Abstract
Abstract. The integration of surface and subsurface geoscience data is critical for efficient and effective mineral exploration and mining. Publicly accessible data sets to evaluate the various geoscience analytical tools and their effectiveness for characterisation of mineral assemblages and lithologies or discrimination of ore from waste are however scarce. The open-access Rocklea Dome 3D Mineral Mapping Test Data Set (Laukamp, 2020; https://doi.org/10.25919/5ed83bf55be6a) provides an opportunity for evaluating proximal and remote sensing data, validated and calibrated by independent geochemical and mineralogical analyses, for exploration of channel iron deposits (CIDs) through cover. We present hyperspectral airborne, surface, and drill core reflectance spectra collected in the visible–near-infrared and shortwave infrared wavelength ranges (VNIR–SWIR; 350 to 2500 nm), as well as whole-rock geochemistry obtained by means of X-ray fluorescence analysis and loss-on-ignition measurements of drill core samples. The integration of surface with subsurface hyperspectral data collected in the frame of previously published Rocklea Dome 3D Mineral Mapping case studies demonstrated that about 30 % of exploration drill holes were sunk into barren ground and could have been of better use, located elsewhere, if airborne hyperspectral imagery had been consulted for drill hole planning. The remote mapping of transported Tertiary detritals (i.e. potential hosts of channel iron ore resources) versus weathered in situ Archaean bedrock (i.e. barren ground) has significant implications for other areas where “cover” (i.e. regolith and/or sediments covering bedrock hosting mineral deposits) hinders mineral exploration. Hyperspectral remote sensing represents a cost-effective method for regolith landform mapping required for planning drilling programmes. In the Rocklea Dome area, vegetation unmixing methods applied to airborne hyperspectral data, integrated with subsurface data, resulted in seamless mapping of ore zones from the weathered surface to the base of the CID – a concept that can be applied to other mineral exploration and mineral deposit studies. Furthermore, the associated, independent calibration data allowed the quantification of iron oxide phases and associated mineralogy from hyperspectral data. Using the Rocklea Dome data set, novel geostatistical clustering methods were applied to the drill core data sets for ore body domaining that introduced scientific rigour to a traditionally subjective procedure, resulting in reproducible objective domains that are critical for the mining process. Beyond the previously published case studies, the Rocklea Dome 3D Mineral Mapping Test Data Set has the potential to develop new methods for advanced resource characterisation and develop new applications that aid exploration for mineral deposits through cover. The white mica and chlorite abundance maps derived from airborne hyperspectral, presented here for the first time, highlight the additional applications of remote sensing for geological mapping and could help to evaluate newly launched hyper- and multispectral spaceborne systems for geoscience and mineral exploration.
Highlights
The three-dimensional (3D) geologic case history of the Rocklea Dome located in the Hamersley Province (Western Australia) targeted the use of reflectance and emission spectroscopy for measuring mineralogy and geochemistry specific to the exploration and characterisation of economic Tertiary channel iron ore deposits in a terrain obscured by weathered, transported materials
We have established an open-access data set comprising drill core, surface, and airborne hyperspectral data of the Rocklea Dome area in the Hamersley Basin of Western Australia, which features a wide variety of lithologies and morphologies and is prospective for channel-hosted iron ore resources
The interpolated model of the base of the channel iron system calculated using the 3D kaolin crystallinity map is shown by the shaded grey surface
Summary
The three-dimensional (3D) geologic case history of the Rocklea Dome located in the Hamersley Province (Western Australia) targeted the use of reflectance and emission spectroscopy for measuring mineralogy and geochemistry specific to the exploration and characterisation of economic Tertiary channel iron ore deposits in a terrain obscured by weathered, transported materials This public case history was generated by CSIRO’s Western Australian Centre of Excellence for 3D Mineral Mapping (C3DMM), which was operated from 2009 to 2012 and had the primary aim of generating and demonstrating the capabilities for “scalable” 3D mineral mapping from the continental to the prospect scales (Cudahy, 2016). This represents potential significant savings in time, money, and environmental disturbance
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