Mineral Chemistry of Two-Mica Granite Rare Metals: Impact of Geophysics on the Distribution of Uranium Mineralization at El Sela Shear Zone, Egypt

DOI: 10.4236/ojg.2014.44011   PDF   HTML   XML   5,852 Downloads   8,279 Views   Citations


The present work aims at identifying Nb-Ta-, Zr-Hf-, REE-, Th-U-bearing two-mica granite from geological, geophysical cross-sections and mineral chemistry studies from three boreholes at G. El Sela shear zone. Microscopically, the three boreholes are composed mainly of two-mica granite. They are composed of K-feldspar, plagioclase, quartz, biotite and muscovite. Accessories are pyrite, zircon, fluorite, rutile, monazite with Th-U-mineralization identified by scanning electron microscope (SEM) and electron probe-microanalyses (EPMA). Chlorite, muscovite, sericite, kaolinite are secondary minerals. Geochemically, two-mica granite boreholes are A-type granites and peraluminous characteristics. They are enriched in large ion lithophile elements (LILE; Ba, Rb and Sr), high field strength elements (Y, Zr and Nb), and LREE but depleted in HREE with negative Eu anomaly. U-enrichment associated with chloritization, muscovitization, albitization, sericitization, kaolinization and argillization results from convective hydrothermal circulation of fluids through brittle structures along the ENE-WSW main shear zone. The ratios Nb/Ta (7.7 - 17.7) and Zr/Hf (16.9 - 26.4) are relatively enriched in the lighter isovalents Ta and Hf. The accessory minerals observed in the two-mica granites are represented by metallic sulfides (pyrite, arsenopyrite, chalcopyrite, galena and sphalerite), Nb-rutile, Hf-zircon, fluorite, monazite, columbite, betafite, thorite, phosphothorite, uranothorite, brannerite, uraninite, coffinite and pitchblende at G. El Sela shear zone. Uraninite with a low Th content indicates a hydrothermal origin of U-mineralization, Thorite, uranothorite, monazite and zircon is the main uranium bearing minerals of magmatic origin within the enclosing granite. The primary U-mineralization has been observed in two boreholes. In order to illustrate the geophysical signature of El Sela U-mineralization, the radiometric, magnetic, and VLF-EM data as well as radon concentration are included. The magnetic, electrical conductivity and radiometric profiles were produced from detailed ground surveys. The shear zone is characterized by relatively weak levels for both K and eTh, but very high eU anomalies (<3500 ppm), Therefore, the Sela shear zone acts as a good trap for U-mineralization. The Sela Shear zone coincides with positive conductivity anomalies, which are the most prominent features on the respective profiles. The magnetic field over the Sela shear zone is also conspicuous by the sharp contrast which makes with the strong negative signatures of the altered microgranite. The radon distribution map showed the presence of seven high anomalies that are mostly controlled by the structures due to the easy movement of radon through them.

Share and Cite:

