Extracting mineralogical and geomorphological information using new ASTER mineral maps with airborne geophysics

Abstract

Australia wide maps have recently been generated and released by CSIRO and Geoscience Australia using the 14 band satellite-borne ASTER sensors. Seventeen map products related to surface composition have been developed, based on spectral absorption features representing either abundance of mineral groups, specific minerals and their chemistry, vegetation cover or regolith related characteristics. This study aims to test the geoscience mapping capabilities of these products, individually, and integrated with airborne geophysics and DEMs over the semi-arid Mt Fitton, South Australia, and within the agricultural Wagga Wagga region, New South Wales. The robustness of these techniques is further tested comparing the results from these two areas with different geological exposure and cultivation. Various image processing, GIS and principal component analytical techniques were utilised. High resolution airborne hyperspectral imagery and published mapping provided control. ASTER map products : Ferric Oxide Content, Ferrous Iron Index, AlOH Group Content, FeOH Group Content, MgOH Group Content & Composition, Ferrous Iron Content in MgOH, and Silica Index products revealed surface mineral composition associated with previously mapped host or altered units of Mt Fitton. MgOH Group Composition and Ferrous Iron in MgOH products highlighted anomalies associated with Mt Fitton talc/tremolite metasomatism. The AlOH Group Content and Ferrous Iron Index products discriminated the radiometrically anomalous Terrapinna and Yerila Granites whilst DEM information enabled the discrimination between ASTER Silica Index defined quartz rich alluvium and outcrops. These results showed that within the semi-arid Mt Fitton environment, ASTER map products were useful for the identification of the mineral(group) composition related to either the host rock units or altered mineralogy. Integration of ASTER products with airborne radiometric, magnetics and DEMs refined the interpretation of the surface geology and associated landforms.