TY - JOUR
T1 - Sound velocities and elastic constants of iron-bearing hydrous ringwoodite
AU - Jacobsen, Steven D.
AU - Smyth, Joseph R.
AU - Spetzler, Hartmut
AU - Holl, Christopher M.
AU - Frost, Daniel J.
N1 - Funding Information:
We wish to thank H. Schulze, K. Müller, H. Ohlmeyer, and G. Herrmannsdörfer, S. Linhardt, K. Hain, and K. Klasinski for their technical assistance in construction of the P-to-S conversion buffer rods, high-frequency electronics, and data reduction routines. G. Bromiley assisted with the FTIR measurements. The helpful comments of A. Yoneda and an anonymous reviewer are appreciated. This study was made possible by an Alexander von Humboldt Fellowship to S.D.J. and by the Bayerisches Geoinstitut Visitor Program to J.R.S.
PY - 2004/6/15
Y1 - 2004/6/15
N2 - The sound velocities and single-crystal elastic constants of Fo89 hydrous ringwoodite (γ-Mg1.7 Fe0.22H0.16SiO4) containing ∼10,000 ppm by weight (1 wt.%) H2O have been determined from seven separate pure-mode travel-time measurements using gigahertz ultrasonic interferometry. The experiments feature a new Yttrium-Aluminum- Garnet (YAG) P-to-S conversion shear buffer rod (BR), capable of producing pure ultrasonic shear waves with known polarization in the region of 0.5-2.0 GHz. To our knowledge they are the first such single-crystal ultrasonic measurements on a high-pressure phase recovered from the multi-anvil press. The cubic single-crystal elastic constants of hydrous Fo89 ringwoodite at ambient conditions are (in GPa): c11 = 298 ± 13, c44 = 112 ± 6, and c12 = 115 ± 6. Hydration of Fo∼90 ringwoodite to 1 wt.% H2O reduces the adiabatic bulk (K0S = 176 ± 7 GPa) and shear (G = 103 ± 5 GPa) moduli by about 6 and 13%, roughly equivalent to raising the temperature at room pressure by 600 and 1000 °C, respectively. Assuming a linear trend with hydration, we calculate that P- and S-wave velocities are reduced by about 40 m/s for every 1000 ppm weight (0.1 wt.%) H2O added to Fo∼90 ringwoodite. P- and S-wave velocities of the lower transition zone in PREM are consistent with a hydrated ringwoodite-rich composition.
AB - The sound velocities and single-crystal elastic constants of Fo89 hydrous ringwoodite (γ-Mg1.7 Fe0.22H0.16SiO4) containing ∼10,000 ppm by weight (1 wt.%) H2O have been determined from seven separate pure-mode travel-time measurements using gigahertz ultrasonic interferometry. The experiments feature a new Yttrium-Aluminum- Garnet (YAG) P-to-S conversion shear buffer rod (BR), capable of producing pure ultrasonic shear waves with known polarization in the region of 0.5-2.0 GHz. To our knowledge they are the first such single-crystal ultrasonic measurements on a high-pressure phase recovered from the multi-anvil press. The cubic single-crystal elastic constants of hydrous Fo89 ringwoodite at ambient conditions are (in GPa): c11 = 298 ± 13, c44 = 112 ± 6, and c12 = 115 ± 6. Hydration of Fo∼90 ringwoodite to 1 wt.% H2O reduces the adiabatic bulk (K0S = 176 ± 7 GPa) and shear (G = 103 ± 5 GPa) moduli by about 6 and 13%, roughly equivalent to raising the temperature at room pressure by 600 and 1000 °C, respectively. Assuming a linear trend with hydration, we calculate that P- and S-wave velocities are reduced by about 40 m/s for every 1000 ppm weight (0.1 wt.%) H2O added to Fo∼90 ringwoodite. P- and S-wave velocities of the lower transition zone in PREM are consistent with a hydrated ringwoodite-rich composition.
KW - Elastic properties
KW - Gigahertz ultrasonic interferometry
KW - Hydrogen in the transition zone
KW - Hydrous ringwoodite
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U2 - 10.1016/j.pepi.2003.07.019
DO - 10.1016/j.pepi.2003.07.019
M3 - Article
AN - SCOPUS:2442593617
SN - 0031-9201
VL - 143
SP - 47
EP - 56
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
IS - 1-2
ER -