Summary:
Mineralisation is considered to be a mesothermal, vein and alteration style deposit similar to many other deposits in the Kalgoorlie district.
Regionally, Cannon is in the western part of the Bulong ultramafic complex in the Boorara Domain. The Bulong complex consists of 5km thick sequence of komatiitic lava flows made up of a thick serpentinised peridotite in the centre of the complex, flanked by thin spinifex-textured komatiitic flows at the top of the sequence. High-Mg basalts and interflow sediments are intercalated with the thin flow facies komatiites. Komatiitic basalt and high-Mg basalts have a variety of textures which include pillowed, pyroxene spinifex textured and variolitic textured.
A prominent, north – south trending, quartz vein cuts both high-MgO basalts and the Komatiites and extends for at least 1.5km to the south-south-west of Cannon and several smaller quartz veins sub- parallel to the main vein are also present. This quartz vein system has been the focus of past shallow prospecting and mining activities.
The Cannon mineralisation is structurally controlled and strikes north-easterly, dipping steeply to the north-west; higher grade zones within the mineralised envelope appear to have a steep northerly plunge. Gold-related alteration consists of biotite-calcite-chlorite-pyrite alteration with an inner core of albite-silica-carbonate-biotite-pyrite-gold replacement of the high Mg basalt and intermediate intrusions. The Cannon gold deposit is hosted within a sequence of ultramafic and high-Mg basaltic rocks intruded by a mafic-intermediate suite of lamprophyre dykes, and rarer dacitic dykes.
The greenstone sequence strikes N-S and dips steeply west whilst the intrusions strike NNE-SSW with variable dips to the west and east. Early shears and veins dip steeply to the WNW and these are folded and overprinted by a strong S2 foliation that is axial planar to the fold, and dips moderate to the NW. F2 folds plunge 25°?035°. In zones of intense S2 foliation, the earlier formed fabrics become strongly crenulated, dismembered and ultimately transposed by S2. Early talc, carbonate, and quartz-carbonate veins developed within these shear zones probably formed as sets of extension veins, oriented normal to the shear zone (i.e. steep east-dipping) and with ongoing shortening during D2 become folded and then transposed by S2. Within some high-strain shear zones a rare third foliation, a crenulation cleavage S3, is developed. Younger brittle fault events are also noted.
The geology observed within the Cannon open pit comprises variably deformed ultramafic to mafic flows with several felsic – intermediate intrusive bodies. Sedimentary rocks have been observed around the Cannon mine site; however, no sedimentary rocks were observed within the open pit. Ultramafic rocks showed both intrusive and extrusive textures. Komatiitic basalts and high Mg basalts show a variety of textures including pillowed, spinifex and variolitic.
Mineralisation is associated with chlorite-biotite-albite-quartz-carbonate-pyrite alteration. The bulk of the gold mineralisation is hosted in a pillowed basalt unit. Other lithologies present include dioritic intrusives, lamprophyre dykes, high magnesium basalts and komatiites.
The 2021 Cannon Mineral Resource has been estimated over a strike length of 150m (from 6,590,100mN - 6,590,205mN) and a vertical interval of 100m from adjacent to the base of the Cannon pit at 250mRL to 150mRL.
Mineralisation varies in thickness from 1m to 15m with a typical thickness of 5m to 10m.