Edge detection and magnetic basement depth of Danko area, northwestern Nigeria, from low-latitude aeromagnetic anomaly data

Abstract

This study aims at estimating depths and boundaries of magnetic source bodies, in order to provide an indirect insight into subsurface geologic features within Danko area of Kebbi state. The study area is located within low magnetic latitude. Hence, the total magnetic intensity anomaly map was reduced to the magnetic equator. This is to center magnetic anomalies over their respective magnetic source bodies, which equally makes the interpretation of sources easier. Matched filtering of the reduced-to-equator (RTE) magnetic anomaly map indicates that the anomalies could be represented by two equivalent layers with some additional noise. The estimated mean depths of burial for the regional and residual sources are 1000 m and 500 m, respectively. Horizontal gradient magnitude and tilt derivative methods carried out on the RTE aeromagnetic anomaly map facilitated the identification of two distinct geologic trends bounded by a prominent fault suspected to be the documented Yelwa fault. Furthermore, the analytic signal map showed magnetic basement depth values between 50 and 900 m with an average value of 475 m, indicating a compelling alignment of results with the 500 m depth value for the residual matched filter layer. Several mineral occurrences have been found within the outcropping basement rocks of the study area. Hence, the combined appraisal of source edge locations and magnetic basement depth estimates offers useful information of the underlying basement configuration, which is highly essential for mineral exploration targets that are mostly obscured by regolith cover.