Aeromagnetic Lineament Analysis for Structural Control on Mineralisation in Edo State

This study analyses aeromagnetic lineaments to characterise structural controls on solid mineral occurrences in Edo State, South South Nigeria. Edo State's basement complex hosts diverse mineral resources including marble, granite, quartzite, tantalite, and limestone, but the relationship between structural lineaments and mineral distribution has not been quantified from aeromagnetic data analysis. This study processes NGSA aeromagnetic data for the Okpella, Igarra, and Auchi map sheets at 1:100,000 scale. Processing includes IGRF removal, reduction to the pole, and computation of total horizontal derivative and analytic signal amplitude. Automated lineament extraction using the Hough transform is applied to the first vertical derivative image, supplemented by manual digitisation to capture features missed by the automated algorithm. Lineament density and orientation statistics are computed in ArcGIS using a moving window analysis. Spatial correlation between lineament density and mineral occurrence locations from the NGSA mineral occurrence database is quantified using point pattern analysis. Findings reveal a dominant northeast-trending lineament set at azimuths between 45 and 65 degrees, with a secondary northwest-trending conjugate set. Marble and limestone occurrences show the strongest spatial correlation with northeast-trending lineaments, with 76 percent of sampled occurrences within 1 kilometre of a major lineament. Areas of highest lineament intersection density coincide with known marble quarrying sites in the Igarra belt. Two areas of anomalous lineament density in the Auchi district without documented mineral occurrences are identified as priority ground investigation targets. The study provides a structural framework for mineral exploration targeting in Edo State.

Keywords: aeromagnetic lineaments, structural control, mineral exploration, Edo State, lineament density.