Exploration strategies for detecting high-grade (>55 wt. %) iron ore in the Pilbara Craton have historically relied upon the identification of exposed supergene hematite-goethite-rich orebodies. However, exploration in some parts of the Pilbara is now reaching a mature state in that discovery success is slowing using the current exploration model. The opportunity now exists to develop a more predictive exploration strategy for the Pilbara Craton using innovative techniques; a strategy that targets (1) near-surface supergene hematite-goethite ore, (2) deeper extensions of hypogene magnetite-rich ore and genetically related alteration zones, and (3) the detection of “blind” supergene and/or hypogene orebodies beneath surface transported cover and unmineralised BIF.
The key to this predictive approach to exploration lies in first establishing the geological criteria that controls the location of high-grade iron orebodies within an iron ore camp and then extrapolating these findings to other camps and the remainder of the Pilbara Craton. Integrated spectral analytical techniques (HyLogger, ASTER, Hymap surveys) will be used in conjunction with detailed field and laboratory studies (mapping, core examination, petrographic description, fluid inclusion studies; whole rock, trace element, REE geochemistry and isotopic analysis of rocks and minerals) to characterise supergene and hypogene iron ore types and their related alteration mineral assemblages. A similar research methodology has recently been successfully applied for iron deposits in the Yilgarn Craton (e.g. at Koolyanobbing/Windarling, Angerer and Hagemann 2010; Angerer et al. 2012; Weld Range, Duuring and Hagemann 2012a; Duuring and Hagemann 2012b). These studies demonstrate the importance of camp-scale geological processes in controlling iron ore type (i.e. Fe grades and contaminants) and how this knowledge may translate to tangible benefits to exploration programs (e.g. the application of remote hyperspectral studies for the identification of iron ore, Duuring et al. 2012).
The project is co-sponsored by Industry, GSWA, MERIWA and is managed by the Centre for Exploration Targeting. Major outcomes of the applied research include:
new structural, mineralogical, geochemical, geophysical and spectral data sets for a variety of BIF-hosted deposits in the Pilbara Craton;
integrated, multi-scale, genetic model(s) that explain(s) processes (and their absolute and relative timing) leading to formation of various types of iron ore deposits;
an expanded detectable footprint for supergene and hypogene iron ore; and
a revised exploration model that targets supergene and hypogene iron ore, including “blind” iron orebodies.