High-resolution airborne magnetic detection of iron ore deposits

Abstract

The iron and steel industry has been called the "backbone" of industrialisation and the "bedrock" of national economies. For almost 50 years, Nigeria has endeavoured to construct a publicly sponsored iron and steel sector in Kogi State, Nigeria's iron ore hub, to expedite the nation's economic development. However, amongst the most significant geoscientific barriers hindering this endeavour are the unpredictability of local materials, notably iron ores, and the rugged topographical challenge of exploring more materials. As a part of the process of abating this challenge, a high-resolution airborne magnetic survey was conducted by the Nigerian Geological Survey Agency. This study aims to delineate the spatial occurrences of the iron ore resources in Kogi State using the recently acquired high-resolution airborne magnetic datasets. The Centre for Exploration Targeting (CET) grid analysis, analytic signal, and Euler deconvolution analytical technique were employed to aid the interpretation, and the known iron ore mines were used as control. The total magnetic intensity and residual map did not reveal the potential ore deposits by mere qualitative interpretation. The lineament density map displays a very poor consistency with the known iron ore deposits due to the geostructural complexity of the study area. However, the high-amplitude peaks of the analytic signal map are consistent, perfectly correlate with all the known existing mines, and reveal potential iron ore deposits. These peaks are in the range of 0.147 to 0.430 nT/m. The Euler deconvolution reveals the depth of potential deposits to be <250 m, while the analytic signal reveals a depth range of 49.594 to 150.926 m. Compared with previous related studies, shallower depth estimates and relatively higher amplitude peaks from the analytic signal were observed. These were attributed to this study's higher resolution acquisition parameters. Finally, we recommend that stakeholders and policymakers prioritize the high-amplitude peaks of the analytic signal as target zones for further iron ore exploration and exploitation processes.