Geologic and alteration mapping at Mt Fitton, South Australia, using ASTER satellite-borne data

The Japanese ASTER sensor on board the US Terra satellite was launched in December 1999 to establish a spaceborne capability for high spatial, multispectral visible-shortwave infrared and thermal infrared remote sensing data mapping of the Earth’s environment. The Mt Fitton test site in South Australia was chosen to test the ability of the ASTER instrument for geological mapping having been previously surveyed by several visible-shortwave IR and thermal IR airborne remote sensing instruments and several field campaigns collecting relevant spectral measurements. These previous airborne remote sensing surveys and field campaigns successfully mapped a suite of intrusives and sedimentary units with some greenschist metamorphic and localised hydrothermal alteration. Visible-NIR ASTER channels successfully mapped green vegetation and iron oxide information. ASTER SWIR data was spectrally unmixed into four spectrally recognizable endmembers that relate to areas rich in talc, chlorite, white mica and carbonate mineralogies. This result was confirmed using IRIS field spectra resampled to ASTER resolution wavelengths. Quartz, carbonate and talc-tremolite rich units at Mt Fitton were also discriminated using ASTER’s thermal infrared data. These results from low level ASTER data products indicated that ASTER could discriminate mineral groups not achievable from Landsat TM, though more precise mineral species mapping is not possible.