Delineation of Mineralization Zones Using Aeromagnetic Data in Parts of North Central, Nigeria

Abstract

Exploration of solid minerals would have been the best source of income generation for Nigerians, but attention shifted totally to mining of crude oil by successive administrations due to the lure of easier profits from oil production. Naturally the region where the study area is located is blessed enormously with different varieties of solid minerals that are economically and technically viable for exploitation. But, most of these solid minerals are yet to be exploited and so far, the exact locations of these minerals in the subsurface are unknown. To identify and map out lineaments (geological structures) hosting these minerals, a study was carried out with the aim of delineating mineralisation zones using Aeromagnetic Data. The study site covers a total surface area of about 2 18,150 km , geologically, 75% of the total landmass of the area is underlain by Precambrian rocks of the Nigeria Basement complex while the remaining 25% part is occupied by the Cretaceous Sedimentary rocks belonging to Bida Basin. Six different aeromagnetic data sheets were grid knitted into a unified sheet that represents the study area Total Magnetic Intensity (TMI) map using the Geosoft® Oasis Montaj™ software package. For the vital purpose of accurate positioning of the anomalies, the TMI was reduced to magnetic equator. Visual interpretation of Residual Magnetic Intensity (RMI) map revealed that the high and low magnetic anomalies are surrounded by high gradient zones trending in the E-W directions. Furthermore, the filtering techniques used in enhancing identification and mapping of lineaments (shallow geological structures) that accommodates solid mineral deposits are First Vertical Derivative (FVD), Tilt Derivative and CET. The produced maps of each techniques used, agrees with each other by revealing the trends of the lineaments that could possibly host solid minerals. Source Parameter Imaging (SPI) also revealed the average depths of geological structures. Basic dykes and quartz veins are the surface manifestations of NE-SW trend in Basement complex. The revealed lineaments may be inferred to indicate a complex interplay of tectonic activities due to multiple deformational episodes in the area. This may be likely mineralisation zones.