The studied dyke is a famous U-bearing microgranite dyke located in Wadi Um Doweila that extends
for10.6 km in the northeast direction. The dyke and its surrounding metavolcanics are suffering from a
series of sub-parallel faults trending NW. The dyke is mainly of granitic composition characterized by
grayish pink color where the potash feldspar is the main feldspar. It is fine-grained rock with obvious
porphyritic texture and it is dominated by zircon, apatite, monazite and fluorite as the main accessory
minerals beside uranophane as the main uranium mineral.
The geochemistry of the dyke shows that it originated from calc-alkaline magma type, which developed
a postorogenic and within plate tectonic setting. The distribution and contents of U, Th and Zr suggest
that they are controlled by the fractional crystallization of small amount of accessory minerals due to the
incompatible behavior. The study of the metasomatized parts of the dyke indicated that most of the Th and
50% U are found in the accessory minerals. The remainder of U is deposited in the inter-granular spaces
and in the newly formed hydrothermal minerals such as as sericite and Fe- oxides. Such U accumulations
at labile sites probably constitute the potential source of U which leached,- mobilized and redeposited by
the convicting hydrothermal fluids along the faults and probably led to the formation of the secondary
uranophane mineralization in the central and southern parts of the dyke. The uranium concentrations
appear to be structurally controlled.