Petrogenesis and evolution of the Nuweibi rare-metal granite, Central Eastern Desert, Egypt
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ARABGU2016
Petrogenesis and evolution of the Nuweibi rare-metal granite, Central Eastern Desert, Egypt Ashraf Emam 1 & Basem Zoheir 2,3 & Abdelhady Mohammed Radwan 1,4 & Bernd Lehmann 4 & Rongqing Zhang 5 & Sherif Fawzy 1 & Nicole Nolte 6 Received: 10 July 2018 / Accepted: 9 November 2018 # Saudi Society for Geosciences 2018
Abstract The Nuweibi rare-metal granite in the Central Eastern Desert of Egypt is highly evolved fine- to medium-grained leucogranite affected by pervasive albitization and greisenization. The intrusion holds an important tin–tantalum resource in the Egyptian Eastern Desert. Columbite–tantalite and cassiterite disseminations occur within the granite body, while the quartz ± feldspar veins cutting across the Nuweibi granite host only cassiterite disseminations. Microscopically, quartz and alkali-feldspar are the essential mineral constituents of Nuweibi granite, with minor mica (muscovite + rare biotite), while cassiterite, columbite– tantalite, zircon, allanite, beryl, tourmaline, titanite, and fluorite are accessories. Whole-rock geochemistry and micoanalytical data together with laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) dating of zircon and columbite have been used to constrain the evolution of the granite intrusion and associated mineralization. The Nuweibi granite is weakly peraluminous with extremely low MgO, CaO, TiO2, P2O5, Ba, and Sr contents and elevated Sn, Ta, Nb, and Rb contents. The REE patterns exhibit distinct tetrad effects, as well as negative Eu and Y anomalies. Also, the bulk rock Zr/Hf ratios are consistently < 10. The Nd isotopic system is disturbed and εNd values suggest a juvenile mantle and/or Neoproterozoic crustal source. The U–Pb system in zircon is disturbed and leaked continuously, while the U–Pb age of columbite is ~ 620 Ma. The geochemical and isotopic systematics of the Nuweibi intrusion reflect very advanced degree of fractionation combined with late magmatic fluid overprint which redistributed Sn and other mobile elements, while Ta still characterizes the igneous system. Keywords Nuweibi . Rare-metal granite . Isotopic dating . Tin–tantalum This article is part of the Topical Collection on Current Advances in Geology of North Africa Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12517-018-4051-z) contains supplementary material, which is available to authorized users. * Abdelhady Mohammed Radwan [email protected] 1
Department of Geology, Faculty of Science, Aswan University, Aswan 81528, Egypt
2
Department of Geology, Faculty of Science, Benha University, Benha 13518, Egypt
3
Institute of Geosciences, Kiel University, Ludewig-Meyn Str. 10, 24118 Kiel, Germany
4
Mineral Resources, Technical University of Clausthal, 38678 Clausthal-Zellerfeld, Germany
5
CAS Key Laboratory of Mineralogy and Metallogeny, Chinese Academy of Sciences, Guangzhou 510640, China
6
Geoscience Center Göttingen, Isotope Geology, 337077 Göttingen, Germany
Introduction The Nuweibi rare-m
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