Mineral exploration and geoscientific analysis

Mineral exploration and geoscientific analysis

The first and to date only geoscience-tuned Earth observation (EO) system that has acquired complete coverage of the Australian continent is the Japanese ASTER (Advanced Spaceborne Thermal Emission and Reflectance Radiometer -...

The first and to date only geoscience-tuned Earth observation (EO) system that has acquired complete coverage of the Australian continent is the Japanese ASTER (Advanced Spaceborne Thermal Emission and Reflectance Radiometer - http://asterweb.jpl.nasa.gov) system. ASTER was launched in December 1999 onboard the USA's Terra satellite (http://terra.nasa.gov, NASA's Earth Observing System, 2011). This multispectral satellite system has 14 spectral bands spanning: the visible and near-infrared (VNIR - 500-1000 nm - 3 bands @ 15 m pixel resolution); shortwave-infrared (SWIR - 1000-2500 nm range - 6 bands @ 30 m pixel resolution); and thermal infrared (TIR 8000-12000 nm - 90 m pixel resolution) atmospheric windows in a polar-orbiting, 60 km swath (Abrams et al., 2002). However, the ASTER spectral bands do not have sufficient spectral resolution to accurately map the often small diagnostic absorption features of specific mineral species, which can be measured using "hyperspectral" (hundreds of spectral bands) systems (http://speclab.cr.usgs.gov/hyperspectral.html). Thus ASTER data can only be used to map mineral groups, such as the di-octahedral "Al-OH" group comprising the mineral sub-groups (and their minerals species) like kaolins (e.g. kaolinite, dickite, halloysite), white micas (e.g. illite, muscovite, paragonite) and smectites (e.g. montmorillonite and beidellite). CSIRO's Australian ASTER Geoscience Map initiative with the government geosurveys across Australia began in the 1990's though it was not until late 2009 that this opportunity became achievable when access to the complete archive of ASTER imagery over Australia was secured (http://c3dmm.csiro.au/ASTER%20Map%20of%20Australia%20EOI%20flyer.pdf). This National initiative is now supported by State, Territory and Federal government geoscience agencies across Australia as well as the ASTER Science Team (http://www.science.aster.ersdac.or.jp/en/science_info/index.html), ERSDAC, NASA-JPL, United States Geological Survey and Auscope Grid (http://www.auscope.org.au/site/grid.php). This South Australian ASTER Geoscience Map is the second State-wide release for Australia though is the first to publicly release geosciences products generated from ASTER's TIR bands. It follows on from smaller development and testing projects on the Mount Isa Block in Queensland and the Gawler-Curnamona Blocks in South Australia promoted by Geoscience Australia. These maps should be considered as "Version 1", acknowledging that there remain significant opportunities to improve on the accuracy (seamlessness) of the methods/products in later updates.

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