Mapping of Hydrothermal Alteration Zones for Mineral Exploration in Kokona Area of Nasarawa State Nigeria

Abstract

Hydrothermal alteration is a change of pre-existing rocks or minerals caused by the activity of hot solutions, such as fluids accompanying or heated by magma. Landsat 7ETM+ of Kokona local government area of Nasarawa State of Nigeria was used to determine and map zones of hydrothermal alterations. Image processing methods used includes image enhancement, band ratio, false colour composition. Band ratios 3/1 and 5/4 suggested the presence of iron-oxides minerals and hydroxyl minerals respectively. Clay mineralization was detected using band ratio 5/7.While false colour composite of bands 7:4:2 was employed to delineate potential locations of hydrothermal alteration zone. Nigeria Sat-X of the same study area was used to identify zones of lineament locations. The bands were layer stacked and band 3 was found suitable for the extraction of lineaments and the red lines show zones of lineament and it was also overlaid on the RGB colour composite image. Nigeria Sat-X was also used for the land use/land cover analysis through supervised classification techniques which shows the various land use patterns in the study area. The satellite image map gotten from the identification of the hydrothermal alteration zones were compared with the pre-existing geology of the study area, which shows other detected potentially interesting sites that are absent in the geological map of the study area. It is envisaged that the incorporation of intelligent systems in GIS would particularly stimulate the application and realization of the simulation, modelling and investment decisions capabilities for mineral exploration in Nigeria.