In situ measurements of sound velocities and densities across the orthopyroxene ρarr; high-pressure clinopyroxene transition in MgSiO3 at high pressure

Jennifer Kung, Baosheng Li, Takeyuki Uchida, Yanbin Wang, Daniel Neuville, Robert C. Liebermann

Research output: Contribution to journalArticlepeer-review

90 Citations (Scopus)

Abstract

Using acoustic measurement interfaced with a large volume multi-anvil apparatus in conjunction with in situ X-radiation techniques, we are able to measure the density and elastic wave velocities (VP and VS) for both ortho- and high-pressure clino-MgSiO3 polymorphs in the same experimental run. The elastic bulk and shear moduli of the unquenchable high-pressure clinoenstatite phase were measured within its stability field for the first time. The measured density contrast associated with the phase transition OEN → HP-CEN is 2.6-2.9% in the pressure of 7-9 GPa, and the corresponding velocity jumps are 3-4% for P waves and 5-6% for S waves. The elastic moduli of the HP-CEN phase are KS=156.7(8) GPa, G = 98.5(4) GPa and their pressure derivatives are KS′=5.5(3) and G′ = 1.5(1) at a pressure of 6.5 GPa, room temperature. In addition, we observed anomalous elastic behavior in orthoenstatite at pressure above 9 GPa at room temperature. Both elastic wave velocities exhibited softening between 9 and 13-14 GPa, which we suggest is associated with a transition to a metastable phase intermediate between OEN and HP-CEN.

Original languageEnglish
Pages (from-to)27-44
Number of pages18
JournalPhysics of the Earth and Planetary Interiors
Volume147
Issue number1
DOIs
Publication statusPublished - 2004 Oct 15

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science

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