U-Minerals and Ree Distribution, Paragenesis and Provenance, Um Bogma Formation Southwestern Sinai, Egypt

Abstract

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 sediments are mainly confined and associated with Um Bogma Formation. The stratigraphic sections exposed at the six 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 comprising strike-slip and step faults. These faults commonly trending (NW, NE, N-S and E-W) created a mosaic of faulted blocks within and outside the studied area, which to some degree helped the localization of the Uminerals. The sedimentary rocks of the Um Bogma Formation comprise the sedimentary facies: gibbsite bearing sediments, shales, ferruginous siltstone, marl, dolostone, claystone and (Mn-Fe) ore. These sedimentary facies 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 member of 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 uranyl phosphate (phurcalite) [Ca 2 (UO 2) 3 (PO 4) 2 (OH) 4 ].4H 2 O, was first detected in the study area. The U-minerals association indicated formation under low temperature (<100 o c) oxidizing conditions with pH range 6-7.5 and 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 with contributions from plutonic component. These sediments were deposited in an active continental margin. Environment Lithology Member Formation Age Basaltic sheet or/and sill Triassic Fluviatile Glass sand with siltstone intercalations. ____________ Abu Zarab Lower Carboniferous Swamp Carbonaceous shale withLepidodendron Sp.and Sigillaria Sp.

Magnetic and spectrometric studies of Al-Gor area, Southwestern Sinai, Egypt

“…• Um-Bogma Formation: This formation can be regarded as a poly-mineralized rock unit including (U, Th, Cu, and REEs,) (Alshami, 2018 andAlkhateeb et al, 2019). It can be classified into three members:…”

The Alloga quarry, Southwestern Sinai, Egypt: geological studies, radioactivity and mineralogical investigations

“…The NWtrending faults controlled the high uranium concentration at Wadi Nasieb and Talet Seliem, whereas the NE-trending faults controlled the U-concentrations at Baba. The authors [21] recorded that Allouga and Abu Thor area located within a low basinal-shaped area that was affected by several fault sets comprising strike-slip and step faults, which to some degree helped the localization of the U and Au minerals.…”

Infra-Cambrian Placer Gold-Uraniferous Paleozoic Sediments, Southwestern Sinai, Egypt

“…Weissbrod (1969) gives Um Bogma Formation (8.5-66m) to the carbonat e rocks. Alshami (2017) reported that Um Bogma Formation comprises seven facies, these facies are Fe-Mn ore, gibbsite bearing sediments, claystone, marl, dolostone, shale and ferruginous siltstone. Soliman and Fetouh (1969) subdivided the clastic sediments into El Hashash, Magharet El Maiah and Abu Zarab formations.…”