Geophysical Evaluation of Gold Potential in Southeastern Part of Kafin-Koro, Northwestern Nigeria

Abstract

Gold mineralization in Nigeria is traversed by regional northwest - southeast lineaments or shear zone which have been considered as continental extension of oceanic transform fault - fracture zone, and it is suggested that the migmatization and metamorphic deformation of the metasedimentary and metavolcanic rocks gave rise to dispersion of gold in quartz veins within the Nigeria basement complex. Combined geophysical methods have been used in the exploration for ore mineral bodies. Induced polarization (IP) technique has proved favourable for mineral exploration in hard rock terrain, as well as for ground water exploration and environmental geology studies. Also, magnetic technique has been used in identifying massive sulfide hosted quartz veins. The study area lies within the Kushaka schist Formation of the north-western block of Nigeria basement complex and Nigeria metallogeny province, the formation has been intruded by large volumes of granitic rocks that led to extensive migmatization of metasedimentary and metavolcanic rocks carrying substantial gold mineralization. Combined magnetic and IP and resistivity imaging technique was used in the study. The magnetic profiles in the study area showed anomalies of varying amplitudes. The variation in amplitudes of the residual intensity may be due to the presence of geological structures such as faults, dykes and contacts in the area. The total magnetic intensity map of the area exhibits zonation and alteration that indicates hydrothermal alteration which is usually associated with mineralization probably as a result of intrusion. Observed apparent resistivity and IP data presented as pseudo-section and 2-D inverted resistivity-IP mode show a qualitative idea of resistivity and chargeability distribution in the subsurface. The ground magnetic survey generally suggests a step or an edge structures like dyke or intrusion, such structures are of interest may hold mineralization at certain depth