Integrated Aeromagnetic and Aero-radiometric Data for delineating Lithologies, Structures and Hydrothermal Alteration Zones in Ganmo–Amoyo–Ojoku Areas, Nigeria

Abstract

Aeromagnetic and aero-radiometric methods have been successfully used to locate zones of mineralization potentials in Ganmo–Amoyo–Ojoku areas by mapping lithology, structures and hydrothermal alteration regions for industrial purposes. The data, sheet 223-Ilorin on a scale of 1:100,000 were obtained from the Nigerian Geological Survey Agency (NGSA) at a height of 80 meters along a series of NE-SW flight lines spaced 500 m interval. The Total Magnetic Intensity data was gridded at 100 m then reduction to the magnetic equator (RTE) was applied to center magnetic anomalies over their respective magnetic source bodies with the aid of Oasis Montaj™ software. Other enhancement techniques applied are first vertical derivative (FVD), analytic signal (AS) and tilt angular derivative (TDR). In addition, the potassium to equivalent thorium (K/eTh) ratio and ternary radiometric maps were revealed to support the delineation process. The interpreted map for magnetic lineaments by delineating the anomaly maxima mostly observed in the southern and eastern portions of the study area extending from Orogun to Apala and Alaya with continuous linear contour patterns. The lineaments range in lengths from 50 m to 1000 m while the orientations range from NE-SW to NW-SE. The equivalent ratio of potassium-thorium and ternary map revealed lithological units and hydrothermal alterations within the basement complex. From this study, volcanic intrusions, lineament structures, and hydrothermal alteration zones were delineated.