RATIO IMAGE PROCESSING TECHNIQUES: A PROSPECTING TOOL FOR MINERAL DEPOSITS, RED SEA HILLS, NE SUDAN

摘要

The Red Sea Hills Region is a vast span of rugged, harsh and inhospitable sector of the Earth with inimical moon-like terrain, nevertheless since ancient times it is famed to be an abode of gold and was a major source of wealth for the Pharaohs of ancient Egypt. The Pharaohs old workings have been periodically rediscovered through time. Recent endeavours by the Geological Research Authority of Sudan led to the discovery of a score of occurrences with gold and massive sulphide mineralizations. As knowledge of geology and mineralization of the Red Sea Hills improved, it became increasingly apparent that mineral deposits are located along linear structures trending NE-SW and are associated with acid volcanicity. Hydrothermal alterations and weathering processes of the sulphide mineralization produce spectral anomalies that extend beyond the ore body itself. To this end satellite images provide a superb synoptic view of the structural features and the spectral anomalies. Special interest was focused on ratio image processing techniques, whereby false colour composite images were produced using combination of bands in Red, Green and Blue, that rendered maps of alteration zones. Ground-truthing of the outlined areas disclosed the existence of stockworks that contain gold and sulphide mineralization.