Jump to ContentJump to Main Navigation
Show Summary Details
More options …

American Mineralogist

Journal of Earth and Planetary Materials

Ed. by Baker, Don / Xu, Hongwu / Swainson, Ian


IMPACT FACTOR 2018: 2.631

CiteScore 2018: 2.55

SCImago Journal Rank (SJR) 2018: 1.355
Source Normalized Impact per Paper (SNIP) 2018: 1.103

Online
ISSN
1945-3027
See all formats and pricing
More options …
Volume 101, Issue 6

Issues

Uraninite from the Olympic Dam IOCG-U-Ag deposit: linking textural and compositional variation to temporal evolution

Edeltraud Macmillan
  • Corresponding author
  • School of Physical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
  • BHP Billiton Olympic Dam, Adelaide, South Australia 5000, Australia
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Nigel J. Cook
  • School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Kathy Ehrig / Cristiana L. Ciobanu
  • School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Allan Pring
  • School of Chemical and Physical Sciences, Flinders University, Bedford Park, South Australia 5042, Australia
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2016-06-03 | DOI: https://doi.org/10.2138/am-2016-5411

Abstract

The Olympic Dam IOCG-U-Ag deposit, South Australia, the world’s largest known uranium (U) resource, contains three main U-minerals: uraninite, coffinite, and brannerite. Four main classes of uraninite have been identified. Uraninite occurring as single grains is characterized by high-Pb and ΣREE+Y (ΣREY) but based on textures can be classified into three of these classes, typically present in the same sample. Primary uraninite (Class 1) is smallest (10–50 mm), displays a cubic-euhedral habit, and both oscillatory and sectorial zoning. “Zoned” uraninite (Class 2) is coarser, sub-euhedral, and combines different styles of zonation in the same grain. “Cobweb” uraninite (Class 3) is coarser still, up to several hundred micrometers, has variable hexagonal-octagonal morphologies, varying degrees of rounding, and features rhythmic intergrowths with sulfide minerals. In contrast, the highest-grade U in the deposit is found as micrometer-sized grains to aphanitic varieties of uraninite that form larger aggregates (up to millimeter) and vein-fillings (massive, Class 4) and have lower Pb and ΣREY, but higher Ca.

Nanoscale characterization of primary and cobweb uraninite shows these have defect-free fluorite structure. Both contain lattice-bound Pb+ΣREY, which for primary uraninite is concentrated within zones, and for cobweb uraninite is within high-Pb+ΣREY domains. Micro-fractured low-Pb+ΣREY domains, sometimes with different crystal orientation to the high-Pb+ΣREY domains in the same cobweb grain, contain nanoscale inclusions of galena, Cu-Fe-sulfides, and REY-minerals. The observed Pb zonation and presence of inclusions indicates solid-state trace-element mobility during the healing of radiogenic damage, and subsequent inclusion-nucleation + recrystallization during fS2-driven percolation of Cu-bearing fluid.

Tetravalent, lattice-bound radiogenic Pb is proposed based on analogous evidence for U-bearing zircon. Calculating the crystal chemical formula to UO2 stoichiometry, the sum of cations (M*) is ~1 for most classes, but the presence of mono-, di-, and trivalent elements (ΣREY, Ca, etc.) drive stoichiometry toward hypostoichiometric M*O2–x. In the absence of measured O and constraints of hypostoichiometric fluorite-structure, charge-balance calculations showing O deficit in the range 0.15–0.36 apfu is compensated by assumption of mixed U oxidation states. Crystal structural formulas show up to 0.20 apfu Pb and 0.25 apfu ΣREY in Classes 1–3, while for Class 4, these are an order of magnitude less. Low-Pb and ΣREY subcategories of Classes 2 and 3 are similar to massive uraninite with ~0.2 apfu Ca. Other elements (Si, Na, Mn, As, Nb, etc.), show two distinct geochemical trends: (1) across Classes 1–3; and (2) Class 4, whereby low-Pb+ΣREY sub-populations of Classes 2 and 3 are part of trend 2 for certain elements. Plots of alteration factor (CaO+SiO2+Fe2O3) vs. Pb/U suggest two uraninite generations: early (high-Pb+ΣREY, Classes 1–3); and late (massive, Class 4). There is evidence of Pb loss from diffusion, leaching and/or recrystallization for Classes 2–3 (low-Pb+ΣREY domains).

