Mapping of Orogenic Gold Mineralization Potential in the Kushaka Schist Belt, Northcentral Nigeria: Insights from Point Pattern, Kernel Density, Staged-Factor, and Fuzzy AHP Modeling Techniques

The Kushaka greenschist belt is one of Nigeria's known gold mineralized belts. This study used geological information from geophysical, remote sensing, surface geology, and geochemical interpretations to produce a gold mineral potential map (GMPM) in the belt. Statistical methods that involve fractal, Fry, Poisson distribution, statistical distance distribution, cross-correlation, similarity coefficient, and univariate and bivariate kernel density estimation techniques were used to establish spatial relationships between gold expressions and geological structures. Using an orthogonal varimax matrix, this study evaluated ore-related elements associated with orogenic gold mineralization through staged-factor analysis (SFA). Critical factors such as “gold/ligand source”, “heat source”, hydrothermal alteration subsystem, geologic structures, and gold enrichment were integrated using a mineral system approach and fuzzy AHP modeling technique to produce GMPM for the study area. The statistical analyses showed that NNE–SSW and NE–SW trending geologic structures primarily control orogenic gold mineralization in the belt. SFA revealed that gold minerals are associated with rare earth elements (lithium, zircon, tin, scandium, and yttrium), manganese, and sulfide minerals (lead–zinc). Areas with high mineralization potential scores are found in faulted and hydrothermally altered metasedimentary and granite rocks. The GMPM model's accuracy using the prediction-area (P–A) rate curve and 31 known gold occurrences resulted in an 85% success rate. This study concluded that magmatic-metamorphic processes and tectonic deformation events primarily influence orogenic gold mineralization in the Kushaka schist belt, and in some other Nigeria’s schist belts. The methodology adopted in this study can be applied to other geological settings with similar characteristics to delineate orogenic gold mineralization potential zones.