Case Studies of 21st Century Exploration Success
The Nova-Bollinger deposit is a large nickel-copper sulfide deposit discovered in 2012 by a junior Australian exploration company, Sirius Resources. The deposit is interpreted to represent a magmatic sulfide accumulation within several stacked mafic sills that intruded a sequence of sedimentary rocks, which has been subsequently recrystallized and variably deformed by lower granulite facies metamorphism. The deposit is located in the Albany-Fraser orogen of Western Australia—a Proterozoic belt broadly similar to the Circum-Superior belt in North America, which hosts the Thompson and Raglan nickel mining camps. Although some previous explorers had recognized the similarity between these areas and also undertaken limited exploration for nickel, the prospectivity of the Albany-Fraser orogen for magmatic nickel deposits was largely unrecognized and the area was virtually unexplored prior to the involvement of Sirius.
The discovery is somewhat unusual because it is a blind, grassroots discovery made in what was previously assumed to be an unendowed geologic terrane by a small company with a small exploration budget. It is also unusual because the style of deposit discovered was exactly that which was originally targeted. The case study of the discovery includes the geologic concept, the exploration methods, and the key circumstances that led to the discovery of Nova-Bollinger. In one sense the discovery represents a textbook example of the deliberate and successful application of good geologic science and appropriate exploration methodology, but in another sense it was the culmination of numerous key decisions and seemingly unrelated events that spanned a period of nearly fifty years that created the necessary building blocks for the ultimate success. These building blocks include the involvement of a variety of other elements, including the efforts of previous mining companies, an accident by NASA, the persistence of a wealthy Australian prospector, and the initiative of the Government and Geological Survey of Western Australia.
In terms of process, the deposit was discovered by systematically using various methods that were tailored to the target style and the nature of the terrane, and also appropriate to the scale and stage of exploration. These comprised regional aeromagnetics for target definition, soil geochemistry for target verification and prioritization, shallow reconnaissance drilling for defining the source of soil anomalies, ground electromagnetic geophysics for defining discrete drill targets, and finally drilling. It is critical to also evaluate how information and misinformation can potentially affect the exploration process at every step, and how entirely extrinsic factors such as timing and luck can determine the outcome of the process. Of particular interest in the case of the Nova-Bollinger discovery is insight into how junior explorers operate compared to the bigger companies, what they have to do to be effective explorers, how they contribute to the overall well-being of the resources sector, and how their success is influenced by the degree to which three factors coincide—motive, means, and opportunity.