Summary:
Geology and Mineralisation
The CCP copper-gold mineral deposits are located in the Eastern Fold Belt (EFB), one of three major tectonic units that make up the Proterozoic Mount Isa Inlier8. The EFB is a poly-deformed, Paleo-to Meso-Proterozoic orogenic belt with a protracted depositional, tectonic and metasomatic history. The mainly volcanic and sedimentary rocks in the belt were deposited in a series of intracontinental basins that unconformably overlie older, previously deformed and metamorphosed basement. Mineralisation is associated with hydrothermal activity related to granite emplacement during orogenesis9. The region is host to many significant mineral deposits including Broken Hill Type (BHT, e.g. Cannington) and Iron-Oxide-Copper-Gold (IOCG, e.g. Ernest Henry, Osborne, Eloise, Selwyn, Great Australia, Roseby, E1 and Taipan).
Great Australia Mine
Great Australia and Orphan Shear projects are located adjacent to, or within, a regional north-south trending structure, the Cloncurry Fault (locally called the Orphan Shear). This regional structure extends from north of Cloncurry southwards for approximately 150 kilometres. The Cloncurry Fault forms a regional tectonic contact with the metasedimentary Corella Formation and is an important structural control to mineralisation within the EFB9. The north-south trending Cloncurry Fault separates the andesite, dolerite, basalt, shales and minor limestones of the Toole Creek Volcanics (TCV) of the Soldiers Cap Group to the west, and Corella Formation (CF) calc-silicates of the Mary Kathleen Group to the east, within the Orphan Shear/Great Australia area. The CF in the mine area comprises pink-grey bedded to massive calc-silicate meta-carbonate and meta-siliciclastic sediments that may be strongly brecciated. A regional brecciated unit, the Gilded Rose Breccia, features in the mine area and is generally associated with the contact between TCV and CF rocks, although it intrudes the TCV in several places. Mineralisation at GAM and Orphan Shear is associated with skarn like assemblages of actinolite and magnetite alteration. Mineralisation is mostly hosted in steep north easterly trending sulphide veins/veinlets zones with flatter mineralised zone developed shallow in the deposits. Gangue within the veins includes pyrite, carbonates, actinolite and chlorite. Oxide and transitional mineralisation in the form of malachite, tenorite and chalcocite is observed in the weathered zones of the deposit, which is limited generally to a 10-20m ‘cap’ on the top of the deposits. Sulphide mineralisation consists of chalcopyrite hosted include carbonate, quartz, and pyrite in veinlets and semi-massive sulphide vein breccias. Chalcocite is the dominate copper mineral in the transitional weathering zone. Mineralisation in the oxide zone close to surface is dominated by malachite with minor tenorite. Native copper is observed sporadically along the trend within both the oxide and transitional zones. Taipan mineralisation is hosted within the Toole Creek Volcanics, approximately 600m west of the projected trace of the Cloncurry Fault and the western limit of the Great Australia mineralisation. Taipan is modelled as a series of shallow northeast dipping sheet like bodies of crackle-breccia and/or stockwork veinlets principally infilled by chalcopyrite and actinolite, with lesser magnetite, pyrite, and carbonate minerals. Mineralisation at Taipan has a thin zone of 1-5m of oxide copper mineralisation.
Wallace North
Wallace North deposit consists of sulphide-rich copper-gold mineralisation contained within a poorly exposed shear zone that trends ENE-WSW with a steep WNW to vertical dip. Wallace North is of the Iron Sulphide Copper Gold (ISCG) class of mineral deposits. Mineralisation within the Wallace North shear zone occurs as two main sub-vertical ENE-WSW tabular zones and several additional minor zones of mineralisation semi-exposed over about 100m. Mineralisation extends under cover along strike in both directions. Mineralisation in the area is focused in a structurally complex area where mafic volcanic (metabasalt) and sedimentary (calcareous siltstone and mudstone, black shale) rocks of the Toole Creek Volcanics (Soldiers Cap Group) are folded about an E-W-trending, regional-scale anticline (possibly the Mountain Home Anticline) and cut by a NW-SE-striking fault that is connected to a more substantial, >20 km-long, N-S-striking fault. Much of the project area is covered by Quaternary sediments of the Elder Creek drainage system. Fresh unweathered mineralisation consists of chalcopyrite hosted include carbonate, quartz, and pyrite in veinlets and semimassive sulphide vein breccias. Chalcocite is the dominate copper mineral in the transitional weathering zone. Mineralisation in the oxide zone close to surface is dominated by malachite with minor tenorite. Native copper is observed in sporadically along the trend within both the oxide and transitional zones.