Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data
The Ediacaran peralkaline granites, which were emplaced during the post-collisional tectonic extensional stage, have a limited occurrence in the northern tip of the Nubian Shield. In this contribution, we present new mineralogical and geochemical data of Mount El-Sibai granites from the Central East...
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MDPI AG
2023-08-01
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| Online Access: | https://www.mdpi.com/2075-163X/13/8/1039 |
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| author | Mabrouk Sami Hassan Osman Awaad F. Ahmed Khairy S. Zaky Rainer Abart Ioan V. Sanislav Kamal Abdelrahman Mohammed S. Fnais Wenzhou Xiao Hassan Abbas |
| author_facet | Mabrouk Sami Hassan Osman Awaad F. Ahmed Khairy S. Zaky Rainer Abart Ioan V. Sanislav Kamal Abdelrahman Mohammed S. Fnais Wenzhou Xiao Hassan Abbas |
| author_sort | Mabrouk Sami |
| collection | DOAJ |
| description | The Ediacaran peralkaline granites, which were emplaced during the post-collisional tectonic extensional stage, have a limited occurrence in the northern tip of the Nubian Shield. In this contribution, we present new mineralogical and geochemical data of Mount El-Sibai granites from the Central Eastern Desert of Egypt. The aim is to discuss their crystallization condition, tectonic setting, and petrogenesis as well as the magmatic evolution of their associated mineralization. Mount El-Sibai consists of alkali-feldspar granites (AFGs) as a main rock unit with scattered and small occurrences of alkali-amphibole granites (AAGs) at the periphery. The AAG contain columbite, nioboaeschynite, zircon and thorite as important rare metal-bearing minerals. Geochemically, both of AFG and AAG exhibit a highly evolved nature with a typical peralkaline composition (A/CNK = 0.82–0.97) and formed in within-plate anorogenic setting associated with crustal extension and/or rifting. They are enriched in some LILEs (Rb, K, and Th) and HFSEs (Ta, Pb, Zr, and Y), but strongly depleted in Ba, Sr, P and Ti with pronounced negative Eu anomalies (Eu/Eu* = 0.07–0.34), consistent with an A-type granite geochemical signature. The calculated T<sub>Zrn</sub> (774–878 °C) temperatures indicate that the magma was significantly hot, promoting the saturation of zircon. The texture and chemistry of minerals suggest that they were crystallized directly from a granitic magma and were later subject to late- to post-magmatic fluids. Both granitic types were most likely generated through partial melting of a juvenile crustal source followed by magmatic fractionation. The lithospheric delamination is the main mechanism which causes uplifting of the asthenospheric melts and hence provides enough heat for crustal melting. The produced parent magma was subjected to prolonged fractional crystallization to produce the different types of Mount El-Sibai granites at different shallow crustal levels. During magma fractionation, the post-magmatic fluids (especially fluorine) contribute significantly to the formation of rare metal mineralization within Mount El-Sibai granites. |
| first_indexed | 2024-03-10T23:42:31Z |
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| id | doaj.art-52ceff9ae00d44faa1a5719f826bacb5 |
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| language | English |
| last_indexed | 2024-03-10T23:42:31Z |
| publishDate | 2023-08-01 |
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| spelling | doaj.art-52ceff9ae00d44faa1a5719f826bacb52023-11-19T02:20:40ZengMDPI AGMinerals2075-163X2023-08-01138103910.3390/min13081039Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry DataMabrouk Sami0Hassan Osman1Awaad F. Ahmed2Khairy S. Zaky3Rainer Abart4Ioan V. Sanislav5Kamal Abdelrahman6Mohammed S. Fnais7Wenzhou Xiao8Hassan Abbas9Geology Department, Faculty of Science, Minia University, El-Minia 61519, EgyptGeology Department, Faculty of Science, Minia University, El-Minia 61519, EgyptGeology Department, Faculty of Science, Minia University, El-Minia 61519, EgyptGeology Department, Faculty of Science, Minia University, El-Minia 61519, EgyptDepartment of