Open Journal of Geology, 2014, 4, 228-248 Published Online May 2014 in SciRes. http://www.scirp.org/journal/ojg http://dx.doi.org/10.4236/ojg.2014.45018 How to cite this paper: Rahman, E.A. and Emam, A. (2014) Space-Borne Imagery and Geochemical Characters of Post- Orogenic Dyke Swarms, Fatirah-Abu Zawal District, Eastern Desert of Egypt. Open Journal of Geology, 4, 228-248. http://dx.doi.org/10.4236/ojg.2014.45018 Space-Borne Imagery and Geochemical Characters of Post-Orogenic Dyke Swarms, Fatirah-Abu Zawal District, Eastern Desert of Egypt Ezzat Abdel Rahman, Ashraf Emam Geology Department, Faculty of Science, Aswan University, Aswan, Egypt Email: amezzat2010@gmail.com , ashrafemam99@hotmail.com Received 3 April 2014; revised 2 May 2014; accepted 10 May 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract The Precambrian rocks in Wadi Fatirah-Wadi Abu Zawal area, Eastern Desert of Egypt, are cross- cut by numerous post-orogenic dyke swarms. Image processing techniques are applied to the en- hanced Thematic Mapper plus (ETM+) data for lithological mapping and spectral characterization of these dyke swarms. Band ratios and principal component analysis (PCA) yield conspicuously effective results. Depending on mineralogical and geochemical data, two petrogenetic groups of dyke swarms have been recognized: the first group (mafic dykes) comprises basalt, basaltic ande- site and andesite, while the second group (felsic dykes) corresponds to dacite and rhyolite in composition. The mafic dykes are tholeiitic to calc-alkaline, while the felsic dykes display signi- ficant calc-alkaline affinity. The Na2O, K2O, Ba, Y, Rb, Zr and Th contents increase from basic to acidic dykes and vice versa relative to CaO, MgO, Fe2O3, Sr, V, Co and Ni contents. These dyke swarms have been emplaced in post-collisional, destructive plate margin settings during periods of extension. The basic dykes have characteristics of volcanic arc setting, whereas the acidic dykes display geochemical features of within plate rocks. The chemical differences between the mafic and felsic dyke swarms favor that the two groups of dyke swarms cannot be related to the same magma source, but they are formed from two different parental magmas. Keywords Dyke Swarms, Fatirah, ETM+, Band Ratios, PCA, Geochemistry