Document Type : Research and Reference
Authors
1
Nuclear Materials Authority, P. O. Box, 530, El Maadi, Cairo, Egypt
2
Geology Dept., Fac. Sciences, Benha Univ., Egypt.
Abstract
Nuweibi area is situated in the Central Eastern Desert, Egypt, covers an area of about 135km2. The field observations and the detailed petrographic study revealed that the mapped area is distinguished into several rock units: serpentinites, metasediments, metagabbros and older granites that intruded by albitized granites. The radiometric analyses revealed that the studied rocks exhibit low radioactive levels except for the albitized granites that can be attains relatively moderate Eu and eTh contents. The radioactivity of Nuweibi albitized granites may be attributed to the dominance of thorite and some thorium bearing minerals as monazite and uranothorite, moreover, very scarcely grains of secondary uranium minerals as uranophane, autunite and chernikovite. Furthermore, zircon was documented as free grains or as inclusions within crystals lattice of cassiterite, garnet and titanite. Meanwhile, REE signatures are prevalence in allanite, chevkinite, fluorite, zircon, monazite, apatite and manganocoltan giving rise as a potential source for the REE in theses minerals. On the other hand, columbite, tantalite, tapiolite, and cassiterite are dominant as a rare-metal mineralization (NB, Ta and Sn).
The taxopiokilitic texture as well as the prismatic bipyramidal zircon is a strong evidence for the magmatic origin of Nuweibi granite. Unlike the albitization processes give an idea about the Nuweibi granite may have been underwent an extensive hydrothermal alteration mainly Na-metasomatism. In addition to, the presence of characteristic variety of zircon such as mud zircon, as well as columbite, cassiterite, garnet, fluorite and apatite confirming the multistage of hydrothermal metasomatic origin. The significant enrichment of some trace elements in Nuweibi granites during the alteration could be attributed to the existence of some resistant and economic minerals in the study area.
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