Lithospheric Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, AustriaEconomic Geology Research Centre (EGRU), College of Science and Engineering, James Cook University, Townsville, QLD 4811, AustraliaDepartment of Geology & Geophysics, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi ArabiaDepartment of Geology & Geophysics, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi ArabiaHunan Key Laboratory of Rare Metal Minerals Exploitation and Geological Disposal of Wastes, School of Resource Environment and Safety Engineering, University of South China, Hengyang 421001, ChinaGeology Department, Faculty of Science, Assiut University, Assiut 71526, EgyptThe Ediacaran peralkaline granites, which were emplaced during the post-collisional tectonic extensional stage, have a limited occurrence in the northern tip of the Nubian Shield. In this contribution, we present new mineralogical and geochemical data of Mount El-Sibai granites from the Central Eastern Desert of Egypt. The aim is to discuss their crystallization condition, tectonic setting, and petrogenesis as well as the magmatic evolution of their associated mineralization. Mount El-Sibai consists of alkali-feldspar granites (AFGs) as a main rock unit with scattered and small occurrences of alkali-amphibole granites (AAGs) at the periphery. The AAG contain columbite, nioboaeschynite, zircon and thorite as important rare metal-bearing minerals. Geochemically, both of AFG and AAG exhibit a highly evolved nature with a typical peralkaline composition (A/CNK = 0.82–0.97) and formed in within-plate anorogenic setting associated with crustal extension and/or rifting. They are enriched in some LILEs (Rb, K, and Th) and HFSEs (Ta, Pb, Zr, and Y), but strongly depleted in Ba, Sr, P and Ti with pronounced negative Eu anomalies (Eu/Eu* = 0.07–0.34), consistent with an A-type granite geochemical signature. The calculated T<sub>Zrn</sub> (774–878 °C) temperatures indicate that the magma was significantly hot, promoting the saturation of zircon. The texture and chemistry of minerals suggest that they were crystallized directly from a granitic magma and were later subject to late- to post-magmatic fluids. Both granitic types were most likely generated through partial melting of a juvenile crustal source followed by magmatic fractionation. The lithospheric delamination is the main mechanism which causes uplifting of the asthenospheric melts and hence provides enough heat for crustal melting. The produced parent magma was subjected to prolonged fractional crystallization to produce the different types of Mount El-Sibai granites at different shallow crustal levels. During magma fractionation, the post-magmatic fluids (especially fluorine) contribute significantly to the formation of rare metal mineralization within Mount El-Sibai granites.https://www.mdpi.com/2075-163X/13/8/1039fractional crystallizationrare metalsperalkaline granitecolumbiteMount El-SibaiNubian Shield |
| spellingShingle | Mabrouk Sami Hassan Osman Awaad F. Ahmed Khairy S. Zaky Rainer Abart Ioan V. Sanislav Kamal Abdelrahman Mohammed S. Fnais Wenzhou Xiao Hassan Abbas Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data Minerals fractional crystallization rare metals peralkaline granite columbite Mount El-Sibai Nubian Shield |
| title | Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data |
| title_full | Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data |
| title_fullStr | Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data |
| title_full_unstemmed | Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data |
| title_short | Magmatic Evolution and Rare Metal Mineralization in Mount El-Sibai Peralkaline Granites, Central Eastern Desert, Egypt: Insights from Whole-Rock Geochemistry and Mineral Chemistry Data |
| title_sort | magmatic evolution and rare metal mineralization in mount el sibai peralkaline granites central eastern desert egypt insights from whole rock geochemistry and mineral chemistry data |
| topic | fractional crystallization rare metals peralkaline granite columbite Mount El-Sibai Nubian Shield |
| url | https://www.mdpi.com/2075-163X/13/8/1039 |
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