Geology of Ore Deposits

, Volume 56, Issue 5, pp 315–321 | Cite as

Fractionation factor of 238U and 235U isotopes in the process of hydrothermal pitchblende formation: A numerical estimate

  • I. V. Chernyshev
  • E. O. DubininaEmail author
  • V. N. Golubev


Owing to the rapid increase in available data on the natural variations of the 238U/235U ratio, new isotopic geochemical mark of redox processes are beginning to emerge. In this connection, numerical estimates of the 238U and 235U fractionation factor (α(UIV−UVI)) accompanying the reduction UVI → UIV are needed. Such an estimate has been obtained for hydrothermal pitchblende formation based on results of high-precision (±0.06‰) measurements of the 238U/235U ratio in local microsamples of coarse spherulitic pitchblende from carbonate-pitchblende veins at the Oktyabr’sky deposit (Strel’tsovsky uranium ore field, eastern Transbaikal region). For this purpose, we used the formation temperature of hydrothermal pitchblende and a maximum estimate of the fractionation factor for 238U and 235U isotopes in the solution-solid phase system under normal (25°C) conditions (Murphy et al., 2014). The most probable isotopic fractionation factor accompanying pitchblende crystallization from hydrothermal solution at T = 320−250°C falls into the interval α(UIV−UVI) = 1.00020−1.00023.


Uranium Fractionation Factor Uranium Deposit 235U Ratio 235U Isotope 
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© Pleiades Publishing, Ltd. 2014

Authors and Affiliations

  • I. V. Chernyshev
    • 1
  • E. O. Dubinina
    • 1
    Email author
  • V. N. Golubev
    • 1
  1. 1.Institute of Geology of Ore Deposits, Petrography, Mineralogy, and GeochemistryRussian Academy of SciencesMoscowRussia

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