APPLICATION OF GROUND MAGNETIC METHOD FOR DELINEATION SUBSURFACE STRUCTURAL CONTROL ON SULPHIDE ORE DEPOSIT IN BENUE TROUGH; A CASE STUDY OF IKENYI IZZI

Abstract

The sulphide ore mineralization occurrence in the area is structurally controlled. However, wrong structural delineation has led to some recorded mine failures and revenue loss faced by investors and government. Therefore, subsurface structural mapping is crucial for the successful and reliable delineation of sulphide ore enrichment zone within the area. To this effect ground magnetic method was used to appraise the structural elements associated with the sulphide mineralization in Ikenyi Izzi area, part of Southern Benue Trough. The total magnetic field intensity (TMI) was recorded, corrected, and separated into regional and residual magnetic fields. The TMI varies from 33259.7–33329.7nT with an average field value of 33299.4nT. Whereas residual susceptibility value ranges from -36.3–25.7nT with significant magnetic closures which correspond to the areas of low and high susceptibility values. Three dominant structural geometries was identified in the area; NE-SW>NW-SE>N-S with few E-W structures. The NE-SW and some N-S structures characterized areas of high magnetic anomaly closures and are associated with the regional trends of the igneous intrusive rocks, whereas NW-SE structures host the ore deposit (Trending ≥N300°) and dominantly associated with areas of low magnetic anomaly zones. The cross-cutting relationship of the NE-SW, N-S and NW-SE structures infers a close association of the intrusions and mineralization, which was validated by ground truthing. The residual susceptibility values of 1 to 10nT and ≥ 10nT were inferred as shale and intrusive rocks respectively. The implication of this study denotes that missing appropriate structural elements delineation could lead to abortive mines target.