Micro-analytical data and petrographic observations reported here, including nanoscale characterization of individual uraninite grains, support the hypothesis for at least two main uraninite mineralizing events at Olympic Dam and multiple stages of U dissolution and reprecipitation. Early crystalline uraninite is only sparsely preserved, with the majority of uraninite represented by the massive-aphanitic products of post-1590 Ma dissolution, reprecipitation, and possibly addition of uranium into the system. Coupled dissolution-reprecipitation reactions are suggested for early uraninite evolution across Classes 1 to 3. The calculated oxidation state [U6+/(U4++U6+)] of the “early” and “late” populations point to different conditions at the time of formation (charge compensation for ΣREY-rich early fluids) rather than auto-oxidation of uraninite. Late uraninites may have formed hydrothermally at lower temperatures (T < 250 °C).

Key words: Uranium; uraninite; Olympic Dam; IOCG deposits

Special collection papers can be found online at http://www.minsocam.org/MSA/AmMin/special-collections.html.

References cited

  • Alexandre, P., and Kyser, T.K. (2005) Effects of cationic substitutions and alteration in uraninite, and implications for the dating of uranium deposits. Canadian Mineralogist, 43, 1005–1017.Google Scholar

  • Allen, G.C., and Holmes, N.R. (1995) A mechanism for the UO2 to a-U3O8 phase transformation. Journal of Nuclear Materials, 223, 231–237.Google Scholar

  • Andersson, D.A., Baldinozzi, G., Desgranges, L., Conradson, D.R., and Conradson, S.D. (2013) Density functional theory calculations of UO2 oxidation: Evolution of UO2+x, U4O9–y, U3O7, and U3O8. Inorganic Chemistry, 52, 2769–2778.Google Scholar

  • Bourdon, B., Henderson, G.M., Lundstrom, C.C., and Turner, S.P. (2003) Introduction to U-series geochemistry. In B. Bourdon, G.M. Henderson, C.C. Lundstrom, and S.P. Turner, Eds., Uranium-Series Geochemistry, 52, p. 1–21. Reviews in Mineralogy and Geochemistry, Mineralogical Society of America, Chantilly, Virginia.Google Scholar

  • Bowles, J.F.W. (1990) Age dating of individual grains of uraninite in rocks from electron microprobe analyses. Chemical Geology, 83, 47–53.Google Scholar

  • Ciobanu, C.L., Cook, N.J., Utsunomiya, S., Pring, A., and Green, L. (2011) Focussed ion beam-transmission electron microscopy applications in ore mineralogy: Bridging micro- and nanoscale observations. Ore Geology Reviews, 42, 6–31.Google Scholar

  • Ciobanu, C.L., Wade, B.P., Cook, N.J., Schmidt Mumm, A., and Giles, D. (2013) Uranium-bearing hematite from the Olympic Dam Cu-U-Au deposit, South Australia: A geochemical tracer and reconnaissance Pb-Pb geochronometer. Precambrian Research, 238, 129–147.Google Scholar

  • Creaser, R.A., and Cooper, J.A. (1993) U-Pb geochronology of middle Proterozoic felsic magmatism surrounding the Olympic Dam Cu-U-Au-Ag and Moonta Cu-Au-Ag deposits, South Australia. Economic Geology, 88, 186–197.Google Scholar

  • Deditius, A.P., Utsunomiya, S., and Ewing, R.C. (2007) Fate of trace elements during alteration of uraninite in a hydrothermal vein-type U-deposit from Marshall Pass, Colorado, USA. Geochimica et Cosmochimica Acta, 71, 4954–4973.Google Scholar

  • Deditius, A.P., Utsunomiya, S., Wall, M.A., Pointeau, V., and Ewing, R.C. (2009) Crystal chemistry and radiation-induced amorphization of P-coffinite from the natural fission reactor at Bangombé, Gabon. American Mineralogist, 94, 827–837.Google Scholar

  • Depiné, M., Frimmel, H.E., Emsbo, P., Koenig, A.E., and Kern, M. (2013) Trace element distribution in uraninite from Mesoarchaean Witwatersrand conglomerates (South Africa) supports placer model and magmatogenic source. Mineralium Deposita, 48, 423–435.Google Scholar

  • Desgranges, L., Baldinozzi, G., Rousseau, G., Nièpce, J.-C., and Calvarin, G. (2009) Neutron diffraction study of the in situ oxidation of UO2. Inorganic Chemistry, 48, 7585–7592.Google Scholar

  • Donovan, J.J. (2014) Probe for EPMA: Acquistion, Automation and Analysis. Ver. 10.3.5 Xtreme Edition. Probe Software, Inc., Oregon, U.S.A.Google Scholar

