Sn-isotope fractionation as a record of hydrothermal redox reactions

Junming Yao, Ryan Mathur, Wayne Powell, Bernd Lehmann, Fernando Tornos, Marc Wilson, Joaquin Ruiz

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

A redox reaction in which Sn2+ oxidizes to Sn4+ is thought to occur during the precipitation of cassiterite (SnO2) and stannite (Cu2FeSnS4) from high-temperature hydrothermal solutions. In four stanniferous regions with differing mineralization environments (South Dakota, U.S.A.; Cornwall, England; Erzgebirge, Germany/Czech Republic; Andean tin belt, Bolivia), the tin isotope composition in stannite (mean value δ124Sn = -1.47 ± 0.54‰, n = 21) is consistently more fractionated toward negative values than that of paragenetically earlier cassiterite (mean value δ124Sn = 0.48 ± 0.62‰, n = 50). Given the oxidation-dependent mechanism for cassiterite precipitation, this isotopic shift is most likely attributable to the oxidation of Sn in solution; precipitation of heavy-Sn-enriched cassiterite results in residual dissolved Sn with lighter isotopic composition, which is expressed in the negative δ124Sn values of later-formed stannite. Equally important is that the mean values for the cassiterite from the various deposits are slightly different and may indicate that the initial Sn isotope composition in early-formed cassiterite relates to variations in the source or magmatic processes. Therefore, the Sn isotopes may provide information on both redox reactions and petrologic sources and processes.

Original languageEnglish (US)
Pages (from-to)1591-1598
Number of pages8
JournalAmerican Mineralogist
Volume103
Issue number10
DOIs
Publication statusPublished - Oct 25 2018

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Keywords

  • cassiterite
  • metal isotope fractionation
  • redox
  • stannite
  • Tin isotopes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Cite this

Yao, J., Mathur, R., Powell, W., Lehmann, B., Tornos, F., Wilson, M., & Ruiz, J. (2018). Sn-isotope fractionation as a record of hydrothermal redox reactions. American Mineralogist, 103(10), 1591-1598. https://doi.org/10.2138/am-2018-6524