Summary:
The Meadowbank property comprises a number of Archean-age gold deposits hosted within polydeformed volcanic and sedimentary rocks of the Woodburn Lake Group, part of the Western Churchill supergroup in northern Canada.
Three mineable gold deposits, Goose, Portage and Vault (all now mined out), have been discovered along the 25-kilometre long Meadowbank gold trend, and the PDF deposit (a fourth deposit) has been outlined on the northeast gold trend. These known gold resources were within 225 metres of the surface, making the deposits amenable to open pit mining. In addition, two mineable deposits have been discovered at the Amaruq satellite deposit, the Whale Tail and V Zone, which come together at depth northeast of Whale Tail Lake. Both extend from surface, making them amenable to open pit mining. A ramp is being driven between the two deposits and is currently 350 metres below surface, in the footwall of Whale Tail deposit.
The area of the Meadowbank mine gold deposits is underlain by a complex, polydeformed package of intermediate volcaniclastic rocks and wackes with subordinate, interlayered iron formation, pelitic and ultramafic schists, and quartzite. The deposits are located within a structurally complex area in a narrow neck of supracrustal rocks, sandwiched between granite plutons. There are two main deposit types: iron-formation-hosted gold and lode gold (disseminated/replacement style). The iron-formation-hosted deposits are represented by the Portage and Goose deposits, while the disseminated/replacement lode gold deposits are best represented by the Vault deposit.
The main mineralized occurrences at Amaruq are hosted within a northeast-trending sequence of mafic and ultramafic sub-volcanic to volcanic rocks interlayered with various combinations of fine-grained clastic rocks, chert, graphitic iron-rich mudstone and iron formation. They correspond to mesothermal-type lode-gold mineralization, including (but not restricted to) hybrid, stratiform and vein-type iron-formation-hosted gold deposits.
Mineralization
The Amaruq satellite deposit at Meadowbank is located 50 kilometres northwest of the Meadowbank mine. The Whale Tail deposit is a folded deposit with a defined strike of 2.3 kilometres from surface to a depth of 1,075 metres locally. The V Zone is a series of parallel stacked quartz vein structures dipping shallowly (30 degrees) near surface and more steeply (60 degrees) at depth, extending to 800 metres locally. Both deposits are open along strike and at depth. Three contrasting styles of mineralization coexist on the Amaruq property. In all three styles, gold is found associated with pyrrhotite and/or arsenopyrite as 25 to 50 micron inclusions or grains along fractures, or simply as free grains in a quartz rich gangue.
The first mineralization style corresponds to occurrences of pyrrhotite-quartz-amphibole-carbonate as layers, lenses and/or disseminations, mostly restricted to the silicate-sulphide iron formations of Whale Tail’s north domain. The second mineralization style comprises silica flooding with significant pyrrhotite, arsenopyrite, and local pyrite stockwork and disseminations, within a gangue of amphibole-carbonate. The third mineralization style is between decimetres and several metres thick, quartz-sulphide-native gold veins cutting through the whole Kangislulik-Whale Tail-V Zone rock sequence. These veins are best developed in the mafic and ultramafic volcanics, where they are hosted in biotite-altered and moderately-to-strongly schistose zones. The overall sulphide content of these veins is generally low (1-5% maximum) and most commonly comprises arsenopyrite, galena, sphalerite, and/or chalcopyrite. These veins seem more abundant and best developed in the hinge zone of the regional fold and seem to be restricted to shallow southeast-dipping, high-strain corridors therein.