  • Ehrig, K., McPhie, J., and Kamenetsky, V. (2012) Geology and mineralogical zonation of the Olympic Dam iron oxide Cu-U-Au-Ag deposit, South Australia. In J.W. Hedenquist, M. Harris, and F. Camus, Eds., Geology and Genesis of Major Copper Deposits and Districts of the World: A Tribute to Richard H. Sillitoe, Special Publication 16, p. 237–267. Society of Economic Geologists, Littleton, Colorado.Google Scholar

  • Evins, L.Z., Jensen, K.A., and Ewing, R.C. (2005) Uraninite recrystallization and Pb loss in the Oklo and Bangombé natural fission reactors, Gabon. Geochimica et Cosmochimica Acta, 69, 1589–1606.Google Scholar

  • Fayek, M., and Kyser, T.K. (1997) Characterization of multiple fluid-flow events and rare-earth-element mobility associated with formation of unconformity-type uranium deposits in the Athabasca Basin, Saskatchewan. Canadian Mineralogist, 35, 627–658.Google Scholar

  • Fayek, M., Janeczek, J., and Ewing, R.C. (1997) Mineral chemistry and oxygen isotopic analyses of uraninite, pitchblende and uranium alteration minerals from the Cigar Lake Deposit, Saskatchewan, Canada. Applied Geochemistry, 12, 549–565.Google Scholar

  • Fayek, M., Burns, P., Guo, Y.X., and Ewing, R.C. (2000) Micro-structures associated with uraninite alteration. Journal of Nuclear Materials, 277, 204–210.Google Scholar

  • Finch, R.J., and Murakami, T. (1999) Systematics and paragenesis of uranium minerals. In P.C. Burns and R.J. Finch, Eds., Uranium: Mineralogy, Geochemistry and the Environment, 38, p. 91–179. Reviews in Mineralogy and Geochemistry, Mineralogical Society of America, Chantilly, Virginia.Google Scholar

  • Flint, R.B., Blissett, A.H., Conor, C.H., Cowley, W.M., Cross, K.C., Creaser, R.A., Daly, S.J., Krieg, G.W., Major, R.B., Teale, G.S., and Parker, A.J. (1993) Mesoproterozoic. In J.F. Drexel, W.V. Preiss, and A.J. Parker, Eds., The Geology of South Australia: The Precambrian, 1, Bulletin 54, 106–169. Geological Survey of South Australia, Adelaide.Google Scholar

  • Foden, J., Elburg, M., Dougherty-Page, J., and Burtt, A. (2006) The timing and duration of the Delamerian Orogeny: Correlation with the Ross Orogen and implications for Gondwana assembly. The Journal of Geology, 114, 189–210.Google Scholar

  • Förster, H.J. (1999) The chemical composition of uraninite in Variscan granites of the Erzgebirge, Germany. Mineral Magazine, 63, 239–252.Google Scholar

  • Frimmel, H.E., Schedel, S., and Brätz, H. (2014) Uraninite chemistry as forensic tool for provenance analysis. Applied Geochemistry, 48, 104–121.Google Scholar

  • Frondel, C. (1958) Systematic mineralogy of uranium and thorium. U.S. Geological Survey Bulletin 1064.

  • Fryer, B.J., and Taylor, R.P. (1987) Rare-earth element distributions in uraninites: Implications for ore genesis. Chemical Geology, 63, 101–108.Google Scholar

  • Gauthier-Lafaye, F., Holliger, P., and Blanc, P.-L. (1996) Natural fission reactors in the Franceville basin, Gabon: A review of the conditions and results of a “critical event” in a geologic system. Geochimica et Cosmochimica Acta, 60, 4831–4852.Google Scholar

  • Goemann, K. (2012) Mineral analysis by EPMA. AMAS12 EPMA workshop presentation notes, 6–14. Australian Microbeam Analysis Society, Sydney.Google Scholar

  • Haynes, D.W., Cross, K.C., Bills, R.T., and Reed, M.H. (1995) Olympic Dam ore genesis: A fluid-mixing model. Economic Geology, 90, 281–307.Google Scholar

  • Hazen, R.M., Ewing, R.C., and Sverjensky, D.A. (2009) Evolution of uranium and thorium minerals. American Mineralogist, 94, 1293–1311.Google Scholar

  • Hidaka, H., Holliger, P., Shimizu, H., and Masuda, A. (1992) Lanthanide tetrad effect observed in the Oklo and ordinary uraninites and its implication for their forming processes. Geochemical Journal, 26, 337–346.Google Scholar

