The transition of orthoferrosilite to high-pressure C2/c clinoferrosilite at ambient temperature

Demelza Hugh-Jones, Thomas Sharp, Ross Angel, Alan Woodland

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

High-pressure single-crystal X-ray diffraction experiments on FeSiO3 orthoferrosilite have revealed that at pressures above ∼4.2GPa, the orthopyroxene transforms to a new phase. Examination by transmission electron microscopy of transformed material recovered from the diamond-anvil cell shows that the final product is predominantly low-clinoferrosilite (space group P21lc) with a few small islands of metastable C2lc clinoferrosilite. The presence of the C2/c clinoferrosilite, and the fact that this phase transforms readily to low-clinoferrosilite upon decompression below ∼1.5 GPa in hydrostatic conditions, confirms that the high-pressure clinoferrosilite was formed by the breakdown of orthoferrosilite at ∼4.2 GPa. The sequence of transformations is therefore: orthoferrosilite (Pbca) → (P increase above 4.2 GPa) → high-P clinoferrosilite (C2/c) → (P release below 1.5 GPa) → low-clinoferrosilite (P21lc) The transformation of orthoferrosilite to the high-pressure C2lc clinoferrosilite is highly time-dependent and first-order in character, accompanied by a ∼2.6% volume discontinuity. The morphology and microstructure of the recovered transformation products is indicative of a reconstructive transformation mechanism similar to that proposed previously for other orthopyroxene to clinopyroxene transformations.

Original languageEnglish (US)
Pages (from-to)1337-1345
Number of pages9
JournalEuropean Journal of Mineralogy
Volume8
Issue number6
StatePublished - Nov 1996
Externally publishedYes

Fingerprint

orthopyroxene
temperature
transform
Temperature
Diamond
diamond anvil cell
decompression
hydrostatics
clinopyroxene
Single crystals
transmission electron microscopy
Transmission electron microscopy
microstructure
discontinuity
X ray diffraction
Microstructure
X-ray diffraction
crystal
Experiments
experiment

Keywords

  • Ferrosilite
  • FeSiO
  • High pressure
  • Phase transition

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

The transition of orthoferrosilite to high-pressure C2/c clinoferrosilite at ambient temperature. / Hugh-Jones, Demelza; Sharp, Thomas; Angel, Ross; Woodland, Alan.

In: European Journal of Mineralogy, Vol. 8, No. 6, 11.1996, p. 1337-1345.

Research output: Contribution to journalArticle

Hugh-Jones, Demelza ; Sharp, Thomas ; Angel, Ross ; Woodland, Alan. / The transition of orthoferrosilite to high-pressure C2/c clinoferrosilite at ambient temperature. In: European Journal of Mineralogy. 1996 ; Vol. 8, No. 6. pp. 1337-1345.
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