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Geophysical magnetic data analyses of the geological structures with mineralization potentials over the southern part of Kebbi, NW Nigeria

Augie Abdulrahaman Idris, Salako Kazeem Adeyinka, Rafiu Adewuyi Abdulwaheed, Jimoh Mufutau Owolabi

Mining Science

2022

Vol. 29

179--203

This study used geophysical data analysis to map and provide useful estimates of the geometry, depth, and magnetization of the magnetic sources, as a continuation and improvement over the earlier analyses in the area. Fugro airborne surveys collected aeromagnetic data for the Nigeria Geological Survey Agency (NGSA) between 2009 and 2010. The study area’s data were processed and analyzed using an improved tilt derivative (TDR) technique and 2D magnetic structural modelling. The result of TDR reveals the horizontal location and extent of the edges of various magnetic sources that formed lineaments. The results from 2D modelling for the selected profiles (PI, P2, P3, P4, and P5) identify zones with a high magnetic anomaly responding to fractures. These fracture regions of the basement complex area could be caused by fault/shear zones. Fault-induced areas on these sub-basin floors are important hosts for hydrothermal mineralization. In comparison to the geological setting, these regions are underlain by quartz-mica schist, biotitehornblende, granite, biotite, gneiss, diorite, migmatite, medium coarse-grained sandstone, ironstones, laterite, siltstones, and clay. These regions could be suitable for mineral exploration and correspond to the Ngaski, Yauri, Magama, Shanga, and Rijau. However, in comparison to the SPI results, the depth/thickness of the sediments that crossed the areas of the sedimentary basin and basement complex zones did not match the results of 2D forward modelling. The SPI technique usually provides an average depth of the magnetic source and is unable to accurately map the undulating basement. While the aforementioned results of 2D forward modelling provide sediment thickness by accurately reflecting basement topography.

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

Augie Abdulrahaman Idris, Salako Kazeem Adeyinka, Rafiu Adewuyi Abdulwaheed, Jimoh Mufutau Owolabi

Geology, Geophysics and Environment

2022

Vol. 48, no. 2

177--193

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.