research program 2
mineral exploration in areas of cover
Reactive Uranium anomalies in waters of the Western Australian Wheatbelt
Project Leader : David Gray, CSIRO Exploration and Mining
Start date and duration: January 1, 2006 – Dec 30, 2007
Participants : CSIRO Land and Water and CSIRO Exploration and Mining
Brief project description :
In 2005 a study was initiated to examine management options for acid, saline waters in the Western Australian Wheatbelt in a joint study between the Department of Environment, the Department of Agriculture and CSIRO. A serendipitous outcome of the first year of study of acid, saline waters in the Western Australian Wheatbelt has been the discovery of anomalous uranium (U) concentrations (up to ca. 900ppb) in an widely dispersed suite of groundwaters, artificial drains and surface drainages.
Water geochemistry (groundwaters and/or artificial drain or surface-waters) can be a useful tool for the exploration of U ore deposits as a water sample integrates information over a large area and thus reduces the amount of samples required to identify potential U-rich areas. A high U concentration in waters does not, however, necessarily mean the presence of economic mineralization. In order to determine if a U-rich sample is prospective,, one can use U-series isotopes. For instance, it has observed that in an arid environment waters from economic uranium deposits are characterized by 234 U/ 238 U activity ratios near or at equilibrium (~ 1), whereas waters from non-economic deposits exhibit high 234 U/ 238 U ratios (> 2). Preliminary results on a subset of waters from this study show that not only they have a high concentrations in U (up to ca. 900 ug/L) but also 234 U/ 238 U near equilibrium (1.13-1.43), much lower than 234 U/ 238 U waters generally measured in arid environments (e.g. ~ 2 in South Africa). In addition, measured 234 U/ 238 U activity ratios in the U ore deposits of Yeelirrie , WA , are similar to those measured in the waters (1.12-1.37) in this study. Assuming that U mineralization is dissolved congruently, one can expect the same 234 U/ 238 U in the water and the U deposits leached. Thus, these preliminary results are consistent, but not a confirmation of, the presence of U mineralization of economic significance.
On the basis of the anomalies that have been identified in the first year of the study, a second year of confirmation and in-fill sampling around existing anomalies is proposed. In addition, further U-Th series isotope analyses will be undertaken to assess the utility of this technique to define potential areas of U mineralization. Consistent with the stated aims of CRC LEME a commercial partner, Mindax Limited has been engaged over the next two years to assist in the sampling and exploration activities. Contingent with the results of the confirmation and in-fill sampling, the program will develop to include such areas as regolith geology, mineralogy, geophysical investigations (radiometrics and magnetics) and reconnaissance drilling of prospective sites.
Deliverables (outputs) and expected impacts of research (outcomes):
- Identification of anomalous areas for dissolved Uranium in, and possibly adjacent to the Western Australian Wheatbelt.
- Identification of geochemical and isotopic techniques for Uranium exploration in these environments.
- Increased efficiency of ore discovery within WA.
- Commercial benefits through the licensing of such technology and the increased call on the regolith geochemistry expertise resident in WA from both national and international clients.