Abstract
The 238U/235U ratio was precisely measured in uranium minerals from 11 hydrothermal deposits of different geologic settings and ages situated in ore regions of Asia, Europe, Africa, and North America by MC-ICP-MS using a 233U-236U double spike. The spike was calibrated in reference to the CRM-112A standard with 238U/235U = 137.837 ± 0.015 (Richter et al, 2010). The long-term reproducibility of 238U/235U measurement was estimated as ±0.07‰ by the analysis of monitor samples and the IRMM-3184 standard. The analyses were performed using 0.02–0.04-mg microsamples of uraninite, pitchblende, and coffinite, which were locally extracted from polished sections under an optical microscope. The 238U/235U values obtained for 50 samples of U-bearing minerals range from 137.703 to 137.821, with a 0.86‰ difference and a mean 238U/235U value of 137.773 ± 0.056 (±2SD). The range of 238U/235U variations in seven deposits with uraninite is 0.41‰, which is twice as low as for the deposits with pitchblende-dominated ores. Our study provided the first results for 238U/235U variations in minerals from individual deposits. The largest variations were found in the Oktyabr’skii (Eastern Transbaikalia), Schlema-Alberoda (Erzgebirge), and Shea Creek (Athabasca basin) deposits: 0.70, 0.33, and 0.59‰, respectively. Uranium from the early growth zones of 4–5 mm thick pitchblende spherulitic crusts is isotopically heavier (by 0.22–0.45‰) than uranium from the latest growth zones. A similar isotopic shift in 238U/235U in terms of magnitude (0.31‰) and sense was observed between pitchblende and coffinite overgrowths. The uranium isotopic composition of late pitchblende generations, the products of dissolution and reprecipitation of early phases, is 0.46‰ lighter than that of early pitchblende phases. The character of uranium isotope distribution in pitchblende aggregates is consistent with nuclear-volume-dependent isotope fractionation accompanying U(VI) reduction to U(IV) (Bigeleisen, 1996; Schauble, 2007; Stirling et al., 2007), which causes an enrichment of the U(IV)-bearing solid phase in the heavy isotope 238U. The range of 238U/235U ratios for 11 hydrothermal (high-temperature) deposits (137.703–137.821) lies well within the broader (two-fold) range of values determined for the low-temperature deposits Dybryn in Transbaikalia (Golubev et al., 2013) and Pepegoona in South Australia (Murphy et al., 2014). This can be explained by the fact that the uranium isotopic fractionation associating with U(VI) → U(IV) reduction is accompanied by isotope shifts owing to the long-term interaction of groundwater with early phases within sandstone-type deposits. At the same time, owing to the higher temperatures (by 100–300°C) of formation of hydrothermal deposits compared with sandstone-type deposits, nuclear-volume-dependent uranium isotope fractionation decreases by more than a factor of 2 (Bopp et al., 2009).
Similar content being viewed by others
References
A. O. Nier, “The isotopic composition of uranium and half-lives of the uranium isotopes,” Phys. Rev. 55, 150–153 (1939).
M. Lounsbury, “The natural abundances of the uranium isotopes,” Can. J. Phys. 34, 259–264 (1956).
F. E. Senftle, L. Stieff, F. Cuttitta, and P. K. Kuroda, “Comparison of the isotopic abundances of 235U and 238U and the radium activity ratios in Colorado Plateau uranium ores,” Geochim. Cosmochim. Acta 11(3), 189–193 (1957).
A. N. Hamer and E. J. Robbins, “A search for variations in the natural abundance of uranium-235,” Geochim.Cosmochim. Acta 19(2), 143–145 (1960).
Proceedings of an International Symposium on the Oklo Phenomenon, Libreville, Gabon, West Africa, 1975.
Yu. A. Shukolyukov, Fission Products of Heavy Elements in the Earth (Energoizdat, Moscow, 1982) [in Russian].
G. A. Cowan and H. H. Adler, “The variability of the natural abundances of 235U,” Geochim. Cosmochim. Acta 40(12), 1487–1490 (1976).
R. H. Steiger and E. Jäger, “Subcommission on geochronology: convention on the use of decay constants in geo- and cosmochronology,” Earth Planet. Sci. Lett. 36(3), 359–362 (1977).
