Geophysical assessment for gold mineralization potential over the southern part of Kebbi State using aeromagnetic data

Abstract

The magnetic signatures over the southern part of Kebbi State and its environs were analyzed together with the geological settings of the area to delineate the structures that may host gold mineralization. The aeromagnetic data used was the survey carried out by Fugro airborne surveys between 2005 and 2010 on behalf of the Federal Government of Nigeria. The reduction to equator (RTE), first and second vertical derivatives (FVD and SVD), Centre for Exploration Targeting (CET), analytic signal (AS), source parameter imaging (SPI) and tilt derivative (TDR) techniques were applied to the magnetic data covering the area. The results of the AS technique revealed that the study area is characterized with high amplitudes of magnetic anomalies (above 0.048 nT/m) and these could be of ferromagnetic minerals such as gold. The FVD, SVD, CET and TDR techniques also helped in delineating the lineaments (such as faults, fractures or shears zones) believed to be associated with alteration zones which play an important role in determining gold mineralized zones. The direction of the orientation of these features/lineaments trended in the NE-SW direction. The faults, fractures or shears zones delineated represent veins of possible mineralization. The depth of occurrence to the causative bodies using SPI algorithms was found to be below 137 m. Structures delineated within the area, when compared with the geological setting of the area, correspond to quartz-mica schist, granite, biotite, gneiss, diorite, medium coarse-grained and biotite hornblende granite. Results from these techniques revealed alteration zones that may host gold. These regions correspond to the following areas: SE parts of Yauri and Shanga, Fakai, Ngaski, Zuru, Magama, Rijau, and the eastern part of Wasagu/Danko and Bukkuyum.