RADIOACTIVITY, PETROGENESIS AND RARE EARTH ELEMENTS TETRAD EFFECT OF THE MINERALIZED GRANITE OF GABAL GATTAR, NORTH EASTERN DESERT, EGYPT | ||
| Nuclear Sciences Scientific Journal | ||
| Article 5, Volume 9, Issue 2, October 2020, Pages 63-84 PDF (4.4 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/nssj.2020.265529 | ||
| Author | ||
| EHAB K. ABU ZEID | ||
| Nuclear Materials Authority, Cairo, Egypt | ||
| Abstract | ||
| The batholith of Gabal Gattar is bounded by diorite and granodiorite from the northeastern corner and Hammamat sediments from the northwestern corner. Wadi Belih extends between Hammamat sediments and Gabal Gattar following a major fault trending N75°-80°E. Petrographically, the studied Gattarian granites at GII occurrence composed mainly of potash feldspar, plagioclase and quartz associated with substantial percentage of mica minerals. Modal composition revealed that this granite is quartz-rich syenogranite. Microscopic examination clarifies the presence of two types of secondary radioactive minerals; the first type is syngenetic comprising the minerals that derived from the primary minerals (uraninite-coffinite) as uranophane and kasolite associating the metamict zircon and violet fluorite. The second type of the secondary uranium minerals is epigenetic like uranophane which is the most common secondary uranium mineral that formed by hydrothermal solutions using the silica ions that derived from the silicate minerals. Radioactivity of the studied granite is very high where eU varies between 450 and 4600 ppm with an average 1889.7 ppm, eTh between 0.59 and 900 ppm with an average 80 ppm, Ra between 418 and 2530 ppm with an average 1212 ppm and potassium between 0.01 and 2.40 % with an average 1.05%. The binary relations between the radionuclides show that uranium mineralization in GII occurrence are mainly connected to hydrothermal alteration processes during the late stages of magmatic crystallizations. The ratios (La/Y and Y/Ho)and the anomalies (Ce-and Eu-), in addition to the recorded pattern of REEs tetrad effect (M-type) for the studied granite indicate that this granite is highly evolved and affected by late stage hydrothermal alteration. Mineralogical investigations clarified that U-minerals comprise the primary minerals (uraninite and pitchblende) and the secondary minerals (uranophane and kasolite). | ||
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