Integrated Spectral Analysis and Source Parameter Imaging(SPI) of High-Resolution Aeromagnetic Data for BasementDepth Estimation in The Yola Arm, UpperBenue Trough, Nigeria

Abstract

The Yola Arm of the Upper Benue Trough in Nigeria is a geologically complex region with limited subsurface data, hindering a detailed understanding of its basement configuration and sedimentary architecture. This study employs high-resolution aeromagnetic data to estimate ‎basement depths and characterize subsurface structural variations using both spectral analysis and ‎Source Parameter Imaging (SPI). The aeromagnetic data were processed with standard corrections, ‎Reduction to the Equator (RTE), and regional-residual separation to enhance anomaly ‎interpretation. Spectral analysis of 28 overlapping blocks identified shallow magnetic sources ‎ranging from 0.10 to 0.95 km (average 0.55 km), typically associated with intrusive bodies or ‎mineralized zones, and deeper sources from 0.70 to 3.20 km (average 1.95 km), likely ‎corresponding to structural depressions and variable sediment thickness. SPI results revealed ‎depths from 160 m to over 3,400 m, highlighting significant basement heterogeneity. Depth variations are consistent with fault-controlled horst-and-graben structures, reflecting rift-related tectonics and differential sediment accumulation. Integration of the spectral and SPI methods ‎provides a reliable characterization of basement morphology, indicating basement uplifts in the ‎northwestern and central areas and deeper sub-basins in the southeastern parts‎.