Measurement of radioelement contents of rocks of UGEP, S.E. Nigeria, by gamma-ray spectrometric and instrumental neutron activation analysis techniques

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).