PAN-AFRICAN GRANITOID ROCKS HOSTING JASPEROID VEINS, MASSAK BIRAYKE AREA, NORTH EASTERN DESERT, EGYPT: RADIOACTIVITY AND MINERALOGY

SAID FARAG, MOHAMED EL-HUSSEINY, SALAH EL-BALAKSSY
2017 Nuclear Sciences Scientific Journal  
The studied granitic rocks are mainly distinguished into granodiorites and syenogranites based on their field relationship and petrography. The syenogranites are unconformably overlain by Nubian sandstones from the west. They exhibit an extensive alteration nearby the jasperoid veins such as ferrugination, sericitization, kaolinization, silicification and black manganese dendritic staining. The mineralized reddish brown jasperoid veins intrude the syenogranites and are mostly observed at the
more » ... observed at the highly fractured parts. Some of these jasperoid veins stained with black and reddish brown Mn and Fe oxides associated with bright yellow color of secondary uranium minerals. The radiometric measurements show that the granodiorites and syenogranites exhibits moderate uranium and thorium contents. They display 6 ppm eU and 15 ppm eTh in average for the first and 19 ppm eU and 30 ppm eTh for the later. Unlike, the jasperoid veins attains highest values (eU=250 ppm, eTh=72 ppm) in average. The enrichment of U in the jasperoid veins is probably because of mobilization of U from the syenogranite. Detailed microscopic examinations, X-ray diffraction (XRD) and Environmental Scanning Electron Microscope (ESEM) with EDX microanalysis revealed that the presence of secondary uranium minerals as carnotite and uranophane as well as U-bearing accessory minerals such as betafite, samarskite, zircon and violet fluorite are responsible for radioactivity. Gabal Massak Birayke is located in the Red Sea mountain ranges to the northwest of Hurghada city between lat. 27º 3´ and 27º 10´ N
doi:10.21608/nssj.2017.30782 fatcat:v7fyvu4erbeptc6fjorb56atrq