A. N. Halliday, D. C. Lee, J. N. Christensen, M. Rehkämper, W. Luo, X. Yi, C. M. Hall, C. J. Ballentine, T. Pettke, and C. Stirling, “Applications of multiple collector-ICP MS to cosmochemistry, geochemistry and paleooceanography,” Geochim. Cosmochim. Acta 62(6), 919–940 (1998).
C. H. Stirling, M. B. Anderson, E.-K. Potter, and A. N. Halliday, “Low-temperature isotopic fractionation of uranium,” Earth Planet. Sci. Lett. 264, 208–225 (2007).
C. H. Stirling, A. N. Halliday, and D. Porcelli, “In search of live 247Cm in the early Solar System,” Geochim. Cosmochim. Acta 69, 1059–1071 (2005).
C. H. Stirling, A. N. Halliday, E.-K. Potter, M. B. Andersen, and B. Zanda, “A low initial abundance of 247Cm in the early Solar System and implications for R-process nucleosynthesis,” Earth Planet. Sci. Lett. 251, 386–397 (2006).
S. Weyer, A. D. Anbar, A. Gerdes, G. W. Gordon, T. J. Algeo, and E. A. Boyle, “Natural fractionation of 238U/235U,” Geochim. Cosmochim. Acta 72(2), 345–359 (2008).
C. J. Bopp, C. C. Lundstrom, T. M. Johnson, and J. J. G. Glessner, “Variations in 238U/235U in uranium ore deposits: isotope signatures of the U reduction process?,” Geology 37, 611–614 (2009).
G. A. Brennecka, L. E. Borg, I. D. Hutcheon, M. A. Sharp, and A. D. Anbar, “Natural variations in uranium isotope ratios of uranium ore concentrates: understanding the 238U/235U fractionation mechanism,” Earth Planet. Sci. Lett. 291(1–4), 228–233 (2010).
G. A. Brennecka, L. E. Wasylenki, J. R. Bargar, S. Weyer, and A. D. Anbar, “Uranium isotope fractionation during adsorption to Mn-oxyhydroxides,” Environ. Sci. Technol. 45, 1370–1375 (2011).
Y. Amelin, A. Kaltenbach, T. Iizuka, C. H. Stirling, T. R. Ireland, M. Petaev, and S. B. Jacobsen, “U-Pb chronology of the Solar System’s oldest solids with variable 238U/235U,” Earth Planet. Sci. Lett. 300, 343–350 (2010).
C. Montoya-Pino, S. Weyer, A. D. Anbar, J. Pross, W. Oschmann, B. van de Schootbrugge, and H. W. Arz, “Global enhancement of ocean anoxia during Oceanic Anoxic Event 2: a quantitative approach using U isotopes,” Geology 38, 315–318 (2010).
A. Bouvier, L. J. Spivak-Birndorf, G. A. Brennecka, and M. Wadhwa, “New constraints on early Solar System chronology from Al-Mg and U-Pb isotope systematics in the unique basaltic achondrite Northwest Africa 2976,” Geochim. Cosmochim. Acta 75, 5310–5323 (2011).
J. Hiess, D. J. Condon, N. McLean, and S. R. Noble, “238U/235U systematics in terrestrial uranium-bearing minerals,” Science 335, 1610–1614 (2012).
B. Kendall, G. A. Brennecka, S. Weyer, and A. D. Anbar, “Uranium isotope fractionation suggests oxidative uranium mobilization at 2.50 Ga original,” Chem. Geol. 362, 105–114 (2013).
S. J. Romaniello, A. D. Herrmann, and A. D. Anbar, “Uranium concentrations and 238U/235U isotope ratios in modern carbonates from the Bahamas: assessing a novel paleoredox proxy,” Chem. Geol. 362, 305–316 (2013).
V. N. Golubev, I. V. Chernyshev, A. V. Chugaev, A. V. Eremina, A. N. Baranova, and V. V. Krupskaya, “U-Pb systems and U isotopic composition of the sandstone-hosted paleovalley Dybryn uranium deposit, Vitim uranium district, Russia,” Geol. Ore Dep., 55(6), 399–410 (2013).
