Geological, Geochemical and Spectrometric Studies on the Trachyte Dykes of Wadi El Hora area, South Eastern Desert, Egypt

Wadi El Hora Phanerozoic alkaline trachyte dykes are located at the southern Eastern Desert of Egypt. These trachyte dykes are located between two strike-slip faults taking the N-S and NW-SE trend. The alkaline trachyte dykes consist essentially of feldspars (albite, oligoclase and sanidine), quartz, and alkali pyroxene (aegirine and aegirine-augite) with zircon, fluorite and opaques as accessory minerals, and finally kaoline and sericite as secondary minerals. The trachyte dykes are rich in high field strength elements Nb, Zr, and Y, they also exhibit typical extensional tectonic alkaline magmatisms and evolved in within plated environment. Rare earth elements (REE) patterns exhibit negative Eu anomalies and are largely uniform and heavily fractionated. These trachyte dykes could be considered as a good target for columbite and zircon exploration. According to a detailed spectrometric analysis, the radioelement concentrations are controlled by post magmatic redistribution since the eU/eTh ratio changed directly with eU concentrations and scattered with eTh. The radiometric measurements of trachyte dykes in the study area show a very wide variation in eU (0.6 – 197.1 ppm with an average 43.73) and eTh (2.4 – 626.3 ppm with an average 109.35) contents. The mineralogical study confirms the presence of kasolite, columbite, zircon, fluorite, molybdenite, monazite, pyrite and ilmenite minerals.