Exploration for iron ore in Agbado-Okudu, Kogi State, Nigeria
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Date
2017-12-31
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Publisher
Arabian Journal of Geosciences
Abstract
This report details the result of geophysical exploration for iron ore; which involved vertical magnetic intensity (ΔZ)
and gravity measurements, to delineate the geometry and depth
extent of the deposit and acquiring quantitative and qualitative
information for pre-drilling purposes in Agbado-Okudu. It is
located about 3 km from Jakura along Lokoja-Jakura marble
quarry and within low latitude precambrian basement complex
district of Kogi State, Nigeria. A total of 517 magnetic measurement points along 16 traverses and 330 gravity reading along 11
profiles on the deposit in northeast–southwest azimuth were undertaken. The magnetic and gravity data enhancement involved
linear regression curve fitting and fast Fourier transform, which
were used to construct residual magnetic (RM) and gravity (RG)
anomalies, analytic signal amplitude, Euler deconvolution at
varying spectralindices (SI), power spectrum, and source parameter image (SPI), using the submenu of Geosoft Oasis Montaj
software. Interpretation of the RM and RG anomalies revealed a
primary causative body which perfectly correlates the positive
anomalies and iron ore deposit, in form of a horizontal or gently
dipping dyke with strike length of 600 m and average width of
110–130 m, within the gneiss complex in the north and trending
south ofthe area. A secondary causative body associated withthe
negative anomalies and inferred as a vertical/near vertical thin
sheet striking northeast–southwest coincided with the granitic
and quartzitic intrusion. The NW–SE and E–W lineament trend
conformed Kibarian and Liberian orogeny cycles of generallyknown structural trends in Nigeria, which shows that the iron
ore deposit is structurally controlled. Depths to sources were
estimated within range ≤ 2–24 m and 37.5–60 m, regarded as
shallow and relatively deep depths, respectively. Ten vertical
boreholes ranging in depth between 50 and 100 m are recommended, five of which require a priority attention to ascertain the
thickness of the primary causative body.