Notes On The Migration Of Uranium

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lateritization process leads to the migration of uranium, but the produced laterites of either grey (Al) or brown (Fe) soils are good adsorbents for uranium and other heavy metals. The karstification process leads to the formation of caves which are filled by either allochtonous or autochtonous soils. These karst soils host uranium and rare earth elements (El Aassy et al., 2006).
(2) Middle Marly Dolostone-Siltstone Member is also karstified and lateritized and consists of marl with siltstone and gibbsite-bearing siltstone (Fig. 5a). Its thickness is 6–9 m and it is moderately radioactive.
(3) Upper Dolostone Member unconformably overlies the karstified and lateritized middle member and consists of bedded dolostone with thin shale interbeds (Fig. 5b).
The dolostone beds are present as step-like forms and in some parts are not deposited and laterally vary to grey claystone. The dark grey claystone as noticed in the
Allouga, Abu Zarab and Abu Hamata localities is enriched in elemental sulphur as an oxidation product of pyrite and

chalcopyrite. Its thickness is 3–4 m and the dolostone has low radioactivity, while the dark grey claystone is moderately radioactive. Visible secondary uranium mineralizations are observed associated with the Um
Bogma Formation in siltstone, shale, clay, and gravel.
The El Hashash Formation disconformably overlies the
Um Bogma Formation and consists of sandstone with thin siltstone at
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