Synthesis and equation of state of perovskites in the (Mg, Fe)3Al2Si3O12 system to 177GPa

Susannah M. Dorfman, Sean R. Shieh, Yue Meng, Vitali B. Prakapenka, Thomas S. Duffy

Research output: Contribution to journalComment/debate

14 Scopus citations

Abstract

Natural and synthetic pyrope-almandine compositions from 38 to 100 mol% almandine (Alm38-Alm100) werestudied by synchrotron X-ray diffraction in the laser-heate ddiamond anvil cell to 177 GPa. Single-phase orthorhombic GdFeO3-type perovskites were synthesized across the entire examined compositional range at deep lower mantle pressures, with higher Fe-contents requiring higher synthesis pressures. The formation of perovskite with Alm100 (Fe3Al2Si3O12) composition at 80 GPa marks the first observation of asilicateperovskiteinaFe end-member.Fe- enrichment broadens and lowers the pressurerange of the post-perovskite transition for intermediate compositions suchas Alm54, but the more Fe-richAlm100-composition perovskite remains stable to pressures as highas 149 GPa. Volume compression data for the Alm54 and Alm100 compositions were fit to the Birch-Murnaghan equation of state. The compressibility of perovskites synthesized from compositions long the pyrope-almandine join is not strongly sensitive to Fecontent. The compression curves were smooth over the entire measured range, and no evidence for a volume anomaly associated with a spin transition was observed.

Original languageEnglish (US)
Pages (from-to)194-202
Number of pages9
JournalEarth and Planetary Science Letters
Volume357-358
DOIs
StatePublished - Dec 1 2012

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Keywords

  • D″; region
  • Lower mantle
  • Perovskite
  • Post-perovskite

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