Gaafar, I. , Cuney, M. and Gawad, A. (2014) Mineral Chemistry of Two-Mica Granite Rare Metals: Impact of Geophysics on the Distribution of Uranium Mineralization at El Sela Shear Zone, Egypt. Open Journal of Geology, 4, 137-160. doi: 10.4236/ojg.2014.44011.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Cuney, M. (2009) The Extreme Diversity of Uranium Deposits. Mineralium Deposita, 44, 3-9. http://dx.doi.org/10.1007/s00126-008-0223-1
[2] IAEA (2009) World Distribution of Uranium Deposits (UDEPO) with Uranium Deposit Classification. IAEA, Vienna, IAEA-TECDOC-1629, 117 p.
[3] Cuney, M., Le fort, P. and Wang, Z.X. (1984) Uranium and Thorium Geochemistry and Mineralogy in the Manaslu leucogranite (Nepal, Himalaya). Geology of Granites and Their Metallogenetic Relations (Proceedings of a Symposium), Nanjing, 1982, University Sceinces Editions, 853-873.
[4] Poty, B., Cuney, M. and Friedrich, M. (1986) Uranium Deposits Spatially Related to Granites in the French Part of the Hercynian Orogeny, Vein Type Uranium Deposits. IAEA-TECDOC-361, IAEA, Vienna, 215-246.
[5] Friedrich, M.H., Cuney, M. and Cregu, G. (1989) Uranium Enrichment Processes in Peraluminous Magmatism. International Atomic Energy Agency (IAEA)-TC-571/2.11-35.
[6] Rameshbabu, P.V. (1999) Rare Metal and Rare Earth Pegmatites of Central India. Special Issue on Rare Metal and Rare Rarth Pegmatites of India. Exploration and Resarch, 12, 7-52.
[7] Pal, D.C., Mishra, B. and Bernhardt, H.J. (2007) Mineralogy and Geochemistry of Pegmatite-Hosted Sn-, Ta-Nb-and Zr-Hf-Bearing Minerals from the Southereastern Part of the Bastar-Malkangiri Pegmatite Belt, Central India. Ore Geology Reviews, 30, 30-55.
[8] Jiashu, R. and Zehong, H. (1982) Forms of Uranium Occurrence and Its Distribution in Uraniferous Granites. In: Geology of Granites and Their Metallogenetic Relations, Sciences Press, Beijing, 621-635.
[9] Ibrahim, M.E. (1986) Geologic and Radiometric Studies on Um Ara Granite Pluton, South East Aswan, Egypt. Unpublished M.Sc. Thesis, Mansoura University, Mansoura.
[10] Abdalla, H.M., Matsueda, H., Ishihara, S. and Miura, H. (1994) Mineral Chemistry of Albite-Enriched Granitoids at Um Ara, Southeastern Desert, Egypt. International Geology Review, 36, 1067-1077. http://dx.doi.org/10.1080/00206819409465505
[11] Roz, M.E. (1994) Geology and Uranium Mineralization of Gabal Gattar Area, North Eastern Desert, Egypt. Unpublished M.Sc. Thesis, Al Azhar University, Cairo, 175 p.
[12] Abu Dief, A. (1985) Geology of Uranium Mineralization in Missikat, Qena-Safaga Road, Eastern Desert, Egypt. Unpublished M.Sc. Thesis, Assiut University, Assiut, 242 p.
[13] Osmond, J.K., Dabous, A.A. and Dawood, Y.H. (1999) U Series Age and Origin of Two Secondary Uranium Deposits, Central Eastern Desert, Egypt. Economic Geology, 94, 273-280.
[14] Abdel Naby, H.H. (2008) Genesis of Secondary Uranium Minerals Associated with Jasperoid Veins, El Erediya Area, Eastern Desert, Egypt. Mineralium Deposita, 43, 933-944.
[15] NMA (Nuclear Material Authority) of Egypt (2003-2013) El Sela Development Project, Internal Reports.
[16] Gaafar, I.M. (2005) Applications of Geological and Geophysical Survey for Defining the Uranium Potentiality of Some Younger Granites in the Eastern Desert of Egypt. Unpublished Ph.D., Faculty of Science, Mansoura University, Mansoura, 186 p.
[17] Ali, K.G. (2011) Structural Control of El Sela Granites and Associated Uranium Deposits, South Eastern Desert, Egypt. Arabian Journal of Geosciences.
[18] Abdel Gawad, A.E., Orabi, A.H. and Bayoumi, M.B. (2014) Uranium Evaluation and Its Recovery from Microgranite Dike at G. El Sela area, South Eastern Desert, Egypt. In Press.
[19] Gaafar, I.M., Ghazala, H.H., Ibrahim, T.M. and Ammar, S.E. (2006) Gamma-Ray Spectrometry Studies for A Promising Vein Type Uranium Mineralization, South Eastern Desert, Egypt. Proceedings of 4th International Symposium on Geophysics, Tanta, 2006, 445-456.
