AEROMAGNETIC INVESTIGATION OF GEOLOGIC STRUCTURES ASSOCIATED WITH GOLD MINERALIZATION ALONG DANJA, NORTHWESTERN NIGERIA

Abstract

The discovery of petroleum led to a subsequent shift of the Nigerian economy, leading to a
lack of attention to gold exploration, despite the widespread potentials. Gold production
declined during the Second World War period and never recovered as mines were abandoned
by mostly colonial companies, hence the need to study the aeromagnetic field over the study
area. the interpreted aeromagnetic data delineate structures associated with mineralization of
gold along Danja, North Western Nigeria. This was achieved by first determining depth to
basement and then producing a magnetization map showing susceptibility range across the
entire area of study, and to model the shape, location and depth of structures in the study area.
The anomalies on the aeromagnetic map were defined by fitting a first order polynomial to the
total fields, by the method of least squares to obtain the residual field data. First vertical
derivative and analytic signal anomalies computed, defined distinct pattern of the magnetic
signatures. Euler deconvolution applied produced solutions at different location of the area of
study, this shows that the solution plotted clustered around the region where the geological
structures are located with average depths range of 200.2 m to 2229.1 m, with very few
solutions having depths less than 300 m, the most prominent lineament and all major subtle
lineament have a depth range of 200 m to 600 m. Most of the solutions within the mining site
are between 200.2 m to 618.4 m which shows that the structure is deep seated. The possible
flow of fluid that produced the emplacement of Gold mineralization in the area is believed to
be related to the Kalangai fault which trends NE-SW along Malumfashi in the study area. The
susceptibility values obtained from the magnetization map ranges from -0.000666 to
0.000996SI.