Correlations between airborne and terrestrial gamma-ray spectrometric data in the bitumen deposit area, Ogun State, Nigeria

Abstract

Radioelements deposit (uranium, thorium and potassium) were found to be influenced by geological bedrock compositions and their response varies from place to place. In this study, two radiometric surveys (ground and airborne) were carried out to investigate the possible relationship in the response of radioelements deposit to the geological composition of a bitumen rich area in Ogun State, Nigeria. Regression analysis was adopted to establish the empirical mathematical relation that exists between the two surveys. With this, the correlation between the two surveys was deduced and interpreted in conjunction with the geological map of the study area. Coefficient of variation was also utilized to assess the level of homogeneity of the surveys carried out. A linear empirical mathematical model was established for the two surveys. The results revealed the coefficient of correlation (r) of 0.66407, 0.70398 and 0.68792 for thorium, uranium and potassium respectively. The p-values obtained at 95% confidence level for the three radioelements also indicated that there exists a significant relationship (p-value < 0.05) in the two surveys carried out. The results obtained for uranium and potassium for the two surveys were found to be comparable while slight disparity exists in that of thorium. The disparity was attributed to environmental factors such as temperature, precipitation and soil moisture. Contour plot was used to depict the radioelements distribution across the study area. Uranium and thorium were found to be highly enhanced and formed the major dominance in the study area. The study shows that the responses of radioelement from the two surveys are statistically correlated and comparable irrespective of the geological composition and the time at which they were carried out. Keywords: Model, Regression, Bitumen, Radioelement, Empirical