[20] Gaafar, I.M., Ghazala, H.H., Ibrahim, T.M. and Ammar, S.E. (2006) Application of Ground Magnetic Survey for Defining the Subsurface Structural Pattern of West Abu Ramad Shear Zone, Southern Eastern Desert, Egypt. The 8th SEGJ International Symposium-Imaging and Interpretation, Kyoto, 2006, 487-492.
[21] Gaafar, I.M., Ghazala, H.H., Ibrahim, T.M. and Ammar, S.E. (2006) Conductivity Mapping Using VLF-EM Ground Survey For Promising Vein Type Uranium Mineralization, South Eastern Desert, Egypt. 8th International Conference of the Geology of the Arab World, Cairo University, Giza.
[22] Mayya, Y.S., Eappen, K.P. and Nambi, K.S. (1998) Methodology for Mixed Field Inhalation in Monazite Areas Using a Twin-Cup Dosimeter with Three-Track Detector. Radiation Protection Dosimetry, 77, 177-184. http://dx.doi.org/10.1093/oxfordjournals.rpd.a032308
[23] Debon, F. and Lefort, P. (1988) A Cationic Classification of Common Plutonic Rocks and Their Magmatic Associations: Principles, Method, Applications. Bulletin de Mineralogie, 111, 493-510.
[24] Sun, S.S. and McDonough, W.F. (1989) Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes. In: Saunders, A.D. and Norry, M.J., Eds., Magmatism in the Ocean Basins, Vol. 42, Geological Society, Special Publications, London, 313-345.
[25] Pearce, J.A., Harris, N.B.W. and Tindle, G. (1984) Trace Elements Discrimination Diagram for the Tectonic Interpretation of Granitic Rocks. Journal of Petrology, 25, 956-983.
[26] Saunders, A.D., Nory, M.J. and Tarney, J. (1991) Fluid Influence on the Trace Element Compositions of Subduction Zone Magmas. In: Tarney, J., Pickering, K., Knipe, R. and Dewey, J., Eds., The Behaviour and Influence of Fluids in Subduction Zones, Philosophical Transactions of the Royal Society of London, 335, 377-392.
[27] Nakamura, N. (1974) Determination of REE, Ba, Fe, Mg, Na and K in Carbonaceous and Ordinary Chondrites. Geochimica et Cosmochimica Acta, 38, 757-775. http://dx.doi.org/10.1016/0016-7037 (74)90149-5
[28] Abd Elaal, H.A. (2006) Geochemistry and Processing of Some Valuable Metals from Mineralized Two Mica Granites, South Eastern Desert, Egypt. Unpublished M.Sc. Thesis, Cairo University, Giza, 110 p.
[29] Speer, J.A., Solberg, T.N. and Becker, S.W. (1981) Petrography of the Uranium-Bearing Minerals of the Liberty Hill Pluton. South Carolina: Phase Assemblage and Migration of Uranium in Granitoid Rocks. Economic Geology, 76, 2162-2175. http://dx.doi.org/10.2113/gsecongeo.76.8.2162
[30] Wang, R., Cheng, F.F. and Monchoux, P. (1992) Minéraux disséminés comme indicateurs du caractère pegmatitique du granite de Beauvoir, massif d’échassières, Allier, France. Canadian Mineralogist, 30, 763-770.
[31] Janeczek, J. and Ewing, R.C. (1992) Structural Formula of Uraninite. Journal of Nuclear Materials, 190, 128-132. http://dx.doi.org/10.1016/0022-3115(92)90082-V
[32] Miller, J.M. and Ostle, D. (1973) Radon Measurement in Uranium Prospecting. Uranium Exploration Methods, Proceedings of a Panel, Vienna, 10-14 April 1972.
[33] Fleischer, R.L. and Mogro-Campero, A. (1978) Mapping of Integrated Radon Emanation for Detection of Long-Distance Migration of Gases within the Earth: Techniques and Principles. Journal of Geophysical Research, 83, 3539-3549. http://dx.doi.org/10.1029/JB083iB07p03539
[34] Weyer, S., Münker, C., Rehkomper, M. and Mezger, K. (2002) Determination of Ultra-Low Nb, Ta, Zr and Hf Concentrations and the Chondritic Zr/Hf and Nb/Ta Ratios by Isotope Dilution Analyses with Multiple Collector ICP-MS. Chemical Geology, 187, 295-313. http://dx.doi.org/10.1016/S0009-2541(02)00129-8
[35] Linnen, R.L. and Cuney, M. (2008) Granite-Related Rare-Element Deposits and Experimental Constraints on Ta-Nb-W-Sn-Zr-Hf Mineralization. In: Linnen, R.L. and Samson, I.M., Eds., Rare-Element Geochemistry and Mineral Deposits: Geological Association of Canada, GAC, Short Course Notes, 17, 45-67.
[36] Mann, A.W. and Deutscher, R.L. (1980) Solution Geochemistry of Lead and Zinc in Water Containing Carbonate, Sulfate and Chloride Ions. Chemical Geology, 29, 293-311.

comments powered by Disqus

Copyright © 2020 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.