GEOLOGICAL AND MINERALOGICAL STUDIES OF U-Th-BEARING PEGMATITES AT GABAL SUWAIR AND GABAL KHOSH DABA AREA, SAINT CATHERINE, SOUTH CENTRAL SINAI, EGYPT

The pegmatites of Gabal Suwair and Gabal Khosh Daba area are situated in the north of St. Katherine
city, South-Central Sinai. The studied pegmatites considered to be the youngest outcropped rocks following
the arc granitoids and the post-collision granites. They show numerous radioactive anomalies along different
zones in the studied area and spatially belong to the zoned and unzoned both types of pegmatites. The
radiometric investigations of the anomalous pegmatite show that their maximum equivalent uranium content
(eU) is reaching up to 670 ppm while their eTh is reaching up 180 ppm at Gabal Khosh Daba pegmatites.
While the maximum eU and eTh contents at Gabal Suwair pegmatite are 520 and 330 ppm respectively. The
integrated mineralogical studies revealed the occurrence of uranium minerals (i.e. uraninite, brannerite and
carnotite) as discrete large crystals in the zoned pegmatites; while the unzoned ones enclosed samarskite,
betafite, tanteuxenite, uranothorite and thorianite. The presence of uraninite (primary mineral) at the zoned
pegmatite suggest their syngenetically origin during magmatic processes, while, the secondary uranium
minerals presented in the unzoned pegmatite as fissure filling are most probably related to the hydrothermal
activity. Accordingly, the studied widespread mineralized pegmatite could be a promising area for uranium and
thorium exploration and evaluation.