The redox state, FeO content, and origin of sulfur-rich magmas on Mercury

Mikhail Zolotov, Ann L. Sprague, Steven A. Hauck, Larry R. Nittler, Sean C. Solomon, Shoshana Z. Weider

Research output: Contribution to journalArticlepeer-review

73 Scopus citations

Abstract

MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) orbital observations of Mercury have revealed elevated S abundances, Ca-S and Mg-S correlations, and a low upper limit for ferrous iron in surface silicates. These data indicate the presence of Ca and/or Mg sulfides in volcanic rocks and a low oxygen fugacity (fO2) in their parental magmas. We have evaluated coupled fO2 and fS2 values and FeO contents in Mercury's magmas from silicate-sulfide equilibria and empirical models for silicate melts and metallurgical slags. The evaluated fO2 at 1700-1800 K is 4.5 to 7.3 log10 units below the iron-wüstite buffer. These values correspond to 0.028-0.79 wt % FeO, implying that Fe must be also present in sulfides and metal and are also consistent with the composition of the partial melt of an enstatite chondrite. This derived upper limit for FeO is substantially lower than the limits obtained from reflectance measurements of Mercury's surface materials. The low fO2 and FeO values provide new constraints for igneous processes on Mercury as well as the formation, evolution, and internal structure of the innermost planet.

Original languageEnglish (US)
Pages (from-to)138-146
Number of pages9
JournalJournal of Geophysical Research E: Planets
Volume118
Issue number1
DOIs
StatePublished - 2013

Keywords

  • Mercury
  • oxygen fugacity
  • slags
  • sulfides
  • sulfur fugacity
  • volcanism

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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