The Perseverance Gold Copper Deposit – A New Peak Mines Challenge

摘要

The Perseverance deposit is the most southerly known economic copper/gold deposit within thernCobar gold fi eld. The deposit is situated approximately 12 km to the south-southeast of Cobarrnand is essentially blind to surface with the top of economic mineralisation occurring 750 m belowrnground level.rnBased on the December 2010 resource estimate (inclusive of reserves and net of depletion) therndeposit contains 3 011 000 tonnes at 6.1 g/t Au and 0.90 per cent Cu (590 000 oz of gold andrn28 000 tonnes of copper).rnThe deposit is comprised of four principal lenses, the Perseverance, Hulk, Zone B, and Herculesrnlenses. In excess of 90 per cent of the known resource tonnes are contained within the Perseverancernand Hulk lenses.rnThe deposit is shear related and hosted within lower Devonian rocks of the Cobar Basin. Therncompetency contrast of rhyolites juxtaposed against sediments by the Peak-Perseverance shearrnis the principal control on mineralisation. Both the Perseverance and Hulk lenses are primarilyrnhosted by brecciated rhyolites juxtaposed against Chesney formation sediments across the Peak-rnPerseverance shear. This faulted rhyolite sediment contact roughly defi nes the global orientationrnof the deposit. The Perseverance lens continues within the shear for up to several hundred metresrnbeyond the extent of the faulted rhyolite sediment contact. Mineralisation within the shear beyondrnthe faulted rhyolite contact zone is hosted by sheared silicifi ed sediments. The Perseverance lensrnremains open at depth and to the south.rnThe Zone B and Hercules lenses, which are signifi cantly less important in tonnage terms, arernhosted by rhyolite breccias within the main body of the rhyolite and appear to be only tenuouslyrnrelated to the Peak-Perseverance shear.rnWithin the Perseverance lens, the presence of northeast trending high grade breccia veinsrndeveloped oblique to the north-south trending shear system has led to the development of steeplyrnnorth plunging high grade ore shoots within a globally north-south trending mineralised domain.rnThese high grade shoots have limited horizontal continuity but signifi cant down plunge extent.rnThe presence of coarse gold and the resulting strongly skewed nature of the gold grades, inrnconjunction with controls on mineralisation which are not parallel to the mineralised domain, hasrnled to predictive diffi culties regarding stope performance.rnStrong heterogeneity of the gold content of the ore and geological controls on mineralisationrnwhich are not parallel to the global trend of the mineralisation impose a set of diffi culties whichrnsound geological control is helping overcome.