Mapping gold mineral prospectivity based on weights of evidence method in southeast Asmara, Eritrea

Abstract

Eritrea at the southern Nubian shield in northeast Africa has many gold deposits, and has been an important target for exploration. In view of the arid to semi-arid nature of the terrain, there is continuous quest for new methods of mineral exploration. In this study, we highlight the importance of GIS-based weights of evidence (WofE) method in mapping the gold mineral prospectivity of the Ewanet area, southeast Asmara. For the purpose, data was gathered from geological, metallogenic, geochemical and remote sensing analyses of the study area. Seven evidence maps produced from these spatial data sets were used to calculate posterior probabilities and delineate prospectivity areas for gold deposits. The prediction-area plot provides the evaluation of posterior probabilities and indicates that 83% of the existing mineral occurrences are predicted in 19% of the study area. Two types of gold occurrences, i.e., structure-alteration type and quartz-vein type, were identified during field work. It was found that faults are the main ore-controlling factors, and Au geochemical anomaly is prominently correlated with mineralization. We suggest that the identified prospectivity areas of gold exploration in the Ewanet area are well worth carrying out further mineral exploration.