Stability, composition, and crystal structure of Fe-bearing Phase E in the transition zone

Li Zhang*, Joseph R. Smyth, Takaaki Kawazoe, Steven D. Jacobsen, Jingjing Niu, Xuejing He, Shan Qin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Fe-bearing phase E coexisting with ringwoodite and wadsleyite has been synthesized at near-geotherm temperatures in hydrous KLB-1 peridotite compositions held at 18 and 19 GPa, and 1400 °C for 27 h. The long heating duration time of syntheses implies that phase E can be a stable component of the mantle under hydrous conditions. Single-crystal X-ray diffraction analyses show that the M1 octahedral site is 72.1-75.2 at% occupied, whereas the M2 and tetrahedral Si sites are 2.4-2.9 at% and 18.9-19.8 at% occupied, respectively. The M1 site occupancies show a positive correlation with Fe/Mg molar ratios, indicating that Fe mainly occupies the M1 site in the phase E structure. High-pressure Raman spectroscopy shows that the framework Raman frequencies of Fe-bearing phase E increase continuously with increasing pressures up to 19 GPa at room temperature, and there is no indication for a major change in the crystal structure. If transition-zone regions adjacent to subducting slabs are hydrated by fluids generated at the top of the lower mantle, Fe-bearing phase E is expected to occur at wadsleyite-ringwoodite phase transition boundary (about 520 km) as an important phase for incorporating water.

Original languageEnglish (US)
Pages (from-to)1620-1624
Number of pages5
JournalAmerican Mineralogist
Volume104
Issue number11
DOIs
StatePublished - Nov 26 2019

Keywords

  • Phase E
  • X-ray diffraction
  • high-pressure Raman spectroscopy
  • transition zone

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Fingerprint

Dive into the research topics of 'Stability, composition, and crystal structure of Fe-bearing Phase E in the transition zone'. Together they form a unique fingerprint.

Cite this