Gawler Craton - Economic Geology

Economic Geology

Minerals that have been found in the craton include gold, diamonds, copper, nickel, granite, iron ore, lead-zinc, uranium, coal, industrial minerals and arsenic.

The huge Olympic Dam copper-gold operation is located in the Eastern Olympic Copper-Gold Province at the cratons eastern edge. The Prominent Hill copper-gold mine is northwest of Olympic Dam and the Challenger Gold Mine is to the west of Prominent Hill located in the center of the craton. The 70 million tonne Kalkaroo Mine is to the south and contains approximately 320,000 tonnes of copper, 1 million ounces of gold and 8.56 million kg of molybdenum in an optimized open pit designed to 230 metres depth (Havilah, 2006).

The Wynbring area, a large part of the western Fowler Domain, covers approximately 2,000 square kilometres and consists of fractures that may include intrusion of mafic-ultramafic bodies with potential for nickel sulphides, chromite and platinoids. Exploration and regional drilling near the northern end of the Fowler Domain and within the Harris Greenstone Belt has identified numerous large mafic and ultramafic bodies which have the potential to host nickel sulphide mineralization. Ultramafic intrusive rock hosting nickel bearing sulphides (pentlandite and mackinawite) has returned values up to 0.49% nickel, 38 parts per billion(ppb) platinum and 58ppb palladium. Previous explorations reported up to 0.74% nickel from samples obtained in shallow bedrock drilling (Mithrill Resources, 2005). The Thompson Belt in Canada has similar features and is considered by the Department of Primary Industries and Resources South Australia (PIRSA) as a possible analogue of the Fowler Domain. The Thompson Nickel Belt hosts major nickel deposits which have been mined by Inco since the early 1960s. Previous explorations in the Wynbring area consisted of wide-spaced reconnaissance bedrock drilling by PIRSA that indicated the presence of a 30 kilometre-long zone of intermediate to ultramafic rocks adjacent to a major fault and geochemically anomalous in gold, nickel, chromium, platinum and palladium. (PlatSearch, 2004).

Drilling has confirmed significant widespread uranium mineralisation at the "Warrior" paleochannel in central Gawler just west of Prominent Hill and there is active uranium exploration over an extended portion of the Kingoonya Palaeochannel system within the southern Gawler Craton. "Warrior" is the most significant known uranium occurrence in the Gawler Craton. (Stellar, 2006).