摘要：The main objective of this study is to carry out regional geological mapping and gold prospecting in the poor savannah Northern Kordofan State, central Sudan. The selection of the study area was based on its favorable gold mineralization geological setting. Syntheses of the various forms of imagery, digital image processing, spectral analysis and office mapping were conducted before going into the field. Field observations, chemical analysis and petrographic investigations have all been integrated with the help of Geographic Information Systems (GIS) to come out with reliable interpretation that can be implemented in similar geologic setting and climatic conditions. A package of digital image processing techniques was applied to Landsat7 Enhanced Thematic Mapper Plus (ETM+) image in order to increase the visual interpretability of the various lithological units for the purpose of geological mapping and delineation of alteration zones, which represent possible target zones for gold mineralization. Different color composite images in addition to the result of image transformation (including Red Green Blue, RGB to Intensity Hue Saturation, IHS; Principal Component Analysis, PCA) were prepared to facilitate the delineation of the main rock groups. Several ratio images were prepared, combined together and displayed in RGB color composites. The outcome of the image processing is the discovery of many alteration and shear zones which trend north-northeast to south-southwest affecting most of the rock types. 139 chip samples were collected from the alteration and shear zones, which were delineated by remote sensing data interpretation and actual field work. They include samples from quartz veins and rock alteration zones which were analyzed by fire assay. All the collected samples proved to be gold-bearing. The Au values range from 0.1 to 84.9 g/ton. Artisanal mining activity in the study area coincided with the remotely sensed data interpretation results conducted in this work, i.e. during the field checkup artisanal miners were found in the places where anomalous signals appeared in the satellite image, thus reinforcing the reliability of the employed approach of remote sensing and GIS for gold prospecting in poor savannah zones.
关键词：Remote sensing Spectral ratioing PCA North Kordofan Gold mineralization
