was separated into four zones (Zone 1, Zone 2, Zone 3, and Zone 4).
A small portion of Area 1-2 was mined during the last phase of production; however, only limited tonnage was extracted (approximately 100,000 tonnes of ore was mined). Area 3-4 was first intersected during the 2002-2004 drilling programs and was better defined during the 2011 drilling.
The MacWin Zone, formerly known as the Wingate Zone, was discovered in 1945 along the Francoeur-Wasa shear zone approximately 300 m east of Zone 3. Gold mineralization occurs both within the shear zone and in the hanging wall rhyolite. A small shaft was completed on the zone; however, this area was included in the mineral resources, but voluntary excluded from the mineral reserves defined in the present report.