Abstract
Single-crystal elastic moduli of synthetic iron-bearing majoritic garnet were measured using Brillouin spectroscopy up to a pressure of 26 GPa. We found that the iron-bearing majoritic garnet (Mg0.79Fe0.08Al0.30Si0.84O3) remains elastically isotropic throughout the pressure range of this study. The shear and adiabatic bulk moduli and their pressure derivatives at zero pressure were determined to be μ0 = 88.7(7) GPa, KS0 = 166(2) GPa, (∂μ / ∂P)0 = 1.28(8), (∂K / ∂P)0 = 4.2(2). These values are almost indistinguishable, within the experimental uncertainties, from those obtained in previous studies of pure MgSiO3 majorite and other solid solutions of the majorite-pyrope join. Our direct acoustic velocity measurements of iron-bearing majorite indicate that the incorporation of iron into majoritic garnet does not drastically affect its elastic moduli and their pressure derivatives. The measured pressure derivatives of iron-bearing majorite are about 3.6 times lower than required to account for the high seismic velocity gradients observed in the mantle transition zone.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 339-345 |
| Number of pages | 7 |
| Journal | Earth and Planetary Science Letters |
| Volume | 274 |
| Issue number | 3-4 |
| DOIs | |
| State | Published - Oct 15 2008 |
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Keywords
- elasticity
- high pressure
- majorite
- mantle transition zone
- seismic velocity structure
- sound velocity
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
Cite this
Single-crystal elasticity of iron-bearing majorite to 26 GPa : Implications for seismic velocity structure of the mantle transition zone. / Murakami, Motohiko; Sinogeikin, Stanislav V.; Litasov, Konstantin; Ohtani, Eiji; Bass, Jay D.
In: Earth and Planetary Science Letters, Vol. 274, No. 3-4, 15.10.2008, p. 339-345.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Single-crystal elasticity of iron-bearing majorite to 26 GPa
T2 - Implications for seismic velocity structure of the mantle transition zone
AU - Murakami, Motohiko
AU - Sinogeikin, Stanislav V.
AU - Litasov, Konstantin
AU - Ohtani, Eiji
AU - Bass, Jay D
PY - 2008/10/15
Y1 - 2008/10/15
N2 - Single-crystal elastic moduli of synthetic iron-bearing majoritic garnet were measured using Brillouin spectroscopy up to a pressure of 26 GPa. We found that the iron-bearing majoritic garnet (Mg0.79Fe0.08Al0.30Si0.84O3) remains elastically isotropic throughout the pressure range of this study. The shear and adiabatic bulk moduli and their pressure derivatives at zero pressure were determined to be μ0 = 88.7(7) GPa, KS0 = 166(2) GPa, (∂μ / ∂P)0 = 1.28(8), (∂K / ∂P)0 = 4.2(2). These values are almost indistinguishable, within the experimental uncertainties, from those obtained in previous studies of pure MgSiO3 majorite and other solid solutions of the majorite-pyrope join. Our direct acoustic velocity measurements of iron-bearing majorite indicate that the incorporation of iron into majoritic garnet does not drastically affect its elastic moduli and their pressure derivatives. The measured pressure derivatives of iron-bearing majorite are about 3.6 times lower than required to account for the high seismic velocity gradients observed in the mantle transition zone.
AB - Single-crystal elastic moduli of synthetic iron-bearing majoritic garnet were measured using Brillouin spectroscopy up to a pressure of 26 GPa. We found that the iron-bearing majoritic garnet (Mg0.79Fe0.08Al0.30Si0.84O3) remains elastically isotropic throughout the pressure range of this study. The shear and adiabatic bulk moduli and their pressure derivatives at zero pressure were determined to be μ0 = 88.7(7) GPa, KS0 = 166(2) GPa, (∂μ / ∂P)0 = 1.28(8), (∂K / ∂P)0 = 4.2(2). These values are almost indistinguishable, within the experimental uncertainties, from those obtained in previous studies of pure MgSiO3 majorite and other solid solutions of the majorite-pyrope join. Our direct acoustic velocity measurements of iron-bearing majorite indicate that the incorporation of iron into majoritic garnet does not drastically affect its elastic moduli and their pressure derivatives. The measured pressure derivatives of iron-bearing majorite are about 3.6 times lower than required to account for the high seismic velocity gradients observed in the mantle transition zone.
KW - elasticity
KW - high pressure
KW - majorite
KW - mantle transition zone
KW - seismic velocity structure
KW - sound velocity
UR - http://www.scopus.com/inward/record.url?scp=52749083571&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=52749083571&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2008.07.045
DO - 10.1016/j.epsl.2008.07.045
M3 - Article
AN - SCOPUS:52749083571
VL - 274
SP - 339
EP - 345
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
IS - 3-4
ER -