Delineation of Hydrothermally Altered Zones in Tegina Area, North Central Nigeria
Publication Date : 23/05/2022
Hydrothermally altered areas have been known to be good prospects for gold and copper mineralisation but are difficult to map. Airborne Geophysical data (airborne radiometric and aeromagnetic) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data have been used to circumvent this challenge in many places. This study was aimed at delineating possible hydrothermally altered areas around Tegina and its adjoining areas using Geophysical and ASTER data. Surface structures were extracted from Aeromagnetic data, while Airborne Radiometric and ASTER data using Band ratio and Spectral Angler Mapper (SAM) classification were used to delineate zones of possible hydrothermal alterations. Geological mapping of two selected areas (A and B) were undertaken for the validation of the results from the remotely delineated zones of presumed anomalies, while the soil mineralogical composition was determined by X-ray diffractometer (XRD) technique. The interpreted ASTER data revealed areas of with suspected hydrothermal alterations. These areas also coincided with areas with anomalous K/Th ratios calculated from the radiometric data. Chlorite, montmorillonite, and kaolinite were the minerals identified these areas confirming possible hydrothermal alterations. The structural orientation of these possible hydrothermal trends in the NE-SW and E-W directions from the interpreted aeromagnetic data while the field structural elements were in the NNE-SSW directions. The alteration anomalies were more pronounced in Area A than B as observed from the mineral constituents of the soil samples from A. Argillic alteration is affirmed to be preponderant in Area A and absent in the soil samples from Area B.
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