EXPLORATION FOR FERROUS METALS USING GEOCHEMICAL SOIL SURVEY IN DAGBALAA TTE DISTRICT, SOUTHWESTERN NIGERIA

Abstract: Geochemical survey of residual soils to explore for ferrous metals in the more prospective Dagbala-Atte District of Igarra Schist Belt, South western Nigeria was undertaken. The study involved sampling of residual soils from 49 sites; geochemical analysis of the soil samples for 9 elements, namely, Co, Cr, Fe, Mn, Mo, Ni, Ti, V and W; and subjecting the geochemical analytical data to both qualitative and statistical analyses which include univariate (histograms and box plots), multivariate statistics (correlation matrix and factor analysis) and construction of geochemical distribution maps. By determining the threshold for each element using the univariate plots, it was possible to isolate elements having anomalous values which were compared with their background concentrations in the World's soils. As a result, only four of the ferrous metals subjected to statistical studies, viz, Co, Cr, Ni and V, were found to have significant anomalous values and are suspected to be mineralized in the district. On the basis of correlation matrix and factor analysis, three groups of element association were recognized, viz, Cr-Ni-V-Ti-Fe, Mn-Co-Ni and Mo-Fe-V groups. Only one suspected mineralization, viz, Cr-Ni-V mineralization and a Co-Ni anomaly were inferred to be present in the Dagbala-Atte District. With the aid of the elemental geochemical distribution maps the suspected Cr-Ni-V mineralization was linked to the sheared, silicified rock at the northern and southern parts of the district while the suspected Co-Ni anomaly is linked to the quartz-biotite schist at the southwestern part. Based on the foregoing findings, it is recommended that lithogeochemical survey be carried out in the areas circumscribed for the suspected mineralization and anomaly of Cr, Ni, V and Co in the district.

Keywords: Box plots, Factor analysis, Geochemical distribution map, Mineralization