Airborne geophysical mapping of the Australian continent

Abstract

Many countries have significant coverage of publicly funded airborne magnetic and gamma-ray spectrometric surveys that are available to explorers as precompetitive information to encourage exploration. However, individual surveys are generally small, and after decades of data acquisition, explorers are faced with the problem of how to effectively combine the individual surveys into coherent regional compilations. The Australian government's response was to fly a baseline survey over the whole of Australia at approximately 75-km flight line spacing. This has enabled all of Australia's public-domain magnetic and gamma-ray spectrometric surveys to be leveled to common datums using new techniques facilitated by the baseline control provided by the new traverses. This adds significant value to these data, as they can now be used for the interpretation of regional-scale features and for direct comparison of geophysical signatures from different parts of the continent. Also, quantitative modeling and analysis of the data can now be carried out over much larger areas.

Terrestrial gamma radiation baseline mapping using ultra low density sampling methods

“…While baseline studies of large land areas have been conducted elsewhere (Alharbi et al, 2011;Appleton et al, 2008;Beamish and White, 2011;Bellotti et al, 2008;Green et al, 1992;Minty, 2011;Tracy et al, 1996;Rybach et al, 2012;Wilford et al, 2011;Xiong et al, 2012), there are no publically documented, state-wide radiological baseline data sets available for Queensland, Australia other than those provided in previous aerial radiometric surveys. For a large geographical area such as Queensland, over 1.7 million square kilometres, the cost of representative sediment/soil sampling and radioanalysis of all the identified parameters is significant, and it is reasonable to look to surrogate methods to deliver an alternative means of providing the required data, subject to the method being adequately validated.…”

“…The DAKR map is shown in Fig. 5a, and can be compared, for reference purposes, with the Geosciences Australia aerial radiometric map (Minty, 2011) of Queensland (Fig. 5b) that has been processed using the same classification bands.…”

Minerals geophysics: Preserving industry experience/ Quality control in airborne geophysics

“…Practical implementations of these quality control adjustments show up in the use of the GridMerge tool, (Minty, 2011) where routinely more than 5000 prior TMI surveys are re-adjusted and remerged to make a new coherent representation of the magnetic field. Figure 5 is typical of what is behind most magnetic gridded products in Australia at present.…”

Quality control in airborne geophysics

“…Practical implementations of these Quality Control adjustments show up in the GridMerge tool, Minty (2011) where routinely, more than 5000 prior TMI surveys are readjusted, and remerged to make a new coherent representation of the magnetic field.…”