M. J. Murthy, C. H. Stirling, A. Kaltenbach, S. P. Turner, and B. F. Schaefer, “Fractionation of 238U/235U by reduction during low temperature uranium mineralization processes,” Earth Planet. Sci. Lett. 388, 306–317 (2014).
I. V. Chernyshev, A. N. Baranova, V. N. Golubev, and A. V. Chugaev, “Isotope composition of natural uranium,” in Proceedings of 5th Russian Conference on Isotope Geochronology “Geochronometer Isotope Systems, Methods of Their Study, and Chronology of Geological Processes, Moscow, Russia, 2012” (IGEM, Moscow, 2012), pp. 361–363 [in Russian].
I. V. Chernyshev, V. N. Golubev, A. V. Chugaev, and A. N. Baranova, “238U/235U variations in high- and low-temperature uranium deposits,” in Abstracts of Goldschmidt Conference, Florence, Italy, 2013 (Florence, 2013), p. 871.
I. V. Chernyshev and V. N. Golubev, “The Strel’tsovskoe Deposit, eastern Transbaikalia: isotope dating of mineralization in Russia’s largest uranium deposit,” Geochem. Int. 34(10), 834–846 (1996).
V. N. Golubev, L. B. Makar’ev, and L. V. Bylinskaya, “Deposition and remobilization of uranium in the Northern Baikal region: evidence from the U-Pb isotopic systems of uranium ores,” Geol. Ore Dep. 55(6), 482–490 (2008).
Uranium and Molybdenum-Uranium Deposits in the Regions of Continental Magmatism: Geology and Geodynamic Conditions of Formation (IFZ RAN. IGEM RAN, Moscow, 2012) [in Russian].
V. N. Golubev, “Age of dispersed uranium mineralization in rocks of the framework of the Strel’tsovka uranium ore field and the Yamsky Site, Eastern Transbaikal Region,” Geol. Ore Dep. 53(5), 401–411 (2011).
A. Baksheev, V. N. Golubev, V. Yu. Prokof’ev, M. F. Vigasina, V. O. Yapaskurt, and I. A. Bryzgalov, “Tourmaline from quartz lenses of the Urtui granite pluton, Strel’tsovka orefield, Transbaikal Krai,” Moscow Univ. Geol. Bull. 67(1), 18–29 (2012).
N. P. Laverov and I. V. Chernyshev, “Temporal relation of uranium deposits with continental volcanism,” in Geochronology and Problems of Ore Formation (Nauka, Moscow, 1977), pp. 5–18 [in Russian].
Conditions of Formation of Uranium Deposits in Volcanic Depressions (Atomizdat, Moscow, 1972) [in Russian].
B. P. Vlasov, L. V. Matyushin, and G. B. Naumov, “Schlema-Alberoda vein uranium deposit, Erzgebirge,” Geol. Rudn. Mestorozhd., No. 3, 205–221 (1993).
E. Harlass and H. Schutzel, “Zur paragenetischen Stellung der Uranpechblende in den hydrotermalen Lagerstatten des westlichen Erzgebirges,” Z. Angew. Geologie 11(11), 569–582 (1965).
W. Schuppan, W. Büder, and G. Lange, “On uranium mineralisation in the vein deposits of the Western Erzgebirge, Germany,” Monograph Ser. Miner. Dep. 31, 191–207 (1994).
Yu. M. Dymkov, Uranium Mineralization in the Erzgebirge (Atomizdat, Moscow, 1960) [in Russian].
I. V. Chernyshev, V. N. Golubev, V. A. Troitskii, A. A. Agapova, M. V. Tsvetkova, and N. K. Shcherbinina, “Isochron considerations and sampling localities,” in Mass-Spectrometry and Isotope Geology (Nauka, Moscow, 1983), pp. 90–108 [in Russian].
V. N. Golubev, M. Cuney, and B. Poty, “Phase composition and U-Pb pitchblende systems of quartz-calcite-pitchblende veins at the Schlema-Alberoda Deposit (Erzgebirge),” Geol. Ore Dep. 42(6), 461–473 (2000).
