The Challenger Gold Deposit area lies in the northern Gawler Craton. The gold deposit and surrounding area exemplify regolith-landform relationships of the northern Gawler Craton.

The northern Gawler Craton has been affected by extensive and prolonged tectonism, but a significant proportion of the region retains Archaean to earliest Proterozoic radiometric ages. Archaean metasediments of the Mulgathing Complex were derived at least in part from pre existing continental basement, and include banded iron-formation (BIF), chert, carbonate, calc silicate, quartzite and aluminous sediments. Komatiite and tholeiitic basalt flows are inferred to be contemporaneous with sedimentation.

The Challenger area consists predominantly of the Christie Gneiss, which is a compositionally layered granulite facies metasediment. The most prominent and persistent type of outcrop in the region is BIF, which, in places, has been complexly folded and oxidised to haematite goethite gneiss. The BIF has a typical composition of quartz-magnetite-diopside plus hypersthene, with accessory apatite and Fe sulphide. The gneiss also contains bands of pink microcline-quartz-plagioclase-gamet and layers of carbonate with accessory garnet, clinopyroxene and olivine.

The Challenger resource models were used to create detailed life of mine (LOM) designs for the extraction of each resource lode. The design was based around an uphole retreat, top down stoping sequence. This mining technique has been used in the past, and will be used in the future.

Mining of the narrow vein Challenger lodes has been designed with a minimum mining width of 1.5m. Based on historical mining at Challenger an external dilution of 40% has been applied in the calculation of all reserves, unless the development has been completed and a full stope analysis has been produced indicating variations to this dilution based on geotechnical input. A specific stope extraction factor has been applied to each level in the reserve estimation, based on the geological resource model, geotechnical requirements and the extraction sequence of each orebody shoot.

Mining and processing operations at Challenger have been conducted since 2001. Although there was a temporary suspension of operations from 15 March 2016 to early May 2016 when operations recommenced under WPG’s management, Challenger is a mature operation with reliable historical data.

The existing Challenger CIP and gravity processing facility will be utilised to extract the gold. The performance of this plant is well understood.