Document Detail


Radioelement distributions in the Proterozoic granites and associated pegmatites of Gabal El Fereyid area, Southeastern Desert, Egypt.
MedLine Citation:
PMID:  14522238     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Lithologically, the rock types in the Gabal El Fereyid area are dominantly granites with minor amounts of pegmatites. The granites range in composition from tonalite to granite-adamallite with minor acidic dikes, quartz and pegmatite veins. The granite-adamallite is peraluminous and formed as a result of partial melting of amphibole-bearing rocks at depths of approximately 24-30 km and at temperatures of 800-950 degrees C. Among the different rock types, the muscovite-rich pegmatites had the highest U and Th contents (66 and 38 ppm on average, respectively). The high level of radioactivity in pegmatites is attributed to the presence of the radioactive minerals thorianite, uranophane and allanite as confirmed by XRD analysis. Binary relations of Zr/U, Zr/Th, Ce/U and Ce/Th against either U or Th in the granite-adamellite exhibit significant negative correlations indicating that both elements are not preferentially hosted in the accessory minerals phases such as zircon and monazite, but could be associated with major forming minerals such as biotite, muscovite, plagioclase and quartz, or U is situated within labile sites within granite. The uranium and thorium enrichment in the pegmatites is a two-stage process. The primary stage is magmatic whereas the secondary enrichment is from hydrothermal concentration. The magmatic U and Th are indicated by the presence of thorianite and allanite, whereas evidence of hydrothermal mineralization is the alteration of rock-forming minerals such as feldspar and the formation of secondary minerals such as uranophane and pyrite.
Authors:
H H Abd El-Naby; G M Saleh
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine     Volume:  59     ISSN:  0969-8043     ISO Abbreviation:  Appl Radiat Isot     Publication Date:  2003 Oct 
Date Detail:
Created Date:  2003-10-02     Completed Date:  2004-01-28     Revised Date:  2006-04-17    
Medline Journal Info:
Nlm Unique ID:  9306253     Medline TA:  Appl Radiat Isot     Country:  England    
Other Details:
Languages:  eng     Pagination:  289-99     Citation Subset:  IM    
Affiliation:
Nuclear Materials Authority, Box 530 El-Maadi, Cairo, Egypt. hhabdel@yahoo.com
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MeSH Terms
Descriptor/Qualifier:
Desert Climate
Egypt
Environmental Monitoring
Gamma Rays
Geologic Sediments / analysis*
Minerals / analysis*
Radioisotopes / analysis
Radiometry / methods
Silicon Dioxide / analysis*,  classification
Soil / analysis*
Spectrum Analysis / methods
Thorium / analysis*
Uranium / analysis*
Chemical
Reg. No./Substance:
0/Minerals; 0/Radioisotopes; 0/Soil; 0/granite; 7440-29-1/Thorium; 7440-61-1/Uranium; 7631-86-9/Silicon Dioxide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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