Contributions to Mineralogy and Petrology

, Volume 150, Issue 5, pp 473–485

Hydrogen incorporation in orthopyroxene: interaction of different trivalent cations

  • Roland Stalder
  • Stephan Klemme
  • Thomas Ludwig
  • Henrik Skogby
Original Paper

DOI: 10.1007/s00410-005-0037-4

Cite this article as:
Stalder, R., Klemme, S., Ludwig, T. et al. Contrib Mineral Petrol (2005) 150: 473. doi:10.1007/s00410-005-0037-4

Abstract

The incorporation of hydrogen into ferrosilite, Fe-bearing enstatite and orthopyroxene containing different trivalent cations (Cr3+ and Al3+, Cr3+ and Fe3+) was investigated experimentally at 25 kbar. Hydrogen concentration was determined by FTIR-spectroscopy on oriented crystal sections and by secondary ion mass spectroscopy, whereas Mößbauer spectroscopy and optical spectroscopy were used to characterise the valence state of Fe in orthopyroxene. Results suggest that hydrogen incorporation in ferrosilite is achieved by a similar mechanism as in pure enstatite. In Cr-bearing samples, however, hydrogen incorporation is reduced by the presence of other trivalent cations by an increased tendency to form Tschermaks substitutions, e.g. SiT4+ + MgM12+ ⇔ AlT3+ + CrM13+. Thus, hydrogen solubility in natural orthopyroxenes from the Earth’s mantle, containing significant amounts of Cr3+, Al3+, and Fe3+, may be much more limited than expected from their trivalent cation content, as a large fraction of the trivalent cations does not participate in H-incorporating reactions as 2 MgM12+ ⇔ MM13+ + VM1 + Hi+.

Keywords

Orthopyroxene Hydrogen incorporation Trivalent cation High pressure Spectroscopy 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Roland Stalder
    • 1
  • Stephan Klemme
    • 2
  • Thomas Ludwig
    • 2
  • Henrik Skogby
    • 3
  1. 1.Abteilung Angewandte und Experimentelle MineralogieGeowissenschaftliches Zentrum der Universität GöttingenGöttingenGermany
  2. 2.Mineralogisches Institut der Universität HeidelbergHeidelbergGermany
  3. 3.Naturhistoriska riksmuseetSektionen för mineralogiStockholmSweden

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