The use of airborne gamma-ray spectrometry - A case study from the Mount Isa inlier, northwest Queensland, Australia

An airborne survey was undertaken on the Mount Isa inlier in 1990-1992. During this survey, both airborne magnetic and gamma-ray spectrometric data were recorded over 639 170 line-km. Because of perceived value of the radiometric data, stringent calibration procedures, including the creation of a test range, were adopted. In addition to the data from the newly-flown areas, 76 760 line-km of existing data were acquired from other companies, and were reprocessed and merged with the Mount Isa survey. The total area covered by the Mount Isa airborne survey was 151 300 km(2). Over the last five years, several studies have been undertaken that seek to exploit the Mount Isa region gamma-ray database and maximise the use of radiometrics for mineral exploration. This paper highlights the results of these studies by focussing on radiometric signatures of major mines in the Mount Isa Inlier, radioelement contour maps, geomagnetic/radiometric interpretation maps, lithological mapping, regolith mapping, geochemical sampling, and spatial modeling using geographical information systems (GIS). Due to the recent introduction of GIS technology and better techniques for handling high quality digital data, there has been a revived interest in making more use of image data sets. The integration of raster and vector data sets for both spectral and spatial modeling has maximized the potential of this approach.