  • Hitzman, M.W., Oreskes, N., and Einaudi, M.T. (1992) Geological characteristics and tectonic setting of proterozoic iron oxide (Cu-U-Au-REE) deposits. Precambrian Research, 58, 241–287.Google Scholar

  • Janeczek, J., and Ewing, R.C. (1991) X-ray powder diffraction study of annealed uraninite. Journal of Nuclear Materials, 185, 66–77.Google Scholar

  • Janeczek, J., and Ewing, R.C. (1992a) Dissolution and alteration of uraninite under reducing conditions. Journal of Nuclear Materials, 190, 157–173.Google Scholar

  • Janeczek, J., and Ewing, R.C. (1992b)Structural formula of uraninite. Journal of Nuclear Materials, 190, 128–132.Google Scholar

  • Janeczek, J., and Ewing, R.C. (1995) Mechanisms of lead release from uraninite in the natural fission reactors in Gabon. Geochimica et Cosmochimica Acta, 59, 1917–1931.Google Scholar

  • Janeczek, J., Ewing, R.C., Oversby, V.M., and Werme, L.O. (1996) Uraninite and UO2 in spent nuclear fuel: a comparison. Journal of Nuclear Materials, 238, 121–130.Google Scholar

  • Johnson, J.P. (1993) The geochronology and radiogenic isotope systematics of the Olympic Dam copper-uranium-gold-silver deposit, South Australia. Unpublished Ph.D. thesis, The Australian National University, Canberra.Google Scholar

  • Johnson, J.P., and Cross, K.C. (1995) U-Pb geochronological constraints on the genesis of the Olympic Dam Cu-U-Au-Ag deposit, South Australia. Economic Geology, 90, 1046–1063.Google Scholar

  • Kotzer, T.G., and Kyser, T.K. (1993) O, U, and Pb isotopic and chemical variations in uraninite: Implications for determining the temporal and fluid history of ancient terrains. American Mineralogist, 78, 1262–1274.Google Scholar

  • Kramers, J., Frei, R., Newville, M., Kober, B., and Villa, I. (2009) On the valency state of radiogenic lead in zircon and its consequences. Chemical Geology, 261, 4–11.Google Scholar

  • Krneta, S., Ciobanu, C.L., Cook, N.J., Ehrig, K., and Kamenetsky, V.S. (2015) Apatite in the Olympic Dam Fe-oxide Cu-U-Au-Ag deposit. In Proceedings for Mineral Resources in a Sustainable World, 3, p. 1103–1106. 13th Biennial SGA Meeting, Nancy, France, August 2015.Google Scholar

  • Leroy, J.L., and Turpin, L. (1988) REE, Th and U behaviour during hydrothermal and supergene processes in a granitic environment. Chemical Geology, 68, 239–251.Google Scholar

  • McPhie, J., Kamenetsky, V.S., Chambefort, I., Ehrig, K., and Green, N. (2011) Origin of the supergiant Olympic Dam Cu-U-Au-Ag deposit, South Australia: Was a sedimentary basin involved? Geology, 39, 795–798.Google Scholar

  • Mercadier, J., Cuney, M., Lach, P., Boiron, M.-C., Bonhoure, J., Richard, A., Leisen, M., and Kister, P. (2011) Origin of uranium deposits revealed by their rare earth element signature. Terra Nova, 23, 264–269.Google Scholar

  • Mortimer, G.E., Cooper, J.A., Paterson, H.L., Cross, K.C., Hudson, G.R.T., and Uppill, R.K. (1988) Zircon U-Pb dating in the vicinity of the Olympic Dam Cu-U-Au deposit, Roxby Downs, South Australia. Economic Geology and the Bulletin of the Society of Economic Geologists, 83, 694–709.Google Scholar

  • Oreskes, N. (1990) American geological practice: Participation and examination. Part 1: Origin of REE-enriched hematite breccias at Olympic Dam, South Australia. Unpublished Ph.D. thesis, Stamford University, California.Google Scholar

  • Oreskes, N., and Einaudi, M.T. (1990) Origin of rare earth element-enriched hematite breccias at the Olympic Dam Cu-U-Au-Ag deposit, Roxby Downs, South Australia. Economic Geology, 85, 1–28.Google Scholar

  • Oreskes, N., and Einaudi, M.T. (1992) Origin of hydrothermal fluids at Olympic Dam; Preliminary results from fluid inclusions and stable isotopes. Economic Geology, 87, 64–90.Google Scholar

