Sound velocities and elastic properties of γ-Mg_2SiO_4 to 873 K by Brillouin spectroscopy
Abstract
The sound velocities and single-crystal elastic moduli of spinel-structured γ-Mg_2SiO_4 were measured to 873 K by Brillouin spectroscopy using a new high-temperature cell designed for single-crystal measurements. These are the first reported acoustic measurements of γ-Mg_2SiO_4 elasticity at high temperatures. A linear decrease of elastic moduli and sound velocities with temperature adequately describes the data. The adiabatic bulk modulus, K_S, shear modulus, μ, and respective temperature derivatives for γ-Mg_2SiO_4 are: K_S = 185(3) GPa, μ = 120.4(2.0) GPa, (∂K_S/∂T)_P = −0.024(3) GPa/K and (∂μ/∂T)_P = −0.015(2) GPa/K. Extrapolation of our data to transition zone pressures and temperatures indicates that the shear and compressional impedance contrasts associated with β- →γ-(Mg,Fe)_2SiO_4 transition are sufficient to produce an observable discontinuity at 520 km depth, even with a moderate (30–50%) amount of olivine.
Additional Information
© 2000 Mineralogical Society of America. Manuscript Received Apri 7, 1999. Manuscript Accepted September 29, 1999. Paper handled by Robert C. Liebermann. We thank Donald J. Weidner and the Center for High Pressure Research (CHiPR) for providing the samples used in this study. We also thank James Palko for help in constructing the high-temperature cell. This research was supported by NSF. Jennifer M. Jackson was supported in part by the Research Experiences for Undergraduates program of the NSF.Additional details
- Eprint ID
- 43990
- Resolver ID
- CaltechAUTHORS:20140225-143137368
- NSF
- NSF Research Experiences for Undergraduates Program
- Created
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2014-02-25Created from EPrint's datestamp field
- Updated
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2020-01-24Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory, Division of Geological and Planetary Sciences