Predictive mapping of the mineral potential using geophysical and remote sensing datasets in parts of Federal Capital Territory, Abuja, North- Central Nigeria

Abstract

GIS modelling is gaining wide application in providing solutions to wide ranging geoscientific problems. A knowledge based Mineral Prospectivity Mapping (MPM) using Fuzzy Logic has been adopted in this study for a regional scale mapping of mineral potential in Sheet 185 Paiko SE, North Central Nigeria. Mineral Prospectivity Mapping (MPM) is a multi-step process that ranks a promising target area for more exploration. This is achieved by integrating multiple geoscience datasets and using mathematical tools to determine spatial relationships with known mineral occurrences in a GIS environment to produce mineral prospectivity map. The study underlain by rocks belonging to the Basement Complex of Nigeria which include migmatitc gneiss and schist, granites of different compositions and textures and alluvium. The datasets used in this study include aeromagnetic, aeroradiometric, structural, satellite remote sensing and geological datasets. Published geologic map of the Sheet 185 Paiko SE was used to extract lithologic and structural information. Landsat images were used to delineate hydroxyl and ironoxide alterations and to identify linear and fault structures and prospective zones at regional scales. ASTER images were used to extract mineral indices of the OH-bearing minerals including alunite, kaolinite, muscovite and montmorillonite to separate mineralized parts of the alteration zones. Aeromagnetic data were interpreted and derivative maps of First Vertical Derivative, Tilt derivative and Analytic signal were used to map magnetic lineaments and other structural attributes while the aeroradiometric dataset was used to map hydrothermally altered zones. These processed datasets were then integrated using Fuzzy Logic modelling to produce a final mineral prospectivity map of the area. The result of the model used predicted well the known deposits and also highlighted areas where further detailed exploration may be conducted.