T. L. Krylova, V. I. Velitchkin, and A. V. Timofeev, “The mineral-forming fluids at the vein-type uranium deposits of the Saxonian Erzgebirge (Germany),” in International Conference on Uranium Geochemistry, Nancy, France, 2003 (Nancy, 2003), pp. 33–36.
M. M. Konstantinov and E. Ya. Kulikova, Uranium Provinces (Atomizdat, Moscow, 1960) [in Russian].
D. Derome, M. Cathelineau, M. Cuney, C. Fabre, T. Lhomme, and D. A. Banks, “Mixing of sodic and calcic brines and uranium deposition at McArthur River, Saskatchewan, Canada: a Raman and laser-induced breakdown spectroscopic study of fluid inclusions,” Econ. Geol. 100, 1529–1545 (2005).
S. Richter, R. Eykens, H. Kühn, Y. Aregbe, A. Verbruggen, and S. Weyer, “New average values for the n(238U)/n(235U) isotope ratios of natural uranium standards,” Int. J. Mass Spectrom. 295, 94–97 (2010).
I. V. Chernyshev, V. N. Golubev, A. V. Chugaev, and A. N. Baranova, “238U and 235U isotope fractionation under water-U-bearing rock interaction” in Abstracts of Goldschmidt Conference, Sacramento, US, 2014 (Sacramento, 2014), p. 462.
D. J. Condon, N. McLean, S. R. Noble, and S. A. Bowring, “Isotopic composition (238U/235U) of some commonly used uranium reference materials,” Geochim. Cosmochim. Acta 74(24), 7127–7143 (2010).
K. Mathew, P. Mason, A. Voeks, and U. Narayanan, “Uranium isotope abundance ratios in natural uranium metal certified reference material 112-A,” Int. J. Mass Spectrom. 315, 8–14 (2012).
E. A. Schauble, “Role of nuclear volume in driving equilibrium stable isotope fractionation of mercury, thallium, and other very heavy elements,” Geochim. Cosmochim. Acta 71, 2170–2189 (2007).
A. Basu, R. A. Sanford, T. M. Johnson, C. C. Lundstrom, and F. E. Löffler, “Uranium isotopic fractionation factors during U(VI) reduction by bacterial isolates,” Geochim. Cosmochim. Acta (in press).
J. Bigeleisen, “Nuclear size and shape effects in chemical reactions. Isotope chemistry of heavy elements,” J. Am. Chem. Soc. 118, 3676–3680 (1996).
E. A. Schauble, M. Meheut, and P. S. Hill, “Combining metal stable isotope fractionation theory with experiments,” Elements 5(6), 369–374 (2009).
M. Cuney and K. Kyser, “Recent and not-so-recent developments in uranium deposits and implications for exploration,” Short Course Ser. 39 (2008).
G. B. Naumov, Principles of the Physicochemical Model of Uranium Ore Formation (Atomizdat, Moscow, 1978) [in Russian].
R. P. Rafal’sky, Hydrothermal Equilibria and Mineral Formation (Atomizdat, Moscow, 1973) [in Russian].
S. B. Romberger, “Transport and deposition of uranium in hydrothermal systems at temperatures up to 300°C, with genetic implications,” in Geology of Uranium Deposits, Can. Inst. Mining Metall. 32, 12–17 (1984).
H. Freymuth, M. Andersen, and T. Elliott, “Mass-related U isotope fractionation during alteration of oceanic crust and release of U in subduction zones-implications for deep recycling of oceanic crust,” in Abstracts of Goldschmidt Conference, Florence, 2013 (Florence, 2013), p. 1112.
Author information
Authors and Affiliations
Corresponding author
Additional information
Original Russian Text © I.V. Chernyshev, V.N. Golubev, A.V. Chugaev, A.N. Baranova, 2014, published in Geokhimiya, 2014, No. 12, pp. 1059–1078.
Rights and permissions
About this article
Cite this article
Chernyshev, I.V., Golubev, V.N., Chugaev, A.V. et al. 238U/235U isotope ratio variations in minerals from hydrothermal uranium deposits. Geochem. Int. 52, 1013–1029 (2014). https://doi.org/10.1134/S0016702914120027
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S0016702914120027