GEOLOGICAL CHARACTERIZATIONS AND DEPTH TO BASEMENT MAPPING OF MAGNETIC SOURCES USING HIGH-RESOLUTION AEROMAGNETIC DATA: A CASE STUDY OF ADO EKITI AND ITS ENVIRONS, SOUTH-WEST NIGERIA

The impacts of the magnetic investigations play a vital role in mapping geological, mineralogical, and structural features, especially in basement complex terrains. Despite Ado Ekiti’s rich crystalline rocks and resource potentials, limited detailed studies hinder effective exploration and planning. This study uses aeromagnetic data (sheet 244), acquired from the Nigerian Geological Survey Agency (NGSA) via Fugro Airborne Survey, to delineate subsurface structures, estimate magnetic source depths, and identify basement trends. Aeromagnetic data were processed and interpreted using Excel and Geosoft Oasis Montaj (v8.4) to model subsurface basement topography. Techniques applied included Gaussian filtering, Total Magnetic Intensity (TMI), Reduction to Pole (RTE), Analytical Signal (AS), First-Order and Second-Order Vertical and Horizontal derivatives, Tilt Angled Derivatives (TAD) and their corresponding maps were utilized for the qualitative analyses, while Radially Power Spectrum (RAPS), Source Parameter Imaging (SPI), 3D-Euler Deconvolution (3D-ED), and their corresponding outputs were also utilized as quantitative measure for causative bodies depth estimation and structural evaluation. The study revealed TMI values ranging from -977 to 428 nT, classified into high, moderate, and low amplitudes. AS revealed values range of 0.3 to 5.0nT, 0.07035 to 0.1912nT and 0.000 to 0.0609nT respectively classified as high, moderate and low magnetic intensities. RTE amplitudes ranged from 54 to 653 nT. FVD ranged in amplitude from -3.6233 to 4.7096nT and were vertically aligned along the N-S trend. FHD along x axis ranged from 2.1415 to 1.8982nT trending along E-W and NW-SE direction and in Y-axis NW-SE. TAD ranged from -1.57 to 1.54 nT. SPI estimated depths of 96–111 m (shallow) and 335–420 m (deep), 3D-ED revealed depths from 132.2 m to 2233.9 m. The modeled maps (AS, TAD, and 3D-ED) revealed the basement structure and magnetic source depths in Ado Ekiti. Key subsurface features, including faults, contacts, and boundaries, trend NE-SW, NW-SE, and E-W, aligning with Pan-African and Liberian Orogenies. The Depth estimation is an indication that both the highlighted shallow and deep sources are good potential for mineral exploration, groundwater development, and engineering applications.