DISEQUILIBRIUM IN THE U-238 SERIES IN SAMPLES FROM YEELIRRIE, WESTERN AUSTRALIA

Uranium-series disequilibrium studies carried out on samples from the Yeelirrie uranium deposit, Western Australia, indicate that uranium and radium have been migrating within the deposit during recent times, and are actually being removed from the deposit. Samples collected for 230Th/234U age dating were found to be substantially out of equilibrium, with 230Th/234U activity ratios ranging from 0.750 to 1.345. This can be explained by a dynamic hydrologic system in which there has been, and continues to be, uranium migration caused by leaching in this arid, oxidizing environment, and a fluctuating water table. Recent, extensive 226Ra migration (226Ra/230Th activity ratios range from 0.53 to 1.30), and a very low emanation factor (E) of 222Rn limit the quantitative application of radon exploration techniques in this environment. © 1979.