Geochemical Examination of Surficial Soil Overlying Uranium Deposit in Manyoni, Central Tanzania

  •  Miguta Faustine Ngulimi    
  •  Hiroaki Ishiga    


Geochemical compositions of surface to shallow soil samples of Manyoni uranium deposit in Tanzania were determined by X-ray fluorescence analysis (XRF). Uranium, calcium and chlorine are abundant at the depth of 40 cm to 140 cm. Strong correlations between U, CaO and chlorine suggest uranium and carbonates deposition in a Salt Lake system. Strontium content is higher (370 to 480 ppm) than the average upper continental crust UCC (320 ppm) at the depth of 60 cm to 120 cm suggesting Sr accumulation in carbonates. TiO2 and Fe2O3 abundances appear along the profile but have normal concentrations below the average UCC content. Vanadium is positively correlated to Fe2O3 and Ni (mafic sources) concentrations and negatively correlated to U. Uranium precipitation is suggestive of abrupt evaporation during dry season at Manyoni depositional basin. Chlorine (Cl) with high concentration in the vertical profile may be yielded in the sediments after evaporation of the lake water.

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