Complexation of gold in S3 --rich hydrothermal fluids: Evidence from ab-initio molecular dynamics simulations

Yuan Mei*, David M. Sherman, Weihua Liu, Joël Brugger

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

31 Citations (Scopus)

Abstract

Recent Raman spectroscopic studies suggest that S3 - is an important sulfur species in magmatic hydrothermal and metamorphic fluids at P>0.5GPa and T>250°C, and may be an important ligand for metal transport (Pokrovski and Dubrovinsky, 2011). Based on static Density Functional Theory calculations, Tossell (2012) confirmed the stability of the S3 - ion, and suggested some possible Cu-S3 complexes in the ideal gas phase and in aqueous solution. We investigated the complexation of Au and S3 - in aqueous fluids by ab-initio molecular dynamics (MD) simulations. We performed ab-initio MD simulations in aqueous solution at 300°C, 0.5 and 2GPa to investigate the competition among the S3 -, HS-, H2S(aq), OH- and H2O ligands for Au+, aiming at evaluating the significance of the 'exotic' S3 - ligand for Au metallogenesis. The results indicate that, in contrast to results of static calculations that show a symmetric Au-S3 complex with bidentate structure, Au+ forms linear complexes with S3 -. The stoichiometry of these complexes depends on pH and fluid composition (e.g., Au(H2O)S3(aq); Au(HS)S3 -; Au(OH)S3 -; Au(S3)2 -). The S3 - and bisulfide (HS-) ions are ligands of similar strength for Au+; this confirms Pokrovski and Dubrovinsky's (2011) assumption that such 'exotic' ligands may play a major role in promoting Au mobility in magmatic and metamorphic environments.

Original languageEnglish
Pages (from-to)34-42
Number of pages9
JournalChemical Geology
Volume347
DOIs
Publication statusPublished - 6 Jun 2013

Keywords

  • Computational chemistry
  • Gold transport
  • Hydrothermal ore deposits
  • Molecular dynamics
  • Quantum chemistry
  • S ion

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    TRANSPORT OF LITHOPHILE ELEMENTS IN MAGMATIC-HYDROTHERMAL FLUIDS

    Sherman, D. M.

    1/09/111/09/14

    Project: Research

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