الفهرس 
Gealigecal setiingOnly 14 pages are availabe for public view
 |  | from | 217 |  |  |
| | | from | 217 | | |
Abstract
Three different localities of alkaline granite occurrences have been recognized in Southeastern Sinai area: Sharm ElSheikh area covers about km Wadi Yahmid area about and North Nuweiba area about km. They are intruded either in alkali feldspar granite or in monzogranite. The rocks belong to two petrographic types: subsolvus and hypersolvus alkaline granites. The alkaline granites are divided into aegirineaugite arfvedsonite granites, aegirine arfvedsonite granites and riebeckite granites. The aegirineaugite arfvedsonite granite is considered as the most abundant type of alkaline granites and is composed of Kfeldspar, quartz, Bplagioclase, arfvedsonite, aegirineaugite,(Bacmite , Bbiotite and Baegirine. Zircon is the most characteristic accessory mineral. Several enclaves of dark grey to black in colour are hosted in alkaline granites. They are composed of alkaline syenitic and aegirineaugite arfvedsonite microgranite. Also, composite enclaves are observed where the syenitic enclaves are rimed by aegirineaugite arfvedsonite microgranites. The alkaline granite suites are peralkaline to metaluminous and display a typical geochemical characteristics of Atype granite such as high FeOT/MgO, high SiO?, absolute high content of alkali, enriched in rare earth elements (REE) (except Eu), Y, Zr, Nb, Ce, Ga/Al and Ta and have low CaO, MgO, Al?O?, Sc and Sr. The suites are identified as within plate granites. The pathogenesis model of alkaline granite suites involve the generation of an alkali basaltic magma derived from an enriched mantle source followed by fractional crystallization to form syenite, aegirineaugite arfvedsonite microgranite then the other types of alkaline granites.