Summary:
Mineralisation at both Minyari and WACA is hosted predominantly within hydrothermally altered metasediments. There are several mafic bodies identified in the project area, predominantly dolerite, which are variably mineralised, along with late felsic intrusive dykes that cross-cut the deposit area and are generally unmineralised. The resource has been depleted in these lithologies. The Proterozoic rocks are overlain by transported overburden, typically desert/dune aeolian sand which varies in thickness up to 10 metres.
The Minyari and WACA deposits precious (gold and silver) and/or base metal (copper and cobalt) mineralisation is interpreted to be reduced intrusion-related, with local controls on mineralisation related to variations in both the competency/hardness and chemical composition of rock units, in combination with other discrete structural controls such folding, faulting, fracturing, veining, brecciation and associated hydrothermal alteration and mineralisation (including sulphides) being the key factors influencing mineralisation grade and continuity.
The Minyari deposit constitutes approximately 85% of the gold resource and 96% of the Scoping Study mining inventory gold ounces. Minyari mineralisation is generally moderate to steeply dipping and is hosted by a plunging pipe-like breccia body located in the hinge and both limbs of an interpreted synform. The true-thickness of mineralisation ranges from 5 to 120m and extends from surface to a depth of 670m and remains open down plunge to the northwest. In the Minyari deposit area there is also near-surface, sub-horizontal soil/calcrete hosted re-worked/remobilised “channel” style low-grade gold mineralisation, located above the Proterozoic basement.
Dimensions
At Minyari Dome several styles of mineralisation were identified:
Minyari
Sub-horizontal soil/calcrete hosted re-worked / remobilised “channel” style low-grade gold mineralisation located above the Proterozoic basement which extends for 200 to 350m north-south, 10 to 185m east-west and with a true width ranging from 1.5 to 5.0m.
Proterozoic basement (meta-sediment and metaintrusive) hosted breccia style high-grade gold-coppersilver-cobalt mineralisation typically preferentially hosted by certain meta-sedimentary lithologies which form the main components of a moderate northwesterly plunging synformal fold structure (i.e. western and eastern limbs and fold nose) and also pre-mineralisation felsic to mafic dykes and sills, all of which have been strongly overprinted by shallow to steeply dipping mineralised and hydrothermally altered faults, fractures, veins and breccias some bearing significant sulphides.
Western limb hosted mineralisation is approximately vertical with a strike length of up to 500m, a true width of between 20 to 120m, extending to 660m below the surface and remaining open down plunge;
Eastern limb and fold nose hosted mineralisation is moderate west and shallow northwest dipping respectively with a strike length of up to 500m, a true width of between 5 to 80m, extending to 660m below the surface and remaining open down plunge.
Minyari Inclined lodes – twenty seven, steeply dipping near vertical mineralised lodes proximal to the breccia zone and loosely paralleling the local structural interpretation. These lodes vary between extending from surface for 225m vertically to commencing 260m belove surface and extending to 800m below surface. The inclined lodes have a strike length of 70 to 200m, extend between 120 to 320m vertically, and have an average true width of 1 to 10m. The inclined lodes remain open at depth.
Sundown
Comprises six parallel lodes dipping steeply to the west – southwest. Mineralisation extends from surface down to 330m below surface with a vertical extent of between 100 to 330m, along a strike length of between 50 to 250m, and with an average true width of between 1 and 9m.
GEO -01
Comprises multiple lode style mineralisation envelopes. Mineralisation commences approximately 10 metres from the surface and extends down greater than 500 vertical metres, with an average depth extension of 220 metres, along a strike length of between 150m to 600m, and with an average true width of 1m.
Minyari North deposit
Comprises eight parallel lodes dipping steeply to the east-northeast. Mineralisation extends from the base of cover down to 300m below surface with a vertical extent of between 50 to 300m, along a strike length of between 60 to 260m, and with an average true width of between 1 and 8m.