The use of enhanced Landsat-TM image in the characterization of uraniferous granitic rocks in the Central Eastern Desert of Egypt

Abstract

The discovery of uranium deposits is more likely if we can identify favourable setting and target areas on the basis of related geological features, such as favourable host rocks, altered zones and structural lineaments. The synoptic view of the enhanced Landsat-TM imagery covering the Central Eastern Desert enabled the author to recognize and interpret these geological features. The coloured composite ratio image produced from combination of 2/4 × 7 (red), 5/7 × 3 (green) and 5/3 × 7 (blue) band ratios was used to classify the exposed younger granitic masses into three groups, namely Gl, G2 and G3. Each of the granitic groups possesses certain image characteristics, such as colour and surface texture. Moreover, the major tectonic features associated with younger granitic bodies were identified from the Landsat image.

Known uranium deposits are recognized to be associated with the youngest granitic group G3. This granite forms circular to elongate shaped, slightly fractured and weathered bodies, invaded by a few individual dikes. They also possess sharp contacts and light magenta colour on the ratioed TM images. The colour composite ratio image enhances the alteration zones associated with the uranium mineralized areas in Gabble (G.) El Mistake and Gabal El Eradiya as light cyan in colour. Moreover, the mineralized zones are also found to be associated with the major N 35° W and N 65° E faults as well as ENE trending dikes. The characteristic image features (colour, surface texture, topographic expression, etc) associated with the uraniferous granites can be used for further searches of uranium deposits in other areas.