RADIOACTIVE SHEAR ZONE AT GABAL ATAITER EL-DAHMI, SOUTHWESTERN SINAI, EGYPT: MINERALOGICAL AND GEOCHEMICAL INVESTIGATIONS

Radiometric survey of Gabal Ataiter El-Dahmi, southwestern Sinai, revealed that, the shear zone exhibit
high radioactive anomalies. The altered younger granites samples show high eU and eTh measurements
relative to the fresh samples suggesting an addition of eU and eTh during the secondary processes affecting
rocks. The data of major and some trace elements of the examined altered younger granites revealed the
enrichment in Al2O3, Fe2O3, FeO, MgO, CaO, Na2O and P2O5, while they shows depletion in
SiO2, TiO2, MnO and K2O relative to the fresh samples. Enrichment of Al2O3 and depletion
of SiO2 could be attributed to sericitization and desilicification respectively during alteration
processes. While the process of Na-metasomatism (albitization) leads to enrichment of Na2O
and depletion of K2O. The enrichments of Fe2O3 and MgO are due to the alteration of biotite
(chloritization). Trace elements of the examined altered younger granites show enrichment in Rb,
Ba, Zr, Y, Nb, Pb and Cu while they reveals depletion in Sr, Zn, Cr and Ni relative tothe
fresh samples. XRD analysis and ESEM examination of the altered younger granites indicated
that, thorite, uranothorite, monazite, xenotime, allanite, zircon and fluorite are the most
important radioactive minerals. Pyrolusite, titanite, columbite-tantalite, hematite, kaolinite
and calcite are also detected.