Exploration Geophysics Exploration Geophysics Society
Journal of the Australian Society of Exploration Geophysicists

The Radiometric Map of Australia*

Brian Minty 1 2 Ross Franklin 1 Peter Milligan 1 Murray Richardson 1 John Wilford 1
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- Author Affiliations

1 Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia.

2 Corresponding author. Email: Brian.Minty@ga.gov.au

Exploration Geophysics 40(4) 325-333 https://doi.org/10.1071/EG09025
Submitted: 21 April 2009  Accepted: 13 September 2009   Published: 7 December 2009


Geoscience Australia and the Australian State and Territory Geological Surveys have systematically surveyed most of the Australian continent over the past 40 years using airborne gamma-ray spectrometry to map potassium, uranium and thorium elemental concentrations at the Earth’s surface. However, the individual surveys that comprise the national gamma-ray spectrometric radioelement database are not all registered to the same datum. This limits the usefulness of the database as it is not possible to easily combine surveys into regional compilations or make accurate comparisons between radiometric signatures in different survey areas. To solve these problems, Geoscience Australia has undertaken an Australia-Wide Airborne Geophysical Survey (AWAGS), funded under the Australian Government’s Onshore Energy Security Program, to serve as a radioelement baseline for all current and future airborne gamma-ray spectrometric surveys in Australia.

The AWAGS survey has been back-calibrated to the International Atomic Energy Agency’s (IAEA) radioelement datum. We have used the AWAGS data to level the national radioelement database by estimating survey correction factors that, once applied, minimise both the differences in radioelement estimates between surveys (where these surveys overlap) and the differences between the surveys and the AWAGS traverses. The database is thus effectively levelled to the IAEA datum. The levelled database has been used to produce the first ‘Radiometric Map of Australia’ – levelled and merged composite potassium (% K), uranium (ppm eU) and thorium (ppm eTh) grids over Australia at 100 m resolution.

Interpreters can use the map to reliably compare the radiometric signatures observed over different parts of Australia. This enables the assessment of key mineralogical and geochemical properties of bedrock and regolith materials from different geological provinces and regions with contrasting landscape histories.

Key words: gamma-ray baseline, gamma-ray spectrometry, grid merging, radioelement datum.


Peter Percival (Geoscience Australia) assisted with the preparation of survey data before grid merging. His assistance is gratefully acknowledged. The AWAGS survey was flown by UTS Geophysics Pty Ltd, and funded under the Australian Government’s Onshore Energy Security Program. This paper is published with the permission of the CEO, Geoscience Australia.


Bodorkos, S., Sandiford, M., Minty, B. R. S., and Blewett, R. S., 2004, A high-resolution, calibrated airborne radiometric dataset applied to the estimation of crustal heat production in the Archaean northern Pilbara Craton, Western Australia: Precambrian Research 128, 57–82.
CrossRef | CAS |

Dickson, B. L., and Lovborg, L., 1984, An Australian facility for the calibration of portable gamma-ray spectrometers: Exploration Geophysics 15, 260–262.
CrossRef |

Grasty R. L. , Holman P. B. , and Blanchard Y. B. , 1991, Transportable calibration pads for ground and airborne gamma-ray spectrometers: GSC Paper 90–23, Geological Survey of Canada, Ottawa.

Grasty R. L. , Whitton R. M. , and Duffy A. , 1992, Back calibration and reprocessing of an airborne gamma-ray survey, Malaysia: Expanded Abstracts, 62nd Annual Meeting, Society of Exploration Geophysicists, 550–551.

IAEA, 1987, Preparation and Certification of IAEA Gamma-ray Spectrometry Reference Materials RGU-1, RGTh-1 and RGK-1: Techn. Report-IAEA/RL/148, International Atomic Energy Agency, Vienna.

IAEA, 1990, The use of gamma-ray data to define the natural radiation environment: IAEA-TECDOC-566, International Atomic Energy Agency, Vienna.

IAEA, 1991, Airborne gamma-ray spectrometer surveying: Technical Report Series, No. 323. International Atomic Energy Agency, Vienna.

IAEA, 2003, Guidelines for radioelement mapping using gamma-ray spectrometry data: IAEA-TECDOC-1363, International Atomic Energy Agency, Vienna.

IAEA, 2009, Status of radioelement mapping – towards a global radioelement baseline: IAEA-TECDOC-(in prep), International Atomic Energy Agency, Vienna.

Løvborg L. , 1984, The calibration of portable and airborne gamma-ray spectrometers – theory, problems and facilities: Report Risø-M-2456, Roskilde.

Matolin M. , Minty B. , Barritt S. , and Reford S. , 2005, A global radioelement baseline for gamma-ray spectrometric data: Proceedings Series, Uranium production and raw materials for the nuclear fuel cycle – Supply and demand, economics, the environment and energy security (Proceedings of an international symposium, Vienna, 20–24 June 2005), IAEA, Vienna, 2006, 195–201.

Minty, B. R. S., 2000, Automatic merging of gridded airborne gamma-ray spectrometric surveys: Exploration Geophysics 31, 47–51.
CrossRef |

Minty, B. R. S., Milligan, P. R., Luyendyk, A. P. J., and Mackey, T., 2003, Merging airborne magnetic surveys into continental-scale compilations: Geophysics 68, 988–995.
CrossRef |

Minty B. R. S. , 2006, Towards an Australian radioelement baseline database: Paper presented at the 18th International Geophysical Conference and Exhibition, Australian Society of Exploration Geophysicists, Melbourne, 2–6 July 2006.

Shives R. B. K. , Charbonneau B. W. , and Ford K. L. , 1997, The detection of potassic alteration by Gamma-Ray Spectrometry – Recognition of alteration related to mineralisation. In A. G. Gubins (ed.). Proceedings of Exploration ’97: Fourth Decennial International Conference on Mineral Exploration, 741–752.

Tauchid M. , and Grasty R. L. , 2002, Natural background radioactivity of the earth’s surface – essential information for environmental impact studies. C&S Papers Series 10/P, International Atomic Energy Agency, Vienna, 230–242.

Wilford J. , and Minty B. , 2007, The use of airborne gamma-ray imagery for mapping soils and understanding landscape processes. In ‘Developments in Soil Science – Volume 31: Digital Soil Mapping – An Introductory Perspective’. P. Lagacherie, A. B. McBratney and M. Voltz (eds). (Elsevier.)

* *Presented at the 20th ASEG Geophysical Conference and Exhibition, February 2009.

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