ROCK DISCRIMINATION AND GEOLOGICAL MAPPING OFBASEMENT ROCKS AT GABAL GHARIB AREA NORTHEASTERN DESERT OF EGYPT WITH APPLICATION OFLANDSAT ETM AND EGYPTSAT-1 DATA

摘要

Gabal Gharib area comprises Late Proterozoic Precambrian basement rocks of metamorphic and magmatic assemblagesuncomfortably overlain by Miocene-Holocene sedimentary rocks. The calc-alkaline metamorphosed volcanic rocks arethe main rock varieties forming the exposed metamorphic assemblage extruded by Dokhan volcanics and intruded by synto late to post tectonic magmatic intrusions of gabbro-diorite, tonalite-granodiorite (G1), monzogranites-alkali feldspargranites (G2) and alkaline riebeckite granites (G3). Different band ratio ETM images, Landsat ETM-Egyptsat-1 fusedimage data with the spectral signature characterizations together with the data of field study were applied to discriminatethese different basement rock units. Four granitic varieties as well as the metamorphosed older volcanics and youngerDokhan-type volcanics are well discriminated. This study revealed that the Landsat ETM- Egyptsat-1 fused band ratioimage (7/4, 3/7, 4/5) is the best to discriminate the exposed basement rocks and the structural features at Gabal Gharibarea.