A Qualitative Interpretation of Residual Magnetic Anomaly using Ground Magnetic Data

Abstract

This research aims at analyzing and interpreting residual magnetic anomalies for the determination of subsurface geology of the area under study. We employed the use of ground magnetic survey method for the subsurface delineation of a location within Federal University of Agriculture, Abeokuta, an area of 6600 Π² with geographical coordinates of latitude 7.23707°N to 7.23777°N and longitude 3.43693°E to 3.43858°E. The magnetic data was collected using a G816 proton precision magnetometer. A total of 21 profiles were established along traverses. From these profiles it was seen that the intensities and characteristics nature of the magnetic anomalies, are indicative of the different rocks producing them. Analysis of residual anomaly graph reveals the existence of some structural features such as fault, fractures and contact between rocks and any other subsurface structure of the study area. When the anomaly is higher than the IGRF value, there is said to be a near surface magnetic material (igneous intrusion), but when the anomaly is below the IGRF value, then there is said to be a non-magnetic material such as fault, fracture, etc (sedimentary basin).

Keywords: Proton precession magnetometer; residual; anomaly; qualitative; IGRF