Aeromagnetic mapping of basement structures and mineralisation characterisation of Ilesa Schist Belt, Southwestern Nigeria

Structural and hydrothermal alteration mapping related to orogenic gold mineralization in part of Kushaka schist belt, North-central Nigeria, using airborne magnetic and gamma-ray spectrometry data

“…short-wavelength anomalies in the data, the resulting regional magnetic field of the study area emphasizes the deep-seated, long-wavelength magnetic anomalies. Residualization, as the name implies, is the estimation of expected residual magnetic fields by removing the estimated regional field values over an area or profile from the observed total magnetic field values [22]. The residualization of the TMI data in this study assists in accentuating the shallower magnetic effects at the expense of deeper magnetic sources, which is of prime interest in mineral exploration.…”

“…NaI "Tl" crystal size of 2″ × 2″ was used for the airborne gamma-ray spectrometry survey [59] In order to achieve seamless data and minimize aliased artefacts in the data [60], the TMI data was gridded with grid mesh size of 50 m × 50 m by adopting minimum curvature gridding method [61,62]. The aeromagnetic data was upward continued to a plane height of 200 m in order to remove high-frequency anomalies (which are usually cultural) that stem from sources on or near the ground surface over the study area and amplify the deep-seated geologic structures prior further processing [22]. Due to the proximity of the study area to the equator (i.e.…”

“…The application of airborne geophysical methods such as airborne magnetic, gravity, electromagnetic and radiometric to gold mineralization mapping has been proven to be efficient and effective in mapping targeting elements that are related to orogenic gold mineralization [1,6,7,[11][12][13]22]. The standard processing of geophysical data can be used to delineate mineralization expressions that are not commonly visible during surface geological mapping due to the presence of dense vegetation cover, thick soil cover, size of outcrops and non-existence of surficial manifestations of mineralization footprints [23][24][25][26][27][28][29][30].…”

“…The standard processing of geophysical data can be used to delineate mineralization expressions that are not commonly visible during surface geological mapping due to the presence of dense vegetation cover, thick soil cover, size of outcrops and non-existence of surficial manifestations of mineralization footprints [23][24][25][26][27][28][29][30]. Hence, the integration of appropriate geophysical methods for mapping geologic structures and hydrothermal alteration haloes in relation to orogenic gold mineralization can assist in maximizing prospecting benefits [22,28,30], rather than solely relying on field geological mapping.…”

“…The potential fields of the earth, most especially aeromagnetic method, are well known as an important source of information for studying sub-surface structural framework of basement rocks [6,8,22,[30][31][32]. Aeromagnetic data is not only limited to delineating structural fabrics of tectonically deformed basement rocks, but it is also a veritable tool in investigating magnetomineralogical changes that are related to syn-mineralization hydrothermal alteration subsystem [7,11,26].…”