USE OF GAMMA-RAY SPECTROMETRY IN OUTLINING FAVOURABLE SITES FOR POTENTIAL RADIOELEMENT CONCENTRATIONS, G. UMM ZARABIT AREA, CENTRAL EASTERN DESERT, EGYPT

Gebel Umm Zarabit area is located in the central part of the Egyptian Eastern Desert, almost midway between Safaga and Quseir cities on the Red Sea coast. The area comprises a diversity of igneous, metamorphic and sedimentary rocks, ranging in age from Precambrian to Quaternary. The analysis of the present aeroradiospectrometric survey data relies essentially on three interpretation techniques. The first one is the computation of the three radioelements (U, Th and K) favourability indices for locating probable sites for radioelement exploration. The second one is the composite image technique which combines any three radioelement parameters and/or their ratios to generate interpretable composite colour image maps. These maps could help outline potential zones of anomalous radioelement content which may be considered as good targets for radioactive mineral exploration. Meanwhile, the third one is the uranium migration technique, which shows the amount of migrated uranium in and out of the different lithologic units.
The study proved that eTh content is higher than eU content in nearly most rock types of the study area. The maximum readings recorded allover the mapped area reach about 23.54 Ur, 3.49%, 15.25 ppm and 18.78 ppm for TC., K, eU and eTh, respectively. The radiometric levels registered over the lithologically mapped units express their radioactive mineralization content and the mapped radiometric anomalies are spatially correlated with the Upper Cretaceous, Lower Eocene and the younger granitic rocks
Uranium favourability index shows relatively major probabilities of uranium potentiality associated with the younger granites and Post Hammamat felsites. Meanwhile, a high thorium favourability index was related to the Middle Miocene and Upper Cretaceous sediments. The maximum amount of uranium migration out-rate is connected with the younger granites (-83.54%), Post Hammamat felsites (-74.74%) and Dokhan volcanics (-65.35%). This may draw attention to their importance as U-source bodies in the study area