MINERALOGY AND GEOCHEMISTRY OF A NEW URANIUM OCCURRENCE AT THE DECANT OF WADI EL REDDAH, NORTHEASTERN DESERT, EGYPT

Gattar granites are affected by widespread deuteric and post magmatic hydrothermal activities.
Hydrothermal alterations associated U-mineralization in the host granites include hematitization,
sericitization, episyenitization (desilicification) and fluoritization. Alkali metasomatism is represented by
microclinization, sericitization and muscovitization of alkali feldspar and plagioclase. Two new radioactive
occurrences were discovered namely GXXIII and GXXIV. The first radioactive occurrences is located
150-180 m from the contact between the Gattarian granite and the Hammamat molasse sediments. The
intersection show highly hematitized hallows with deep brown to reddish pink color associating some
remarkable silicification. The other radioactive location is controlled by several factors mainly represented
by the NE-SW basic dyke of 2-3 m thickness and bound the radioactive spots from the north. This radioactive
location is located some 350 m from the GXXIV location and is more than 0.5 Km away from the granite-
Hammamat contact zone. The location includes three radioactive spots arranged along major shear zone
trending N25E-S25W.
Generally, loss and gain calculations indicate that the altered samples exhibit an increase in total iron,
K, Mn, Al, Ca and Mg and decrease in Na, P, Si, L.O.I. and Ti, in addition to elevated contents of Cu,
Co, Pb, Cs, Y, Ga, Hf, Sn, V, Nb, Rb, Ta, Th, U, Tl, Zr, W, Zn and depleted in Ba, Sr and Ni. Y/Ho ratios
value show complexation with fluorine and carbonates which is confirmed by the presence of fluorite and
calcite.
Hydrothermal alteration during late magmatic stage is identified by the unusual Zr/Hf, Sr/Eu, Nb/Ta,
La/ Nb, La/ Ta, Rb/Sr and U/Th ratios. Highly evolved nature of these rocks is also manifested by
irregular REE's pattern that is most visible in late magmatic differentiates with strong hydrothermal or
deuteric alteration represented with K-metasomatism and fluoritization. Positive correlation of uranium
and most of trace and rare earth elements indicate co-mobilization and precipitation of these elements.
Microscopic and scanning electron microscopic studies revealed the presence of uranophane, kasolite,
cotunite, coronadite, galena, fluorite and amazonite.