ENVIRONMENTAL DOSE-RATES AND RADIOACTIVE DISEQUILIBRIUM FROM SOME AUSTRALIAN LUMINESCENCE DATING SITES

Determination of geological/archaeological ages by luminescence dating requires the measurement of the rate of delivery of radiation dose fr om the sample and its environment. For all age determinations it is ne cessary to assess whether the dose-rate has been constant during the t ime that the dose has been accumulating, and to make allowance for it if it was not. We report here results from a number of Australian site s to illustrate the information that can be found about element concen trations, about their distribution and about dose rates. Tests for rad ioactive disequilibrium form part of these measurements. Such tests ta ke the form of comparison of independent measurements of dose-rates an d/or individual elements. In general, there is little or no evidence f or disequilibrium in aeolian dune systems, even when the age of the sy stem exceeds 500 ka. However, disequilibrium has been found in several sites subject to wet conditions.