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 language | English (US) |
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Pages (from-to) | 194-202 |
Number of pages | 9 |
Journal | Earth and Planetary Science Letters |
Volume | 357-358 |
DOIs |
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State | Published - 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