The lower Carboniferous sediments at SW Sinai comprises four stratigraghic formations from bottom:Um Bogma, El Hashash, Magharet El Maiah and Abu Zarab formations. The uranium bearing sedimentsare mainly confined and associated with Um Bogma Formation. The stratigraphic sections exposed at thesix localities, (Talet Selim, Nasib, Abu Thor, Allouga, Abu Hamata and El Sahu), were studied in detail.These are exposed within a low basinal shaped area that was affected by several fault sets comprisingstrike-slip and step faults. These faults commonly trending (NW, NE, N-S and E-W) created a mosaic offaulted blocks within and outside the studied area, which to some degree helped the localization of the U-minerals.The sedimentary rocks of the Um Bogma Formation comprise the sedimentary facies: gibbsite bearingsediments, shales, ferruginous siltstone, marl, dolostone, claystone and (Mn-Fe) ore. These sedimentaryfacies are well developed in the central parts of the studied area (Allouga and Abu Thor). The siltstone,shale and claystone are the main sedimentary facies hosting the U-minerals especially in the lower memberof Um Bogma Formation.The U-minerals found within these facies comprise U-oxides, U-silicates, and Uranyl-Oxyhydroxides, -silicates, -phosphates, arsenates, -vanadate-, -molybadate-, -carbonates and-sulphate complexes. The uranylphosphate (phurcalite) [Ca2(UO2)3(PO4)2(OH)4].4H2O, was first detected in the study area. The U-mineralsassociation indicated formation under low temperature (<100oc) oxidizing conditions with pH range 6-7.5and high evaporation rate for the precipitation of the uranyl sulphate complexes.The REE patterns of the above sedimentary facies suggest a provenance of recycled old sediments withcontributions from plutonic component. These sediments were deposited in an active continental margin.