Mapping of Hydrothermal Alteration Minerals Related to Tongue Tonguey (Sirba, Niger) Gold Mineralization Using Landsat 8 OLI Data and Remote Sensing

Abstract

Remote sensing is an effective means of exploring for gold resources. One of Niger's main gold provinces is the Sirba greenstone belt. Gold mineralization in the Tongue Tonguey soils presents interesting anomalies. It was necessary to identify and map the associated hydrothermal alteration. The aim of this work was to map hydrothermal alteration anomalies associated with gold mineralization. Band ratio technique was applied to Landsat 8 OLI data of the study area to highlight surfaces rich in alteration minerals. Band ratios (4/2) and (6/7) were applied to highlight iron minerals (hematite, goethite, jarosite) and alunite/clay minerals (kaolinite, montmorillonite, illite) respectively. Gold anomalies and alteration mineral anomalies were extracted from raster images using the threshold method. Iron minerals and alunite/clay minerals alterations were well associated with the gold anomalies host rocks. Hydrothermal alteration anomalies superimposed effectively on the gold anomalies. They were located in meta-volcano-sediments, along regional faults and at lithological contacts. Gold anomaly zones where iron minerals and alunite/clay minerals alterations was developed constitute favorable zones for gold exploration at Tongue Tonguey.