In order to assess the application of ESR to dating of authigenic chemical precipitates (including gypsum, phosphate and calcrete deposits), a wide variety of samples of different age, purity, mineralogy and geographical distribution were utilized. Observations of a number of radiation-induced signals indicate that the accumulated dose (AD) derived from individual signals may vary by one or two orders of magnitude. Thus the selection of an "appropriate" signal of the ESR spectrum is critically important in ESR dating. For this reason, the first stage of our investigation involved the irradiation of selected samples by a 60Co γ-ray source, with a known absorbed dose (100 or 400 Gy), to check the reliability of AD values obtained from the routine method. The results enable us to select a suitable signal for dating. A comparison of ESR and 14C ages of duplicate pedogenic calcrete from late Pleistocene sediment indicates that a valid method for the assessments of annual dose rate is of paramount importance. Based on our current experience, ESR appears to be a feasible technique for dating chemical precipitates such as gypsum, phosphate and calcrete deposits.
|Number of pages||8|
|Journal||International Journal of Radiation Applications and Instrumentation. Part|
|Publication status||Published - 1989|