STRUCTURAL ANALYSIS OF HIGH-RESOLUTION AIRBORNE MAGNETIC DATA OVER ILORIN AND ITS ENVIRONS, NIGERIA

Abstract

ABSTRACT The use of derivative filtering, analytic signal transformation, Euler deconvolution, and upward continuation in magnetic data analysis has gained significant attention in geophysical studies, especially for subsurface structural mapping. Ilorin and its environs, the study area, are part of the Nigerian Basement Complex known for complex tectonic deformation. Different geophysical approaches have been applied in the past for interpreting airborne magnetic data in the region, but integrated multi-filter techniques remain less explored. The objectives of this work are to (i) To Identify subsurface structural features. (ii) Analyzing magnetic anomalies to infer geological structures and tectonic settings. (iii) Evaluate the depth, orientation, and geometry of magnetic sources. (iv) Map lineaments and structural intersections relevant to mineral exploration and groundwater targeting. The main datasets used include high-resolution total magnetic intensity grids and geological base maps obtained from the Nigerian Geological Survey Agency. In this study, first vertical derivative (FVD), total horizontal gradient (THG), tilt derivative (TDR), and analytic signal (AS) filters were applied, while Euler deconvolution was used to estimate depth solutions and structural indices. Upward continuation was conducted at 500 m, 1000 m, 1500 m, and 2000 m to separate shallow and deep magnetic contributions. The results revealed prominent NE–SW trending faults, shear zones, basement highs, and depressions consistent with Pan-African structural trends. Lineament and skeleton vector maps showed dense networks of intersecting structures, while upward continuation confirmed persistent deep crustal anomalies. The analytic signal delineated magnetic source boundaries, and Euler solutions highlighted deeply rooted intrusive bodies and fault blocks. This study demonstrates that integrated derivative filtering and depth estimation techniques are effective tools for mapping tectonic complexity and guiding exploration strategies within Ilorin and its environs.