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American Mineralogist

Journal of Earth and Planetary Materials

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


IMPACT FACTOR 2017: 2.645

CiteScore 2017: 2.31

SCImago Journal Rank (SJR) 2017: 1.440
Source Normalized Impact per Paper (SNIP) 2017: 1.059

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1945-3027
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Volume 100, Issue 8-9

Issues

Uranium scavenging during mineral replacement reactions

Kan Li / Allan Pring
  • Division of Mineralogy, South Australian Museum, North Terrace, 5000, Adelaide, South Australia, Australia
  • School of Chemical and Physical Sciences, Flinders University, 5001, South Australia, Australia
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/ Barbara Etschmann
  • School of Chemical Engineering, The University of Adelaide, 5000, South Australia, Australia
  • Division of Mineralogy, South Australian Museum, North Terrace, 5000, Adelaide, South Australia, Australia
  • School of Earth, Atmosphere, and Environment, Monash University, 3800, Clayton, Victoria, Australia
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/ Edeltraud Macmillan
  • School of Earth and Environmental Sciences, The University of Adelaide, 5000, South Australia, Australia
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/ Yung Ngothai / Brian O’Neill / Anthony Hooker
  • School of Chemical Engineering, The University of Adelaide, 5000, South Australia, Australia
  • Radiation Health, Radiation Protection Branch, Environment Protection Authority, Victoria SQ, 5000, Adelaide, South Australia, Australia
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/ Fred Mosselmans
  • Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
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/ Joël Brugger
  • Corresponding author
  • Division of Mineralogy, South Australian Museum, North Terrace, 5000, Adelaide, South Australia, Australia
  • School of Earth, Atmosphere, and Environment, Monash University, 3800, Clayton, Victoria, Australia
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Published Online: 2015-08-12 | DOI: https://doi.org/10.2138/am-2015-5125

Abstract

Interface coupled dissolution-reprecipitation reactions (ICDR) are a common feature of fluid-rock interaction during crustal fluid flow. We tested the hypothesis that ICDR reactions can play a key role in scavenging minor elements by exploring the fate of U during the experimental sulfidation of hematite to chalcopyrite under hydrothermal conditions (220-300 °C). The experiments where U was added, either as solid UO2+x(s) or as a soluble uranyl complex, differed from the U-free experiments in that pyrite precipitated initially, before the onset of chalcopyrite precipitation. In addition, in UO2+x(s)- bearing experiments, enhanced hematite dissolution led to increased porosity and precipitation of pyrite+magnetite within the hematite core, whereas in uranyl nitrate-bearing experiments, abundant pyrite formed initially, before being replaced by chalcopyrite. Uranium scavenging was mainly associated with the early reaction stage (pyrite precipitation), resulting in a thin U-rich line marking the original hematite grain surface. This “line” consists of nanocrystals of UO2+x(s), based on chemical mapping and XANES spectroscopy. This study shows that the presence of minor components can affect the pathway of ICDR reactions. Reactions between U- and Cu-bearing fluids and hematite can explain the Cu-U association prominent in some iron oxide-copper-gold (IOCG) deposits.

Keywords: Uranium; scavenging; IOCG deposits; experiment; sulfidation reaction; interface coupled dissolution-reprecipitation reactions

About the article

Received: 2014-07-13

Accepted: 2015-02-03

Published Online: 2015-08-12

Published in Print: 2015-08-01


Citation Information: American Mineralogist, Volume 100, Issue 8-9, Pages 1728–1735, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am-2015-5125.

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© 2015 by Walter de Gruyter Berlin/Boston.

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