  • Pal, D.C., and Rhede, D. (2013) Geochemistry and chemical dating of uraninite in the Jaduguda Uranium Deposit, Singhbhum Shear Zone, India—Implications for uranium mineralization and geochemical evolution of uraninite. Economic Geology, 108, 1499–1515.Google Scholar

  • Polito, P.A., Kyser, T.K., Marlatt, J., Alexandre, P., Bajwah, Z., and Drever, G. (2004) Significance of alteration assemblages for the origin and evolution of the Proterozoic Nabarlek unconformity-related uranium deposit, Northern Territory, Australia. Economic Geology, 99, 113–139.Google Scholar

  • Putnis, A. (2002) Mineral replacement reactions: From macroscopic observations to microscopic mechanisms. Mineralogical Magazine, 66, 689–708.Google Scholar

  • Ram, R., Charalambous, F.A., McMaster, S., Pownceby, M.I., Tardio, J., and Bhargava, S.K. (2013) Chemical and micro-structural characterisation studies on natural uraninite and associated gangue minerals. Minerals Engineering, 45, 159–169.Google Scholar

  • Reeve, J.S., Cross, K.C., Smith, R.N., and Oreskes, N. (1990) The Olympic Dam copper-uranium-gold-silver deposit, South Australia. In F.E. Hughes, Ed., Geology of Mineral Deposits of Australia and Papua New Guniea, 14, p. 1009–1035. Australian Institute of Mining & Metallurgy Monograph, Melbourne.Google Scholar

  • Roberts, D.E., and Hudson, G.R.T. (1983) The Olympic Dam copper-uranium-gold deposit, Roxby Downs, South Australia. Economic Geology, 78, 799–822.Google Scholar

  • Roudil, D., Bonhoure, J., Pik, R., Cuney, M., Jégou, C., and Gauthier-Lafaye, F. (2008) Diffusion of radiogenic helium in natural uranium oxides. Journal of Nuclear Materials, 378, 70–78.Google Scholar

  • Ruello, P., Petot-Ervas, G., Petot, C., and Desgranges, L. (2005) Electrical conductivity and thermoelectric power of uranium dioxide. Journal of the American Ceramic Society, 88, 604–611.Google Scholar

  • Skirrow, R.G., Bastrakov, E.N., Barovich, K., Fraser, G.L., Creaser, R.A., Fanning, C.M., Raymond, O.L., and Davidson, G.J. (2007) Timing of iron oxide Cu-Au-(U) hydrothermal activity and Nd isotope constraints on metal sources in the Gawler Craton, South Australia. Economic Geology, 102, 1441–1470.Google Scholar

  • Trueman, N.A., Long, J.V.P., Reed, S.J.B., and Chinner, G.A. (1986) The lead-uranium systematics, and rare-earth-element distributions of some Olympic Dam and Stuart Shelf mineralization. Internal Report, Western Mining Corporation, Adelaide.Google Scholar

  • Utsunomiya, S., Palenik, C.S., Valley, J.W., Cavosie, A.J., Wilde, S.A., and Ewing, R.C. (2004) Nanoscale occurrence of Pb in an Archean zircon. Geochimica et Cosmochimica Acta, 68, 4679–4686.Google Scholar

  • Watt, G.R. (1995) High-thorium monazite-(Ce) formed during disequilibrium melting of metapelites under granulite-facies conditions. Mineralogical Magazine, 59, 735–743.Google Scholar

  • Wilson, W.B., Alexander, C.A., and Gerds, A.F. (1961) Stabilization of UO2. Journal of Inorganic and Nuclear Chemistry, 20, 242–251.Google Scholar

  • Wyckoff, R.W.G. (1963) Crystal Structures, 2nd ed. Wiley, New York.Google Scholar

  • Xu, G., Wang, A., Gu, Q., Zhang, J., Zhang, Z., and Huang, Y. (1981) Some characteristics of uranium oxides in China. Bulletin de Mineralogie, 104, 565–574.Google Scholar

  • Zhao, J.-x., and McCulloch, M.T. (1993) Sm-Nd mineral isochron ages of Late Proterozoic dyke swarms in Australia: Evidence for two distinctive events of mafic magmatism and crustal extension. Chemical Geology, 109, 341–354.Google Scholar

About the article

Received: 2015-05-08

Accepted: 2016-01-22

Published Online: 2016-06-03

Published in Print: 2016-06-01


Citation Information: American Mineralogist, Volume 101, Issue 6, Pages 1295–1320, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am-2016-5411.

Export Citation

© 2016 by Walter de Gruyter Berlin/Boston.

Comments (0)

Please log in or register to comment.
Log in