AUTORADIOGRAPHIC STUDY OF URANIUM AND THORIUM IN FOSSIL BONES

The relation connecting the concentration of uranium (U) and thorium (Th) atoms in geological samples with alpha track production rates in the plastic track detector, LR-115 type 2, has been used for the analysis of fossil bones collected from the Siwalik Himalayas of India. U and Th distributions in radioactive fossil bones have been studied by taking alpha-particle track and fission track autoradiographs. Autoradiographs of the molar teeth of Stegodon and the rib of Elephas reveal that the enrichment of U is confined to the iron-rich zone of both samples. The results of U concentration measurements by alpha-autoradiography are distinctly lower than those obtained by fission track analysis and indicate the presence of radioactive disequilibrium in fossil bones.