Theoretical Development of Multiscale Potential Field Processing for Deep Mineral Exploration in Nigerian Basement Terrain

This study develops original multiscale processing methodologies for potential field (gravity and magnetic) data to improve the characterisation of deep mineralisation targets in Nigerian basement complex terrain, making a fundamental methodological contribution to exploration geophysics. Conventional potential field enhancement operators applied at a single scale are adequate for near-surface structural mapping but inadequate for separating signals from deeply buried mineral bodies from the complex superposition of near-surface responses, instrument noise, and regional trends. Multiscale analysis using wavelet transforms provides a mathematically rigorous framework for scale-dependent signal decomposition that can selectively enhance deep source anomalies. This study develops novel continuous wavelet transform-based and discrete wavelet packet processing methods specifically designed for the mixed-scale signal characteristics of Nigerian basement complex potential field data. Theoretical analysis establishes the depth selectivity, noise sensitivity, and resolution characteristics of the new operators. Synthetic benchmark datasets representing Nigerian geological scenarios are used for method validation. The methods are applied to NGSA aeromagnetic and ground gravity data for a 12,500-square-kilometre test area in Niger, Kwara, and Kogi States. Comparative analysis against conventional processing methods (THD, tilt angle, Euler deconvolution) benchmarks performance. Findings demonstrate that the wavelet-based operators achieve 28 percent improvement in depth estimation accuracy for synthetic targets at 200 to 500 metres depth, where conventional methods show significant overestimation bias. Application to the field data identifies 12 anomalies with depth characteristics consistent with deeply-buried BIF iron ore or massive sulphide targets in the 150 to 600 metre range that conventional processing does not detect. The study contributes a theoretically grounded, practically validated multiscale processing framework for Nigerian exploration geophysics.

Keywords: multiscale potential field, wavelet processing, deep mineral exploration, Nigerian basement, theoretical development.