地理情報学と地球統計学: 概要

Statistical Dissection of Lithogeochemical Data from Parts of the Igarra Schist Belt, Southwestern Nigeria

Mohammed Adepoju

Statistical analysis of the lithogeochemical data from parts of igarra schist belt was carried out with a view to testing the rocks for their mineralization potential. Univariate and multivariate statistical analyses of dispersion box plot and factor analysis, respectively, were employed on the concentrations of Ag, As, Au, Bi, Cu, Mo, Pb, Th, U and Zn in 45 rock samples. The dispersion box plots showed that the trace elements are log-normally distributed in these rocks and granted the threshold values for the elements but Zn as 240 and 5.2 ppb for Ag and Au, along with 3.1, 0.93, 77.63, 2.22, 18.68, 21, and 2.2 ppm for As, Bi, Cu, Mo, Pb, Th, and U, respectively. Factor analysis gave four models as Mo-Cu-ThBi-Ag; U; Zn-Th; and as factors. The interpretation of these data suspected two types of mineralization and also inferred two types. The two suspected mineralization include Aubearing marble and Ag-Cu bearing silicified sheared rock both along the shear zone in the district; while the two inferred mineralization are U mineralization in the pegmatite veins and Pb-Zn mineralization in the metaconglomerate.