A combination of gamma-ray spectrometry and instrumental neutron
activation analysis is adopted in the quantitative evaluation of the
three major radioelements (U, Th and K) concentrations in some rock
samples collected at previously delineated radiometric anomalies
(Geological Survey of Nigeria, 1976), in the Ugep area of the Lower
Benue Region of Nigeria. A preferential enrichment of Th to U and K is
observed in most samples analysed, with UTh ratios ranging from 0.11 to 0.25.
K contents are fairly normal in some samples analysed, with Th (ppm)/K (%) ratios ranging from 2 to 5. Anomalous ThK ratios, Th (ppm)/K (%) ratios ranging from 2 to 5 up to 16, were
obtained for samples from those areas identified in the airborne survey
maps as “Th—anomaly zones” (Geological Survey of Nigeria, 1976).