and   activity ratios in mineral phases of a lateritic weathered zone

Lowson, Richard T.; Short, S.A.; Davey, B. G.; Gray, D.

doi:10.1016/0016-7037(86)90131-6

Cited by 56 publications

(32 citation statements)

References 15 publications

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“…6(b) and (c)). Lowson et al (1986) studied the ARs of the samples from lateritic weathered uranium ore body in Alligator Rivers region, Australia, and showed the similarity of ARs in the ground water and amorphous iron phase, and ARs higher than 1 in clay/quartz resistate phase. The latter result is rather different from that in this study.…”

Section: Resultsmentioning

confidence: 99%

Uranium distribution and 234U/238U activity ratios in a sedimentary bauxite deposit, from Yangwa mine, China, and its implication for sedimentation process.

Kanai

1992

Geochem. J.

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Concentrationsof uranium and other elements in bauxite deposit from Yangwa mine at Jiaozuo area in Henan Province, China, were determined, and geochemical behavior of 234U and sedimentation process were studied by leaching experiments.An inverse correlation between two major components, A1203 and Fe203, was observed. A1203 has a distinct correlation with Ti, Cr, U and V, while Fe203 correlated with Mn, Ca and Cu. Cr, V and U were enriched in the deposit compared with crustal abundance, while Si02, MnO, MgO, CaO, Na20, Cu, Sr and Ba were depleted. In phase extraction experiments, the Fe, Mn, Mg, Ca, and Sr were predominantly in the "HC1 soluble fraction".With one exception, most of the U in the bauxite was in the "HF soluble fraction" ( 60%), and -r 30% of the U was in the "resistate fraction" . The 234U/238U activity ratios in these fractions were less than unity, and have a good correlation with the fractional U content. This relation suggests that 234U was leached out from the surface of the U-containing mineral grains. In comparison, the activity ratios of HCl soluble U were more than unity, and are inversely correlated with the fractional U contents. This suggests that an almost constant amount of mobile 234U was present in the deposits.The principal bauxite ore body could be thought to be sedimentary in origin: A terra rossa was formed on the karstic Ordovician limestone. It was rich in Fe203, which suggests relatively oxidative sedimentary condition. The clay minerals, fine-grained materials originated from Pre-Cambrian base ment were then transported and deposited repeatedly on the terra rossa. The deposition of the clay minerals changed the sink from oxidative to reducing condition, favoring for the deposition of U. The original clay minerals in the bauxite deposit were kaolinite and gibbsite. As the reversible change from kaolinite to gibbsite depends on the H4SiO4 concentration, the alteration degree of gibbsite might have been controlled by the movement of H4Si04. 234U was estimated to have been ejected from the surface of U-containing minerals and migrated through the ore deposits, then adsorbed by iron hydroxides at the bottom of the ore body.

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Section: Resultsmentioning

confidence: 99%

Uranium distribution and 234U/238U activity ratios in a sedimentary bauxite deposit, from Yangwa mine, China, and its implication for sedimentation process.

Kanai

1992

Geochem. J.

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“…This is not correct and need not be invoked. Magnetite is now clearly known to form in situ in many soils (Smirnov 1978;Lowson et al 1986;Maher & Taylor 1988;Machel & Burton 1992). Particularly relevantly, Hart & Fuller (1988) found this happened as a late stage of weathering of dolomite.…”

Section: Resistant Mineralsmentioning

confidence: 99%

The elemental content of Niue Island soils as an indicator of their origin

Whitehead

Hunt

Leslie

et al. 1993

New Zealand Journal of Geology and Geophysics

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The major and trace element contents of 241 Niue Island lateritic soils were determined, mainly by X-ray fluorescence, to deduce soil origins. The analyses showed very low SiO 2 content, and a high content of Mg, P, V, Cr, Sr, Y, Hg, and α-counts, compared with other laterites worldwide. The distribution patterns are consistent with derivation by weathering from calcite and dolomite rather than from deposited volcanic ash. Weathering is a particularly novel explanation for the origin of the relatively high content of P in these soils. The soils contain a negative Ce anomaly, consistent with an origin from seawater or coral, but not volcanic ash. If recent results showing in situ formation of magnetite in soils are applicable, the soil mineralogy is wholly consistent with an origin from calcite/dolomite. An origin from calcite is also consistent with the relative lack of volcanic ash on the seabed nearby, and very low deposition of aeolian dust. The radioactivity content is consistent neither with calcite/dolomite weathering, nor volcanic ash origin, but may have originated, like a few of the stable elements, from rising hydrothermal solutions.

