Unmixing the effects of vegetation in airborne hyperspectral mineral maps over the Rocklea Dome iron-rich palaeochannel system (Western Australia)

Abstract

Quantitative iron (oxyhydr-)oxide (Fe-Ox), AlOH-clay and carbonate abundance maps of the Rocklea Dome in Western Australia have been derived from hyperspectral visible-near to shortwave infrared (VNIR–SWIR) airborne data that were compensated for the influence of vegetation cover. The quantitative mineral maps were validated against field data, including ~5500 VNIR–SWIR spectra and ~300 portable X-ray fluorescence measurements. The error on these airborne mineral abundance estimates averages 13.4wt.% Fe for the Fe-Ox abundance, 4.0wt.% Al2O3 for the AlOH-clay abundance and 0.025 for the 2320D parameter used to quantify the carbonate abundance. The unmixed quantitative mineral abundance maps improve geological mapping, including characterisation and exploration for channel iron deposits (CID). In particular, some areas with outcropping CID, which appear subeconomic from the airborne Fe-Ox abundance map without vegetation removal, show as potentially economic CID resources when the influence of vegetation cover is unmixed from the airborne hyperspectral data. These results show that seamless maps of mineral contents can be achieved using data collected from both proximal (drill core and field) and remote (airborne and satellite) hyperspectral sensing systems.