Uranium

Geophysics for Uranium

Stephen Mudge has been applying a variety of geophysical techniques to uranium exploration in Australia and Canada since the late 1970s. In addition, a range of data-processing techniques have been developed and tested in an attempt to detect the geophysical responses of the various types of uranium deposits and their host environments.

The fastest and most cost-effective geophysical method for broad- area exploration for uranium deposits is surveying with low-level, high-resolution aeromagnetics and radiometrics. Obviously, radiometric surveying is highly effective for detecting and mapping gamma-ray radiation from outcropping uranium deposits.

Conventional data processing techniques (such as channel ratios, ternary plots etc) applied to the uranium and associated potassium and thorium radiometric channels, are very effective for resolving subtle radiometric responses associated with sub-cropping uranium deposits.

Specialised data processing techniques are applied to the aeromagnetic data using TargetMap^TM in order to resolve the magnetic responses of structures in the host rocks and the basement rocks. These maybe associated with depositional traps for uranium.

Airborne electro-magnetics (EM) is also a fast and often effective geophysical method for broad-area exploration for uranium deposits. A variety of airborne EM systems are available and have been applied to map electrical conductivity sometimes associated with roll-front and calcrete type uranium deposits. In addition, airborne EM surveying is used to detect and map conductive carbonaceous and graphitic rocks sometimes associated with uranium deposits. In all cases, specialised data processing techniques are applied to the electro-magnetic data using TargetTEM^TM in order to resolve the subtle conductive responses of the uranium deposits and their host rocks.

Details of TargetMap^TM and TargetTEM^TM can be found elsewhere on this web site. A number of airborne transient electro-magnetic (TEM) surveys from Australia and Canada, using the GEOTEM, MEGATEM, TEMPEST, HOISTEM and AeroTEM systems, have been processed with TargetTEM^TM to detect and map conductivity associated with uranium deposits, their host rocks, and their depositional environments. The magnetic data from these and other surveys have been reprocessed with TargetMap^TM.

References

Here are references to two very good papers describing the applications of a variety of modern geophysical techniques to uranium exploration.

Root, J. C. and Robertson, W. J., 1994. Geophysical signature of the Kintyre uranium deposit, Western Australia. In, Dentith M.C., Frankcombe, K. F., Ho, S. E., Shepherd, J. M., Groves, D. I. and Trench, A., (Eds.), Geophysical Signatures of Western Australian Mineral Deposits. Australian Society of Exploration Geophysicists Special Publication 7, Geology and Geophysics Department (Key Centre) and University of Western Australia Extension Publication 26, p 371 - 381.

Dentith, M., and Randell, M., 2003. Sandstone-type uranium deposits in South Australia and North America: A comparison of their geophysical characteristics. In Dentith M.C. (Ed.), Geophysical Signatures of South Australian Mineral Deposits. Centre for Global Metallogeny, The University of Western Australia, Publication 31, and Australian Society of Exploration Geophysicists, Special Publication 12, and Primary Industries & Resources South Australia, p 233 - 247.