Discrimination of Neoproterozoic granitic-phases in Southern-Sinai, Egypt. Remote sensing, petrography and geochemistry

Abstract

At Sharm El-Sheikh area a unique association of Neoproterozoic Younger granitic phases is found. These granitic rocks are petrographically identified as monzogranite, syenogranite, alkali feldspar granite, and riebeckite granite.The magma sources of monzogranite and syenogranite are generally of magnesian affinity while those of Alkali-feldspar granite and riebeckite granite are ferroan affinity. Tectonically, the monzogranite and syenogranite were generated during syn- collision tectonic regime and those of Alkali-feldspar granite and riebeckite granite are (within-plate granite). Geochemically they are discriminated into fractionated A-type granites and I-type granite. Alkaline granite samples have the highest ∑REE upto 497.4 ppm while monzogranite samples have the lowest ∑REE reach 153.7. The most conspicuous negative Eu anomaly (Eu/Eu* = 0.1) is recorded in the in alkali feldspar and riebeckite granitoids while monzogranite and syenogranite samples display negligible negative to slight positive Eu anomalies (Eu/Eu* = 1.8).Landsat-8 bands (7, 4, 2) and (7, 3, 5) in RGB used in discrimination and lithologic mapping of the different granitoid rocks. Band rationing technique was successful in discrimination of the two main granitic phases of the study area.