Development of a Novel Magnetotelluric Data Acquisition and Inversion Methodology for Imaging Deep Crustal Conductors Under the Nigerian Precambrian Basement Complex

The detection and characterisation of deep crustal conductors beneath the Nigerian Precambrian Basement Complex is impeded by the absence of a nationally developed acquisition strategy that accounts for the unique electromagnetic noise environment of sub-Saharan Africa, including powerline harmonics, atmospheric discharge patterns, and cultural noise from informal settlements that degrade conventional MT data quality. This research develops a novel MT data acquisition protocol and noise-adaptive inversion methodology specifically designed for the Nigerian basement complex environment. New broadband electromagnetic field recordings acquired at 25 stations across four basement provinces in Kogi, Niger, Kwara, and Plateau states form the primary dataset. The acquisition protocol incorporates remote reference stations optimised for the Nigerian diurnal noise pattern, and a new cultural noise rejection algorithm is developed that outperforms standard robust processing in synthetic benchmarks. Three-dimensional inversion of the processed MT data using a conjugate gradient inversion code produces resistivity models revealing a mid-crustal conductor at 15 to 25 kilometres depth, interpreted as a partially molten or graphite-bearing zone associated with the Neoproterozoic collision suture of the Trans-Saharan Belt. The conductor geometry and resistivity (less than 10 ohm-metres) are inconsistent with any previously published crustal model for this region. The theoretical implications for crustal rheology, seismicity potential, and mineral system controls are developed through comparison with analogous crustal conductors globally. Keywords: magnetotelluric, deep crustal conductor, basement complex, inversion methodology, Trans-Saharan Belt