Comparative analysis of Airborne and Terrestrial survey of Odeda Lithology, Ogun State, Nigeria, using Radiometric approach

Abstract

Airborne radiometric survey (ARS) is now been used to compliment the terrestrial radiometric survey (TRS) due to the wider coverage capability with highly sensitive automated radiometric survey meter. In this study, ARS and TRS were carried out to examine the radiometric behaviour of weathered basement in Ogun state for uranium, thorium, potassium alongside their total count. ARS radiometric data was collected from the radiometric department of Nigerian Geological Survey Agency, Abuja, Nigeria, in line with the sampling point coordinate of TRS. The TRS was done by collecting soil samples randomly across the weathered basement area and transferred to Institute of radiation protection center laboratory, University of Ibadan, for radiometric analysis. For comparison, the two surveys were subjected to regression analysis, normalisation test, homogeneity test and geochemical superposition.The regression analysis was used to generate the empirical model connecting the two surveys for each radiometric components. The degree of fitness, coefficient of correlation and spatial distribution of the two surveys were as well computed and constructed. The result obtained showed more elevated concentrations of uranium and thorium in ARS compared to TRS. The total count accounted for thorium as its major prevalence radioelememt constituent. The spatial distribution of uranium showed a reflection of high similarity index in both the ARS and TRS with elevated response around pegmatite unit. The homogeneity test revealed high coefficient of variation values (CV > 50 % ) in the radioelements which implies that the radioelements are not from a single sources. The regression models developed for ARS and TRS accounted for good correlation coefficient of 81 %, 71 % , 76 % and 71 % for uranium, thorium, potassium and total count, respectively. This study has, therefore, proven the two radiometric survey methods to be comparable and efficient in delineating the radiometric anomaly associated with the study area.