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“…In recent years, the methods based on radioactive disequilibria have been applied to the study of different geological processes during the recent Quaternary, such as sedimentation in marine and continental environments (Legeleux et al, 1994;Burnett and Veeh, 1992), soil formation and evolution (Mathieu et al, 1995;Lowson et al, 1986), groundwater dynamics (Lievert et al, 1994;Ivanovich et al, 1991), and magma genesis (Macdougall, 1995;Heath et al, 1998;Condomines et al, 1988Condomines et al, , 1995Chabaux and Allegre, 1994;Asmeron and Edwards, 1995). Furthermore, geochronological methods based on radioactive disequilibria have been applied in dating sedimentary and volcanic rocks younger than 300,000 years Condomines et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

“…For natural uranium, the 235 U/ 238 U activity ratio has a constant value of 0.046, while the 234 U/ 238 U activity ratio is variable. The variation in the 234 U/ 238 U ratio is due to natural causes in many waters (Riotte and Chabaux, 1999;Plater et al, 1992), soil (Lowson and Short, 1988;Lowson et al, 1986;Hansen and Stout, 1968;Stuckless et al, 1977;Rosholt et al, 1966), sediment and uranium ores of different geographical origin (Richter et al, 1999). The mechanism of such variation is preferential leaching of 234 U compared with 238 U from the solid phase, caused by radiation damage of the crystal lattice upon alpha decay of 238 U, oxidation of insoluble tetravalent 234 U to soluble hexavalent 234 U during decay, and alpha recoil of 234 Th (and its daughter 234 U) into the solution phase.…”

Section: Introductionmentioning

confidence: 99%

Variation in the uranium isotopic ratios²³⁴U/²³⁸U,²³⁸U/total-U and²³⁴U/total-U in Indian soil samples: Application to environmental monitoring

et al. 2012

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The uranium isotopes 238 U, 235 U and 234 U are found naturally in the environment.238 U and 235 U are parent nuclides of two independent decay series of isotopes, while 234 U is a member of the 238 U decay chain. When decay series occur in a closed system the series tends to reach, with time, the state of secular equilibrium in which the activities of all series members are equal to the activity of its first nuclide. The activity ratio 234 U/ 238 U in natural uranium may vary as a consequence of decay chain disequilibrium due to alpha recoil and biogeochemical processes. A study based on measurement of uranium concentration and 234 U/ 238 U activity ratios in soil samples collected from Nalgonda district, Andhra Pradesh, India, a proposed mining site, was carried out to find the spatial distribution of uranium and the state of secular equilibrium of 234 U/ 238 U to examine the possibility of applying uranium concentration and uranium isotopic activity ratios to detect any hydrogeochemical changes in the environment during/post-operation. Soil samples were collected and analyzed for uranium concentration using the conventional UV fluorimetric method, showing a uranium concentration in the range of 0.7 ± 0.2 ppm to 7.9 ± 0.4 ppm with an average of 3.4 ppm, and 234 U/ 238 U activity ratios were estimated using the alpha spectrometry technique, showing an activity ratio in the range of 0.92 ± 0.11 to 1.02 ± 0.11. The 234 U/ 238 U activity ratio obtained indicated that these two uranium isotopes are in the state of secular radioactive equilibrium. The percent activity ratio of 238 U/total U and 234 U /total U is observed to vary from 47.94 ± 4.83 to 50.76 ± 4.87 and 45.80 ± 3.83 to 49.14 ± 3.99, respectively.

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and activity ratios in mineral phases of a lateritic weathered zone

Cited by 56 publications

References 15 publications

Uranium distribution and 234U/238U activity ratios in a sedimentary bauxite deposit, from Yangwa mine, China, and its implication for sedimentation process.

Uranium distribution and 234U/238U activity ratios in a sedimentary bauxite deposit, from Yangwa mine, China, and its implication for sedimentation process.

The elemental content of Niue Island soils as an indicator of their origin

Variation in the uranium isotopic ratios²³⁴U/²³⁸U,²³⁸U/total-U and²³⁴U/total-U in Indian soil samples: Application to environmental monitoring

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and activity ratios in mineral phases of a lateritic weathered zone

Cited by 56 publications

References 15 publications

Uranium distribution and 234U/238U activity ratios in a sedimentary bauxite deposit, from Yangwa mine, China, and its implication for sedimentation process.

Uranium distribution and 234U/238U activity ratios in a sedimentary bauxite deposit, from Yangwa mine, China, and its implication for sedimentation process.

The elemental content of Niue Island soils as an indicator of their origin

Variation in the uranium isotopic ratios234U/238U,238U/total-U and234U/total-U in Indian soil samples: Application to environmental monitoring

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Product

Resources

About

Variation in the uranium isotopic ratios²³⁴U/²³⁸U,²³⁸U/total-U and²³⁴U/total-U in Indian soil samples: Application to environmental monitoring