Regional-residual depth estimation and edge detection characterization over the southern Kibi–Winneba belt, Ghana using aeromagnetic data

An essential procedure that facilitates the analysis and interpretation of magnetic anomalies is the use of data enhancement and filtering approaches such as edge detection and depth estimation techniques. This is because these data enhancement and filtering approaches are useful in elucidating amplitude variations within original data so that the observed magnetic anomalies can be interpreted in terms of their corresponding geologic sources. Thus, magnetic intensity responses over the southern Kibi–Winneba belt have been filtered using the Fast Fourier Transform approach to delineate shallow and deep-seated anomalies. These magnetic anomaly responses were subsequently transformed to be symmetrically aligned with their respective subsurface geologic sources using the reduction-to-pole technique. The transformed shallow and deep-seated magnetic anomaly responses were then used to facilitate the delineation of various geological structures and boundaries using edge detection techniques, comprising first vertical derivative, tilt angle derivative (TDR), 3D Euler deconvolution (ED), and the Center of Exploration Targeting (CET) grid analysis techniques. Depth estimation techniques consisting of analytic signal, source parameter imaging and the radially averaged power spectrum techniques were also used to determine the source depths of the observed magnetic anomalies. Results from the edge detection techniques outlined several NE–SW trending lineaments particularly predominant within the eastern and southern part of the study area. These predominantly trending NE–SW delineated lineaments are of much relevance to gold mineralization occurrence within the Kibi–Winneba belt. The outlook of the results obtained from the depth estimation techniques denotes comparativeness. For the regional magnetic component, the average maximum depth was 6865 m whereas an average maximum depth value of 2757.5 m was obtained for the residual (near surface) magnetic sources within the study area. The estimated depth solutions generated using the ED technique for the regional and residual magnetic intensities significantly correlated with various source edges delineated on their respective TDR maps. Also, the magnetic source depths estimated using the aforementioned depth estimation techniques corroborated with depth ranges estimated in the literature. This further indicates that the techniques employed are essential in outlining the structural framework of the study area.