Document Type : Original Article
Authors
1
Geology, Faculty of Science Al-Azhar University Nasr City
2
Geology Department, Faculty of Science, Al Azhar University, Cairo, Egypt.
3
Vice Chairman of the Nuclear Materials Authority, Department of Geology
4
Geology Department, Faculty of Science, Al-Azhar University
5
Geology Department, Faculty of Science, Al-Azhar University , Nasr City, Cairo, PO, Egypt
Abstract
The present study constrains on the geological, petrographical, and geochemical characteristics of the granitic rocks exposed at Gabal El-Magal El-Harami and Wadi El-Hima. The studied area spotlights on the several granitic rock types such as: biotite monzogranites, syenogranites, gneissose biotite granites, and garnet-biotite deformed granites (leucogranites). This area is affected by two major shear zone distributed in the south Hafafit and Nugrus. Petrographically, biotite monzogranites mainly comprises quartz, plagioclase, potash feldspar, biotite, chlorite, muscovite, and sericite. Syenogranites have similarities with the biotite monzogranites but with different contents where plagioclase is the dominant constituent in biotite monzogranites. Garnet-biotite deformed granites are one of the unique varieties in the field of study, which consists of quartz, plagioclase, K-feldspar, garnet, and biotite. These rocks are distinguished by many types of alteration resulting of major shear zones that affected on the region. Biotite monzogranites, syenogranites, and garnet-biotite deformed granites have strong peraluminous (A=CNK>1.1) behaviour and a high in SiO2, Al2O3, and alkali content with low TiO2, MgO, CaO, and Fe2O3 contents. These have a calc-alkaline affinity, intermediate Rb/Sr, high Ba/Sr, high Ba/Rb, and low Na2O/K2O. These granites resemble I-type granites in geochemical terms and were probably produced in a syn-collision regime. The garnet is of magmatic origin, and its textural and chemical characteristics suggest that it is chemically like highly-fractionated I-type granites. The present granites may have been possibly derived from melting of an amphibolitic and metagreywackes lower crust under plated by basaltic magmas.
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