Geological structure and hydrothermal alteration mapping for mineral deposit prospectivity using airborne geomagnetic and multispectral data in Zuru Province, northwestern Nigeria

Abstract

Spatial associations involving alterations and structures are common with orogenic systems, however porphyry deposits are not spatially well defined especially due to overprinting of alteration types. In this study, multi-disciplinary geoscience information from digitally-enhanced airborne data over Zuru province, northwest Nigeria were analyzed and synthesized to unravel uncertainties about the spatial alignment of both structural and hydrothermal features in porphyry prospects. Processed aeromagnetic data showed the tectonic regime and the associated lineaments of the Anka province which presumably controlled the mineral localization and distribution in the province. The multispectral interpretations of the hydrothermal expressions illustrated the major alteration zones such as potassic, phyllic, argillic and propylitic domains. The delineated surface structures in the province are regarded as the main reason for alteration zone formation in the country rocks where the traversed lineaments in the existing rocks symbolizes a plumbing system responsible for hydrothermal fluid flow, and hence mineral bearing alteration zones were developed. Spatial analysis involving contrast estimation was performed to quantify the spatial relationship between known mineral deposits and geologic features that can influence mineralization. Propylitic alterations are noticeable as prominent alteration zones with mineral deposits, whereas the phyllic alterations presented the lowest possibility of mineral occurrence. Further spatial analysis involving statistical contrast estimation between mineral deposits and a deep-seated regional structure showed maximum spatial relationship around the 35-km buffer zone. The mineral deposits exhibit spatial association with the trans-current lineament assertive of a strong influence of the geologic structure on mineral deposition and regional pluton emplacement.