Some applications of uranium tracing in geological samples using thermal neutron induced fission

Abstract

The mode of distribution of uranium in geological samples is closely related to the type of geochemical environment during the time of formation or alteration of a specific specimen. By high resolution micromapping of U in sediment samples from the Kaapvaal Craton, South Africa, using n-induced U-235 fission tracks in mica detectors, information is obtained about the redox potential of the hydrosphere- atmosphere system at the time of U-deposition or remobilization. Mineralogical and textural considerations as well as radioactive disequilibria in the natural U-decay series, measured by α-spectrometry, were used to identify the type of U-mobilization. The U-distribution patterns of carefully selected conglomerate samples from the Witwatersrand basin are in agreement with the assumption of a predominantly reducing Earth atmosphere at the time of basin formation some 2.6 × 10 9 y ago.