Application of Remote Sensing and Geographic Information Systems for Gold Potential Mapping in Birim North District of Eastern Region of Ghana -Gold Potential Mapping Using GIS and Remote Sensing

Abstract

Remote Sensing and Geographic Information System (GIS) have played an active role in mineral exploration by helping in the identification or discovery of new gold deposits in most part of the world such as Spain, Nova Scotia (Canada) and Egypt. Different authors have used Remote Sensing and GIS in exploring minerals deposits. Birim North District of the Eastern Region of Ghana is one of the gold-mineralized districts but there is no gold potential map covering the whole district. This research work was aimed at producing a gold potential map covering the whole of Birim North District through the use of Remote Sensing and GIS technique. The Landsat Enhanced Thematic Mapper (ETM+) image of the Birim North was processed by applying the clay-mineral ratio (Band 5 to Band 7) and the principal component analysis. The result was further processed to obtain the alteration map of Birim North District which represented the altered rocks associated with goldmineralization. The Aeromagnetic image of the same area was enhanced by using the Edge Detection Directional Filter and later digitized manually on-screen to produce the lineament map of Birim North District. These results obtained from the Remote Sensing processes were integrated into GIS environment with other geospatial datasets such as the soil geochemical data and geophysical data. The Arcweight of evidence was used as the spatial data integration model in the prediction of the potential gold areas. A total of 250 known gold deposits was used, 180 were used as training samples and 70 were used for the validation. The results obtained from the research work indicated that the best predictors of the new gold deposits were the soil geochemical data, geophysical data and the lineament. The alteration was the least predictor. The gold potential map demarcates 158 km2 (i.e., 32%) of the total of 497 km2 as favourable for the occurences of the gold deposits within the study area. The gold potential map also has a success rate of 88% (i.e, the percentage of the training deposits or points in the predicted favourable gold deposits zones) and a prediction rate of 83% (i.e, the percentage of the validation deposits or points in the predicted favourable gold deposits areas). Many of the mining communities and Newmont Ghana Gold limited mine area were found in the areas associated with relative higher posterior probabilities.