Application of filters in the mapping of potential gold-bearing structures using magnetic and radiometric data

This inclusive innovation study aimed to generate a high-resolution metallogenic potential map of the mineral-rich Oban Massif in southeastern Nigeria by integrating structural, lithological, and hydrothermal alteration indicators from airborne geophysical data. A comprehensive suite of high-resolution airborne magnetic and radiometric data was processed. The total magnetic intensity data (TMI) as well as grids of first and second vertical derivatives (FVD, SVD), analytic signal (ASIG), tilt angle derivative (TAD), and total horizontal derivative (THD) were subjected to the Centre for Exploration Targeting (CET) procedure to elucidate the subsurface architecture. The analysis revealed a polyphase deformation history dominated by a NE-SW structural trend, which provides critical migration pathways for mineralizing fluids. A direct spatial correlation was established between elevated magnetic intensities and anomalous potassium concentrations, delineating a prospective zone for igneous-related gold mineralization. Lithological diversity, including shales, hornfels, gneiss, schist, and granitoids, was identified. Radiometric K/Th ratios ranging from -0.5 to 1.5 %/ppm were recorded, with specific anomalous zones (exceeding the background range of 0.16-1 %/ppm) signaling potential for gold-silver, polymetallic, molybdenum, tungsten, and rare earth element deposits. Depth estimates from source parameter imaging (SPI), standard Euler deconvolution (SED), and 2-D forward modeling indicate sediment thicknesses extending to approximately 2580 m. The outcome is a new, targeted framework that moves beyond regional assessment to define specific exploration targets, thereby providing a direct tool for identifying prospective mineralization hosts within the Oban Massif.

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