Exploration of iron ore deposits in parts of Kogi State, northcentral Nigeria: Analyses from airborne magnetic and ASTER datasets

Abstract

Kogi State is known for its iron ore deposits, and Kakanda township is one of those places that possess iron ore deposits. However, little information about the extent and locations of possible iron ore mineralized zones is available due to limited research in that area. Hence, this study utilized aeromagnetic and Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) datasets for the delineation of ironstone and banded iron deposits comprising magnetite and hematite in Kakanda and its environs in Kogi State, northcentral Nigeria. Enhancement techniques such as residual magnetic amplitude and analytic signal amplitude carried out on the aeromagnetic data revealed the concentration of iron ore deposits, especially in the southern, eastern and western parts of the study area. This finding is consistent with signatures derived from other data enhancement techniques involving the total horizontal derivative, tilt derivative and 3D Euler deconvolution techniques, which are principally used to map structures guiding mineralization in the study area. Furthermore, analyses of the ASTER dataset using true and false color composites and combinations of band ratios indicate the occurrence of iron oxide and clay alterations related to iron ore mineralization in the study area. The signatures related to iron ore mineralization in the aeromagnetic data and ASTER dataset are consistent with each other. The overlap of these signatures was used to produce the iron ore prospectivity map of the study area. The study showed that areas of delineated lineament coincide with areas of iron ore mineralization. In the same vein, areas of dense lineaments coincide with areas of iron ore mineralization, especially in the southern and eastern parts of the study area. Therefore, the mineralization in the study area is structurally controlled. The iron ore prospectivity map produced will serve as reference for mineral explorationists in the area to engage in targeted exploration, rather than random exploration and exploitation especially in developing countries which impacts the environment negatively. Hence, further exploration activities involving electrical resistivity and gravity surveys and geochemical studies should focus on areas where there is an evident overlap of lineament and signatures reflecting iron ore mineralization in the study area.