Petrogenesis of fractionated calc-alkaline A-type granites and related fluorite, North Eastern Desert, Egypt | ||
| Frontiers in Scientific Research and Technology | ||
| Volume 6, Issue 1, August 2023 PDF (1.41 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/fsrt.2023.209091.1092 | ||
| Authors | ||
| Omar Amer* 1; Sherif Kharbish2; Ali Maged3 | ||
| 1Geology Department, Faculty of Science, Zagazig University, Sharkia Governorate, Zagazig 44519, Egypt. | ||
| 2Geology Department, Faculty of Science, Suez University, Suez Governorate, El Salam City, 43518, Egypt. | ||
| 3Geology Department, Faculty of Science, Suez University, El Salam City, P.O. Box 4Geology Department, Faculty of Science, Suez University, Suez Governorate, El Salam City, 43518, Egypt3518, Suez Governorate, Egypt | ||
| Abstract | ||
| This study focuses on the petrogenesis of A-type granites and associated fluorite in the Qattar area, Northeastern Desert, Egypt. These granitoids show a geochemical signature typical for an A-type granite, characterized by a slightly peraluminous, highly SiO2, alkalis (Na2O+K2O), U, Rb, Zr, contents, and belong to a group of Ferroan granites with low MgO, CaO, and MnO contents and high FeOtot/ FeOtot+MgO ratios. These rocks emplaced during a late-collisional stage at a temperature of~755.3 °C and pressures from 2.33 to 2.95 kbars under oxidizing conditions (log fO2 -14.85 to -14.91). Moreover, a high 10,000×Ga/Al ratio, negative Eu anomaly, and the tetrad pattern of Qattar alkali–feldspar granites backed up their formation by fractional crystallization and fluid-melt interactions during the late stage of magmatic differentiation. Fluorite mineralization is recorded as four fluorite types (sky blue-, light-yellow-, colorless-, and yellow-type) formed by hydrothermal processes. These fluorites show a wide range of rare earth element variations (∑REE from 76.05 to 166.15) and negative Eu anomaly, which indicates crystallization temperatures above 200 °C. Moreover, Gd / Yb ratios are < 1 in sky blue and light-yellow fluorite and >1 in colorless and yellow fluorites, reflecting various conditions of REE leaching. | ||
| Keywords | ||
| Qattar; Fluorite; Mineralization; Hydrothermal; Granites | ||
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