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High resolution airborne magnetic and radiometric data were used to map probable sites for polymetallic-magmatic hydrothermal deposits in the study area. The first and second vertical derivatives, horizontal gradient, analytic signal and tilt angle derivative were used to enhance magnetic data in order to determine the location of short wavelength anomalies, magnetic sources and geologic boundaries. Also, to understand and detect radiometric anomalies controlling mineralization in host rocks, enhancement operations involving potassium (K), equivalent thorium (Th), equivalent uranium (U) concentrations and ternary imageries were carried out. All these operations enabled the delineation of responses associated with mineralization, lithology and geologic structures. Generally, lineaments trend in the NE-SW, NNE-SSW, NW-SE and E-W directions, and serve as potential pathway for hydrothermal fluid migration and mineralization. Radiometric anomalies from spectrometric imageries are caused by felsic minerals, hydrothermal rock alterations, widespread shales, residual clay, oxides and accessory minerals that constitute regolith of the area. The coincident high magnetic and potassium intensities sites in Anambra Bain (AB), Abakaliki Anticlinorium (AA), Ikom-Mamfe Rift (IMR) and Obudu Plateau (OP) are probable sites for polymetallic-magmatic hydrothermal deposits. Generally, the joint magnetic and radiometric results were able to establish link between lithology, geologic structures and hydrothermal alteration patterns.

High resolution airborne magnetic data acquired between 2005 and 2010 were used to determine depth to shallow and deep magnetic sources in some parts of Southeastern Nigeria. Various depth estimation methods such as standard Euler deconvolution (SED), source parameter imaging (SPI), spectral depth analysis (SDA) and two dimensional (2-D) forward modeling were applied. Results obtained from SED, SPI and models of profiles 1 and 2 indicate that the Abakaliki Anticlinorium (AA) and Ikom-Mamfe Rift (IMR) regions are dominated by short wavelength magnetic anomalies caused by extensive tectonic events. The SED map showed depth to shallow and deep magnetic sources ranging from ~ 16.6 to ~ 338.3 m and ~ 394.3 to ~ 5748.1 m respectively. Likewise, depth estimates from the SPI map varies from ~ 147.1 to ~ 554.2 m (shallow magnetic sources) and ~ 644.2 to ~ 6141.6 m (deep magnetic sources). The result obtained from SDA revealed depths to deep magnetic basement in the range of ~ 769 to ~ 6666 m with an average of ~ 3449 m. Also, it showed that depth to shallow magnetic sources vary between ~ 119 and ~ 434 m with mean of ~ 269 m. The 2-D forward modelling showed maximum depth values of ~ 4700, ~4600 and ~ 6500 m in the models of profiles 1, 2 and 3 within the Anambra Basin (AB), Afikpo Syncline (AS) and Calabar Flank (CF) respectively. Generally, from all the various methods applied the results indicate that AB, AS and CF are dominated by long wavelength anomalies. The 2-D models indicated that the basement framework is undulant. Also, depth estimates involving the various methods used in this study correlate strongly with each other in the AB, AS and CF geological regions.