Greenfields Exploration is the process whereby broad target areas are selected on the basis of favourable geology and/or geophysics with little or no evidence of the target mineralisation. It relies strongly on empirical models coupled to an understanding of the relevant tectonic settings, mineralising processes, and effective use of geochemistry and geophysics to define specific targets within these areas.

The aim of this theme is to contribute to an emphatic and continuing improvement in the risk : reward ratio in Greenfields Exploration through more effective selection and testing of target areas. The initial emphasis will be exploration for orogenic and intrusion-related gold, sulphide nickel, BIF-hosted iron ore, and iron oxide copper-gold deposits. Particular attention will be given to the development of collaborative and synergistic relationships with pmd*CRC programs in WA, and to the exciting advances in modelling of the crust through joint inversion.

Issues and Challenges

Greenfields Exploration is inherently higher risk than Brownfields Exploration. Nevertheless, the advantages of making the first discovery in a new camp or district, and the fact that the largest deposit is usually found first, have always encouraged a substantial proportion of Greenfields activity. Over the period from the late 1960s to the early 1990s, the discovery rate in WA (and globally) had been sufficient to offset the high risk. However, the sharp decline over the last decade, coupled with industry issues such as consolidation, more disciplined use of investment capital, and the resulting cuts in exploration expenditure, have resulted in sharp falls in Greenfields expenditure in WA. It is estimated that since 1997 this expenditure has fallen by almost two-thirds, because the proportion of Greenfields activity has declined from 40% in 1997, to only 28% in 2001.

The State’s mineral industry is largely based on the Greenfields Exploration successes of past eras. However, the declining rate of discovery in WA, and the accompanying deterioration in the risk : reward ratio has coincided with a period when other factors have made the exploration industry more risk averse. To break this nexus, outputs are required that will result in much more effective selection and testing of target areas, and an emphatic and continuing improvement in the risk : reward ratio. The emphasis will be on covered terranes, where the highest potential for the discovery of new mining centres is believed to exist.

Outputs, Outcomes and Strategies

• Improved pragmatic, empirical models based on extensive data sets at scales ranging from district/terrane scale, up to global, that identify the footprints of mineralisation and the interdependence of critical parameters such as tectonic setting, geology, geometry, geochronology, size distribution, cluster characteristics, grade variability and quality. There will be particular emphasis on those parameters which appear to influence the size, quality and location of new centres of mineralisation.
• Correlations between the critical model parameters and the 3D architecture of the lithosphere.
• Compilations (in 3D) of the geophysical and geochemical signatures associated with camp/district scale centres of mineralisation, including both primary and secondary expressions.
• Practical exploration tools based on integration of the above outputs with outputs from Progressive Risk and Value Analysis.
• Graduates with strong training in basic geology, data integration and the pragmatic application of targeting research to mineral exploration.

As in Brownfields Exploration, these outputs will be of direct value to industry. Improved empirical models and signature recognition will lead to better target selection and, when combined with risk and value assessment, should result in more cost-effective exploration. To achieve these key outputs, the following strategies will be employed:

• Work across a wide range of scales, from district up to global.
• Establish a strong geological foundation and framework to empirical data sets and models, based on critical observations in the field.
• Complement and utilise the work of pmd *CRC; provide additional data for its computational modelling and process models; avoid overlap. Utilise the capacities available in ESMG.
• Encourage and engage in collaborative research that will enhance CET’s capacity to deliver these outputs, especially in regard to: the regolith expression of primary geochemical signatures (with CRC LEME);, the regional and tectonic setting of deposits and centres of mineralisation (with TSRC, GEMOC, Geoscience Australia and GSWA); and effective visualisation of the results in 3D.

Actions and Resources

Research activities will parallel those outlined for the Brownfields Exploration theme, but with increased emphasis on identifying key attributes of the tectonic setting across a range of scales. They will also assess the relationship between the structure and evolution of the lithosphere and crust and mineralising events in the Earth’s history through collaboration with TSRC and GEMOC.

It is anticipated that around 20% of the Centre’s resources will be devoted to this theme area; the pro tem theme leader will be Professor David Groves.

Possible Projects

• Compile the geological, geochemical and geophysical signatures (or footprints) of major centres of gold and sulphide nickel mineralisation in WA (through data compilation and field observations).
• Analyse the size and shape distributions of deposits, and their cluster characteristics*.
• Identify the critical factors that control the variation and distribution of ore quality.
• Identify vectors to ore at the camp scale*.
• Develop criteria for early recognition of world class mineralised systems in drill testing of targets.
• Compile an “atlas” of the tectonic regimes associated with different types of deposits and their geological characteristics; emphasise diagnostic factors which enable recognition of these regimes.
• Undertake field documentation of critical parameters to strengthen models.
• Develop new insights into the relationship between metallogeny and secular global evolution for application in exploration.

* This may utilise modelling technologies from ESMG.