Summary:
The various mineralization styles present on the Marban property can be characterized as sub-types of the orogenic class of gold deposits, most commonly shear-zone hosted gold mineralization within greenstone terrains.
Greenstone-hosted quartz-carbonate vein deposits occur as quartz and quartz-carbonate veins, with valuable amounts of gold and silver in faults and shear zones located within deformed terrains of ancient to recent greenstone belts commonly metamorphosed at greenschist facies (Dubé and Gosselin, 2007). Greenstone-hosted quartz-carbonate vein deposits are a subtype of lode gold deposits (Poulsen et al., 2000). They are also known as mesothermal, orogenic. They consist of simple to complex networks of gold-bearing, laminated quartz-carbonate fault-fill veins in moderately to steeply dipping, compressional brittle-ductile shear zones and faults, with locally associated extensional veins and hydrothermal breccias.
The Marban property lies within the Archean Abitibi greenstone belt of the Superior Province, Quebec, which consists of alternating east-trending metavolcanic-plutonic and sedimentary belts that are bounded by crustal-scale faults. The Abitibi belt has been divided into a Northern Volcanic Zone (NVZ) and a Southern Volcanic Zone (SVZ) (Chown et al., 1992). The Marban property is located in the southern portion of the SVZ, where the Parfouru fault separate the Blake River segment to the west from Malartic segment to the east (Daigneault et al., 2002). The western portion of the property contains the eastern end of the Blake River Group, that appear as a north-dipping panel with faulted contacts bordered with the sedimentary units of the Kewagama to the north and Cadillac to the south (De Souza et al., 2020). To the east, the Malartic segment is subdivided into the Malartic Group, plume-derived komatiitic-tholeiitic marine-plain volcanic assemblages divided from north to south, into the La Motte-Vassan, Dubuisson, and Jacola formations and the Louvicourt Group representing an arc-type complex subdivided into the Val-d’Or Formation, a transitional to calcalkaline volcanic complex, and the Heva Formation, characterized by geochemically distinct iron tholeiites.
The metavolcanic rocks within the Marban property are cut by three major northwest- to west-northwest- striking shear zones of regional extent—the North, Norbenite, and Marbenite shears. The Marbenite shear hosts the Marban deposit, while the Norbenite shear hosts both the Kierens and Norlartic gold deposits and the North shear hosts the North zone.
The Marban deposit, one of numerous gold deposits on the greater Marban Property, is located at the Marbenite shear and extends in the hanging wall rocks for several hundreds of metres. It sits immediately to the east of a curvature in the Marbenite which is trending more east-west in this particular area. The southernmost part of the mineralisation is hosted by a strongly sheared komatiite unit within the Jacola Formation. Going north, the Mine Sequence corresponds to basaltic volcanics hosting most of the gold mineralization of the deposit. The mafic unit in the Marban deposit presents a significant thickening, compared to the correlated basalt horizon east and west, due to a multi-phased folding that shows a doubly plunging fold axis interference pattern which implies an early fold phase overprinted by subsequent east-west folding. The basaltic unit can be geochemically divided into two different basalts. A magnesium-rich basalt to the south that overlay a ferriferous basalt to the northern part of the Mine Sequence.
The Marban deposit is also characterized by minor cross-cutting shears that link early fold hinges together. The shears are plunging 40° to 70° to the north and often host gold zones. North of the basaltic units, the komatiite is injected by multiple felsic dykes, namely the Marban Dyke area. Those dykes are locally strongly altered and sheared, and contain gold mineralisation.
Gold mineralization at the Marban deposit occurs primarily within the Mine Sequence basalts mostly within the ferriferous basalt or at its folded contact with the magnesian basalt. The mineralization consists of quartz and quartz-carbonatechlorite veins and veinlets with disseminated pyrite and pyrrhotite mostly within the carbonatized, chloritized and albitized wall rock. Veins and veinlets vary in thickness from one centimetre to few metres, but they form stockworks that can be up to 70 m thick. Mineralization is also hosted within the north-dipping shear zones and associated felsic to intermediate sills and dykes.
The Kierens and Norlartic deposits are localized along the Norbenite shear, an important northwest trending deformation zone that dips moderately to steeply northeast. Komatiites, along with mafic and intermediate dykes, are included within the shear zone. Some late, weakly deformed felsic dykes locally cut the previous units. The gold mineralization is closely associated with carbonatized, albitized and pyritized intermediate intrusions that contain a stockwork of quartz-carbonate veinlets.
The North Zone gold mineralization are emplaced as sub-parallel zones dipping 60º to the northeast recognized within the north shear and are confined to zones of quartz-carbonate veining and pyrite alteration within sheared iron-rich tholeiitic basalt (Stuart and Martin, 1988). Intermediate dykes across the deposit seem to be spatially correlated with the different zones but the gold still mostly remains in the hosting mafic volcanic.
The North-North Zone is a near-surface intrusive-hosted deposit with mineralized quartz-tourmaline stockwork. Gold mineralization is confined to a conformable quartz-albite-carbonate-pyrite alteration envelope with quartz-tourmalinecarbonate vein stockwork localized in the central portions of a 60 m wide granodiorite sill. The sill was emplaced within a sequence of deformed ultramafic and mafic volcanic rocks. The sill and alteration envelope strike northwesterly and dip 40° to 55º to the northeast.