Geophysical Investigation of the Precambrian Iron Ore Deposit in the Area Around Tajimi, Kogi State, North Central Nigeria

Abstract

This study involves geological and geophysical investigations aimed at delineating extent of the Precambrian iron ore deposits in the Tajimi area, Kogi State, North Central Nigeria. The research integrates field geological mapping on the scale of 1: 50,000 surveys, comprising the Vertical Electrical Sounding (VES) survey and airborne magnetic surveys to identify the iron ore and determine their lateral and vertical extents. The geological study reveals a Precambrian iron ore deposit. Geoelectrical data were interpreted to delineate resistivity anomalies indicative of iron ore mineralization, with low-resistivity zones correlating with ferruginous zones and high-resistivity layers representing overburden or non-ore-bearing Formations; while low low-resistivity layers represents the ore-bearing Lithology. The combined geologic and geophysical approach (Source Parameter Imaging, 3D Euler Deconvolution and Analytical Signal) enabled the estimation of the deposit's thickness at the edge of the iron ore deposit in contacts with the surrounding basement rocks. Magnetic Reduction to Equator and Regional-residual separation were carried out on the acquired magnetic data to centre magnetic anomaly peaks over the iron ore bodies and expunge noise backgrounds respectively. Horizontal and Vertical Derivatives (VD & HD), for delineation of lineaments of magnetic sources, subsurface structures presenting as  faults, folds and contacts or lithologic boundaries, were employed in the study as well as Source Parameter Imaging, Euler Deconvolution and 3D Magnetic Inversion techniques for determining both the lateral and depth extents of the iron ore deposits in the study environs.