Abstract
Sound velocities and elastic moduli have been measured on Fe-bearing orthoenstatite (OEN) single crystals up to 12 GPa by Brillouin spectroscopy. The ambient adiabatic bulk modulus (Ks0) and shear modulus (G0) are determined to be 113(1) GPa and 75.9(7) GPa, respectively. A fourth-order finite strain fit to the data yields pressure derivatives of Ks0′ = 8.8(1), Ks0″ = −0.68(6), G0′ = 2.9(1), and G0″ = −0.40(2). These values are significantly higher than those for other major mantle minerals up to 10.5 GPa but lower than some previous measurements on OEN. A pronounced increase of shear anisotropy was observed at a pressure of 12.06(9) GPa, coinciding with a phase transition from orthoenstatite to a recently discovered high-pressure phase with space group P21/c. A high-pressure phase transition in OEN is unlikely to be the cause of the X discontinuity in the 250–325 km depth range. Rather, a change in seismic anisotropy would be expected to accompany the orthoenstatite-to-P21/c phase transition in the upper mantle at greater depths.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 8473-8481 |
| Number of pages | 9 |
| Journal | Geophysical Research Letters |
| Volume | 43 |
| Issue number | 16 |
| DOIs | |
| State | Published - Aug 28 2016 |
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Keywords
- OEN-HPCEN2 transition
- X discontinuity
- high pressure
- orthoenstatite
- single-crystal elasticity
ASJC Scopus subject areas
- Geophysics
- Earth and Planetary Sciences(all)
Cite this
Single-crystal elasticity of natural Fe-bearing orthoenstatite across a high-pressure phase transition. / Zhang, Jin S.; Bass, Jay D.
In: Geophysical Research Letters, Vol. 43, No. 16, 28.08.2016, p. 8473-8481.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Single-crystal elasticity of natural Fe-bearing orthoenstatite across a high-pressure phase transition
AU - Zhang, Jin S.
AU - Bass, Jay D
PY - 2016/8/28
Y1 - 2016/8/28
N2 - Sound velocities and elastic moduli have been measured on Fe-bearing orthoenstatite (OEN) single crystals up to 12 GPa by Brillouin spectroscopy. The ambient adiabatic bulk modulus (Ks0) and shear modulus (G0) are determined to be 113(1) GPa and 75.9(7) GPa, respectively. A fourth-order finite strain fit to the data yields pressure derivatives of Ks0′ = 8.8(1), Ks0″ = −0.68(6), G0′ = 2.9(1), and G0″ = −0.40(2). These values are significantly higher than those for other major mantle minerals up to 10.5 GPa but lower than some previous measurements on OEN. A pronounced increase of shear anisotropy was observed at a pressure of 12.06(9) GPa, coinciding with a phase transition from orthoenstatite to a recently discovered high-pressure phase with space group P21/c. A high-pressure phase transition in OEN is unlikely to be the cause of the X discontinuity in the 250–325 km depth range. Rather, a change in seismic anisotropy would be expected to accompany the orthoenstatite-to-P21/c phase transition in the upper mantle at greater depths.
AB - Sound velocities and elastic moduli have been measured on Fe-bearing orthoenstatite (OEN) single crystals up to 12 GPa by Brillouin spectroscopy. The ambient adiabatic bulk modulus (Ks0) and shear modulus (G0) are determined to be 113(1) GPa and 75.9(7) GPa, respectively. A fourth-order finite strain fit to the data yields pressure derivatives of Ks0′ = 8.8(1), Ks0″ = −0.68(6), G0′ = 2.9(1), and G0″ = −0.40(2). These values are significantly higher than those for other major mantle minerals up to 10.5 GPa but lower than some previous measurements on OEN. A pronounced increase of shear anisotropy was observed at a pressure of 12.06(9) GPa, coinciding with a phase transition from orthoenstatite to a recently discovered high-pressure phase with space group P21/c. A high-pressure phase transition in OEN is unlikely to be the cause of the X discontinuity in the 250–325 km depth range. Rather, a change in seismic anisotropy would be expected to accompany the orthoenstatite-to-P21/c phase transition in the upper mantle at greater depths.
KW - OEN-HPCEN2 transition
KW - X discontinuity
KW - high pressure
KW - orthoenstatite
KW - single-crystal elasticity
UR - http://www.scopus.com/inward/record.url?scp=84983672041&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84983672041&partnerID=8YFLogxK
U2 - 10.1002/2016GL069963
DO - 10.1002/2016GL069963
M3 - Article
AN - SCOPUS:84983672041
VL - 43
SP - 8473
EP - 8481
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 16
ER -