期刊名称：Standard Global Journal of Geology and Explorational Research (SGJGER)
印刷版ISSN：2312-7376
出版年度：2014
卷号：1
期号：2
页码：009-026
语种：English
出版社：Standard Global Journals
摘要：The granitoid rocks in G. El Faliq area, southeastern Desert of Egypt, consist of granodiorites, tonalities, monzogranites and alkali feldspar granites. The G. El-Faliq area is composed of ophiolitic mélange, gneisses, older granitoids, younger granitoids and post granitic dykes and veins. Altered granites are encountered at shears and fault zones at G. El Faliq, they rich by uranium and base metals mineralization. Geochemically, the older granitoids are peraluminous to metaluminous granites and fall in volcanic arc granites, while the younger granitoids are calc-alkaline and metaluminous to peralkaline granites and display most of the chemical characteristics of within plat granites setting. The altered granites show argilic facies with a relative depletion in K2O and Na2O + CaO oxides. The comparison between the average of the major oxides of the fresh samples of younger granitoids related to altered ones in the studied area shows that, the younger granitoids rich in SiO2, Na2O and K2O but depleted in TiO2, Al2O3, Fe2O3, FeO, MnO, CaO, MgO and P2O5 related to altered ones. Also, regard to trace elements they are rich in Sr and depleted in Ni, Zn, Zr, Y, Ba, Nb, U and Th. The mineralization of G. El Faliq can be classified on the basis of mode of occurrence and lithological associations into: a) secondary uranium minerals (uranophane), b) niobium-tantalum minerals, c) sulphide minerals and d) accessory minerals. The spectrometric survey revealed the presence of enriched zones with a maximum eU content of 650 ppm and the maximum eTh is 350 ppm. The evidence of hydrothermal mineralization in the alteration of rock-forming minerals such as feldspars and the formation of secondary minerals such as uranophane and pyrite. The pre-existing primary uranium minerals are the source of the present secondary uranium minerals by the action of oxidizing fluids, mobilization of uranium and then redeposition in other forms. Redistribution by circulating meteoric waters might have taken place. Keywords: G. El-Faliq, altered granites, uranium mineralization, spectrometric prospecting
