Application of high-resolution gravity data for litho-structural and depth characterisation around Igabi area, Northwestern Nigeria

Abstract

Igabi aerogravity dataset was interpreted to delineate litho-structural architectures that could favour the exploitation of potential economic minerals. The distribution of the gravity anomalies over the area ranged from –67.77 to –53.34 mGal. The upward continued bouguer anomaly maps at distance 500 m, 1 km, 2 km, 3 km, and 4 km revealed the variations of anomalous bodies with general regional trends in NW-SE, E-W, and NE-SW directions. The superimposed analytic signal indicated low amplitude signals for migmatites, schists, less dense felsic rocks (porphyritic granites) and fractures, while areas of high amplitude signals correlated with biotite granitic and gneissic rocks because of the denser mafic minerals in them. The second vertical derivative and tilt derivative maps revealed the anomaly patterns of shallow basement rocks and near circular closures anomalies that are associated with fractures within the granitic rocks. Spectral analysis suggested depth to gravity sources ranging between 0.3 km and 0.67 km for shallow, 0.90 km and 0.97 km for intermediate and 1.5 km to 1.86 km for deep sources, while Euler solution depths ranged from <1392.3 m to >2059 m. The results, therefore, suggested intense deformation of the basement rocks with tectonic framework suitable for mineralisation.