Pedogeochemical survey for uranium mineralization in parts of Igarra Schist belt, Southwestern Nigeria

Abstract

Pedogeochemical survey for uranium mineralization in Dagbala-Atte district, Igarra schist belt, southwestern Nigeria was carried out. The concentrations of As, Au, Fe, Mn, Mo, Ni, Pb, Se, U and V in the residual soils were subjected to univariate and multivariate analyses and plotted on geochemical distribution maps to delineate possible U-mineralization areas. Histograms and box plots showed the elements are log-normally distributed with threshold values of 9.47 %, 10.8, 1589, 2.98, 45.6, 31.0, 0.68, 8.59, 122 ppm and 10.6 ppb, respectively for Fe, As, Mn, Mo, Ni, Pb, Se, U, V and Au. Correlation matrix revealed a strong correlation between U and each of Fe, Mo and Pb indicating close primary association among these four elements. Factor analysis revealed association of U, Mo and Pb implying possible occurrence of U in the granitic rocks of the area. Geochemical maps showed that the strongest U anomaly occurred in the northeastern part of the district that is underlain by granitic gneisses with numerous unmapable granite-pegmatite veins, which possibly are the host of the U mineralization. Copious geological study of these granite-pegmatite veins is recommended.

Keywords: Anomaly, box plots, correlation matrix, geochemical distribution map, uranium mineralization.