Application of Electronic Personal Dosimeter in Thermo-Luminescence and Isotopic Ratio Dating of Limestone Using Uranium Series

Abstract

Application of e lectronic personal dosimeter in Thermo-Luminescence and isotopic ratio dating of limestone using uranium series has been examined in the dating of prehistoric activities in Gaborone area of Mogoditshane-Tsolamosese (Block 4) Botswana. isotopic ratio of the stable 206Pb to the parent nuclide 238U, was valuable to this research as it enabled the isotopic ratio technique to be applied for the study with better precision and accuracy. The aim of this research was to investigate the age of limestone existence by Thermo-Luminescence (TL) and isotopic ratio dating of limestone using uranium series measured by electronic personal dosimeter (EPD). This was achieved by quantifying the limestone sediments used in Gaborone at different topographic locations as affected by natural and human activities, and thus determining the effectiveness of Thermo-Luminescence and isotopic ratio methods on dating of limestone. From both Thermo-Luminescence and isotopic ratio methods, varying results were obtained with average limestone ages of 26 MY and 16 MY respectively for the Gaborone area of Mogoditshane-Tsolamosese. The results of this work revealed that the isotopic ratio technique is more reliable than EPD-TL for limestone dating, and thus the 207Pb/2°6Pb inverse Concordia plot from [so plot gave a weighted mean age of the samples as 4308 + 1900/-770 MY, with an MSWD of0.51.