Integrating Satellite Imagery and Aero-radiometric Datasets in Lithological Discrimination and Detection of Hydrothermal Zones at Ikara and its Environs, North-Central of the Basement Complex, Nigeria

Abstract

:  Aero-radiometric data and Landsat-8 Operational Land Imager data were used to identify different rock types in the research area. Bands 4,3,2 and 6,5,4 of Landsat-8 OLI were used for natural and false colour composites to discriminate lithological units. Bands 7,5,3 was utilized for principal component analysis for further lithological discrimination. In addition to clearly visualize the lithological boundaries and regions of mineralization potentials, the use of aero-radiometric data was equally employed. The aero-radiometric data revealed regions where K, eTh and eU natural radionuclide elements (NORMS) were, generated individually for each NORM. Then, a ternary map was generated which revealed the regions of lithological units of the study area. This correlated with results attained from the Landsat-8 OLI. This revealed that lithologies at the northern parts had K>eU/eTh (migmatites, medium to coarse grained granites and porphyritic granites) and lithologies in the southern parts had eTh/eU>K (porphyroblastic gneiss and augen gneiss). From both Landsat and aero-radiometric maps, the presence of a regional fracture was identified trending NW-SE across the study area. The ternary image and K/eTh ratio revealed zones of possible hydrothermal alterations which was observed along the regional fault and shear zones identified within the study area. This suggested that the zones of hydrothermal alterations were structurally controlled. These were further confirmed on ground study and discovered areas where amethyst mineralization and alluvial cassiterite deposits were once mined.