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The present study focuses on the distribution of natural radionuclides and the determination of radioelement favorability in the Nugrus mylonite rock. The radionuclide contents were measured with a NaI(Tl) detector. The concentrations of U, Th, Ra (in terms of eU), and K in the mylonite studied range from 27 to 247 ppm, from 96 to 377 ppm, from 11 to 166 ppm, and from 1.14 to 3.12%, with the averages of 100 ppm, 201 ppm, 55 ppm, and 2.1%, respectively. The interelement relationships indicate that the radioelement distribution is not only magmatic but also hydrothermal. Variations of migration parameters for uranium indicate fluctuations in physicochemical conditions that lead to U accumulation and leaching processes, which are confirmed by increments and decrements in uranium concentrations. The examined samples demonstrate disequilibrium, with eU/Ra (eU) ranging from 1.32 to 3.26, with an average of 1.95, which suggests uranium addition. Uranium, thorium, and potassium favorability indices of the investigated mylonite rocks indicate moderate favorability of these rocks for uranium and thorium and high favorability for potassium. The F-parameter illustrates the presence of different stages of alterations. Mineralogical investigation indicates the presence of such radioactive minerals as thorite and Uranothorite, of Nb–Ta minerals (columbite and ishikawite), and of zircon and xenotime. [ABSTRACT FROM AUTHOR]

Paleozoic rocks in the Wadi El Sahu area are affected by many major faults in different directions. A reverse fault trending NE‐SW is exposed for about 300 m of its length as it cuts through the Abu Hamata and Adedia formations on the south side of Wadi El Sahu. A secondary ascending hydrothermal solution carrying heavy metals and radioactive minerals passed through the fault plain and the surrounding fractures, forming mineralized and radioactive zone. The mineralized zone thickness ranges from 60 cm to 200 cm along the fault plain. These rocks were analyzed radiometrically using a portable gamma‐ray spectrometer, chemically by employing ICP‐ES and ICP‐MS, as well as mineralogically by both binocular and Environmental Scanning Electron microscope. Gold content was also determined by fire assay. REE and U contents reached up to 2682 and 1216 ppm, respectively. Mineralogical investigations indicated the presence of uraninite, torbernite, autunite, sklodowskite, kasolite as uranium minerals, thorite as a thorium mineral, monazite, allanite and xenotime as REE‐bearing minerals, zircon and columbite as accessory minerals, gold and nickel as precious and base metals, in addition to cassiterite, chalcopyrite, chalcocite and chrysocolla. High REE and U contents are attributed to the circulation of epigenetic U and REE‐bearing hydrothermal solutions along the fault plain and its surrounding fractures. Hydrothermal alteration processes could then be confirmed by the presence of the M‐type tetrad effect in the REE‐patterns of the ferruginous sandstone. The non‐chondritic ratio of Nb/Ta, Zr/Hf and Y/Ho in the studied sandstone may be attributed to the tetrad effect. The Ce and Eu anomaly with unusual REE‐patterns was represented by the presence of conjugated M‐W tetrad effects, indicating either the dual effect of hydrothermal solutions or groundwater with seawater. The results clarify that the tetrad‐effects could be used as evidence for the environment of deposition and as an indication for gold mineralization. [ABSTRACT FROM AUTHOR]