MINERALOGY, RADIOACTIVITY AND REE-GEOCHEMISTRY OF BATOGA MONZOGRANITE AND ASSOCIATED PEGMATITE, SOUTHEASTERN DESERT, EGYPT

The studied area lies in the southern part of the Eastern Desert of Egypt to the southwest of Ras Benas.
This area is covered by metagabbros, tonalite and monzogranite. The pegmatites occur as elongated, small
pockets and lenses in the monzogranite and display sharp contacts with the host granite. In all cases, the
pegmatites are characterized by obvious simple zonation.
The radiometric studies of monzogranite and associated pegmatite samples show that these rocks are
uraniferous, where their average equivalent uranium contents are 12 ppm and 134 ppm, respectively.
The uraniferous character was confirmed by the average eTh/eU ratios (1.13 and 0.96, respectively). The
average ratios of Pfactor of the studied granites and associated pegmatites are more than one (1.89 and 16.35,
respectively), indicating disequilibrium in U-decay series due to addition of uranium to these rocks. The
present study proved that the presence of uranothorite, uranophane and the uranium-bearing minerals such
as zircon, monazite, allanite and fluorite are responsible for both U and Th contents in the studied granite
and associated pegmatite.
The normalized REE pattern of the monzogranite and associated pegmatite have similar geochemical
characteristics. Where the REE patterns show a LREE relatively enriched feature with strong negative
Eu-anomaly. The characteristic high LREE relative to HREE of the analyzed samples is attributed to the
presence of the allanite, monazite and apatite minerals. The slightly positive Tb anomaly in the studied
granites attributed to its preferential accommodation within the fluorite structure.