Depth Estimation of Magnetic Sources in Katsina State, North-Western Nigeria, Using Aeromagnetic Data

Abstract

This study estimates depths to magnetic sources in Katsina State, north-western Nigeria, using high-resolution aeromagnetic data from eight sheets: Ruma (Sheet 33), Katsina (Sheet 34), Dutsin Ma (Sheet 55), Musawa (Sheet 65), Funtua (Sheet 78), Malumfashi (Sheet 79), Maska (Sheet 101) and Zaria (Sheet 102). The work applies three depth-estimation techniques, namely 3D Euler deconvolution, source parameter imaging (SPI) and analytic signal (AS) depth estimation, to support the interpretation of subsurface structures relevant to mineral exploration. The total magnetic intensity map shows values between 32,933.563 and 33,079.871 nT, reflecting contrasts associated with lithology and structural features. Depth estimates range from 9.039 m, obtained from SPI, to 1,060.994 m, obtained from AS. Shallow magnetic sources, generally less than 150 m deep, occur mainly in the south-eastern sector around Mai-Jiriya and Gwarzo and in the north-western sector around Charanchi and Mani. A NW-SE-trending dyke-like feature through Mahazu and Ungwan Gagarau is consistently indicated at depths of 150-350 m by the three methods, including Euler deconvolution using a structural index of 1. Deeper sources, exceeding 600 m, occur in the north-eastern part of the area and are interpreted as comparatively thick basement rocks. SPI provided useful imaging of undulating basement topography, whereas Euler deconvolution was more effective for structural depth estimation. The agreement among the methods strengthens the interpretation of shallow magnetic sources that coincide with zones of high analytic signal amplitude and structural density. The results identify areas of potential near-surface mineralisation within the Katsina sector of the Schist Belt, subject to ground-based validation and drilling.