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Mungall JE, Hanley JJ, Arndt NT, et al. Evidence from meimechites and other low-degree mantle melts for redox controls on mantle-crust fractionation of platinum-group elements. Proc Natl Acad Sci U S A. 2006;103(34):12695-700doi: 10.1073/pnas.0600878103.
Mungall, J. E., Hanley, J. J., Arndt, N. T., & Debecdelievre, A. (2006). Evidence from meimechites and other low-degree mantle melts for redox controls on mantle-crust fractionation of platinum-group elements. Proceedings of the National Academy of Sciences of the United States of America, 103(34), 12695-700. https://doi.org/10.1073/pnas.0600878103
Mungall, James E, et al. "Evidence from meimechites and other low-degree mantle melts for redox controls on mantle-crust fractionation of platinum-group elements." Proceedings of the National Academy of Sciences of the United States of America vol. 103,34 (2006): 12695-700. doi: https://doi.org/10.1073/pnas.0600878103
Mungall JE, Hanley JJ, Arndt NT, Debecdelievre A. Evidence from meimechites and other low-degree mantle melts for redox controls on mantle-crust fractionation of platinum-group elements. Proc Natl Acad Sci U S A. 2006 Aug 22;103(34):12695-700. doi: 10.1073/pnas.0600878103. Epub 2006 Aug 14. PMID: 16908861; PMCID: PMC1568912.
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Proc Natl Acad Sci U S A. 2006 Aug 22;103(34):12695-700. doi: 10.1073/pnas.0600878103. Epub 2006 Aug 14.

Evidence from meimechites and other low-degree mantle melts for redox controls on mantle-crust fractionation of platinum-group elements.

Proceedings of the National Academy of Sciences of the United States of America

James E Mungall, Jacob J Hanley, Nicholas T Arndt, Anne Debecdelievre

Affiliations

  1. Department of Geology, University of Toronto, 22 Russell Street, Toronto, ON, Canada M5S 3B1. [email protected]

PMID: 16908861 PMCID: PMC1568912 DOI: 10.1073/pnas.0600878103

Abstract

Understanding of the geochemistry of the chalcophile elements [i.e., Os, Ir, Ru, Pt, Pd (platinum-group elements), and Au, Cu, Ni] has been informed for at least 20 years by the common assumption that when crust-forming partial melts are extracted from the upper mantle, sulfide liquid in the restite sequesters chalcophile elements until the extent of partial melting exceeds approximately 25% and all of the sulfide has been dissolved in silicate melt [Hamlyn, P. R. & Keays, R. R. (1985) Geochim. Cosmochim. Acta 49, 1797-1811]. Here we document very high, unfractionated, chalcophile element concentrations in small-degree partial melts from the mantle that cannot be reconciled with the canonical residual sulfide assumption. We show that the observed high, unfractionated platinum-group element concentrations in small-degree partial melts can be attained if the melting takes place at moderately high oxygen fugacity, which will reduce the amount of sulfide due to the formation of sulfate and will also destabilize residual monosulfide solid solution by driving sulfide melts into the spinel-liquid divariant field. Magmas formed at high oxygen fugacity by small degrees of mantle melting can be important agents for the transfer of chalcophile elements from the upper mantle to the crust and may be progenitors of significant ore deposits of Pt, Pd, and Au.

References

  1. Nature. 2004 Oct 21;431(7011):975-8 - PubMed
  2. Science. 2004 Sep 24;305(5692):1951-3 - PubMed

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