American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 450941 bytes)    Cited by

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, B09203, doi:10.1029/2005JB004052, 2006

Single-crystal elasticity and sound velocities of (Mg0.94Fe0.06)O ferropericlase to 20 GPa

Jennifer M. Jackson

Department of Geology, University of Illinois, Urbana, Illinois, USA


Stanislav V. Sinogeikin

Department of Geology, University of Illinois, Urbana, Illinois, USA


Steven D. Jacobsen

Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C., USA


Hans J. Reichmann

GeoForschungsZentrum, Potsdam, Germany


Stephen J. Mackwell

Lunar and Planetary Institute, Houston, Texas, USA


Jay D. Bass

Department of Geology, University of Illinois, Urbana, Illinois, USA


Abstract

The single-crystal elastic properties of high-spin (Mg0.94Fe0.06)O ferropericlase were measured by Brillouin spectroscopy on a sample compressed to 20 GPa with diamond anvil cells using methanol-ethanol-water as a pressure-transmitting medium. At room pressure, the adiabatic bulk (K 0S) and shear (μ0S) moduli are K 0S = 163 ± 3 GPa and μ0S = 121 ± 2 GPa, in excellent agreement with ultrasonic results from the same bulk sample (Jacobsen et al., 2002). A fit to all our high-pressure Brillouin data using a third-order finite-strain equation of state yields the following pressure derivatives of the adiabatic bulk and shear moduli: K′0S = 3.9 ± 0.2 and μ′0S = 2.1 ± 0.1. Within the uncertainties, we find that K 0S and K′0S of (Mg0.94Fe0.06)O are unchanged from MgO. However, μ0S and μ′0S of (Mg0.94Fe0.06)O are reduced by 8% and 11%, respectively. The aggregate compressional (V P) and shear (V S) wave velocities are reduced by 4% and 6%, respectively, as compared to MgO. The pressure dependence of the single-crystal elastic moduli and aggregate sound velocities is linear within the investigated pressure range. The elastic anisotropy of (Mg0.94Fe0.06)O is about 10% greater than that of MgO at ambient conditions. At the highest pressure obtained here, the elastic anisotropy of (Mg0.94Fe0.06)O is close to zero. On the basis of our measurements and earlier ultrasonic measurements, we find that the pressure derivatives of shear moduli obtained at room pressure for low iron concentrations (<20 mol% FeO) of high-spin ferropericlase are inconsistent with those inferred from the lower mantle PREM model.

Received 15 September 2005; accepted 6 March 2006; published 7 September 2006.

Keywords: ferropericlase; elasticity; high-pressure.

Index Terms: 3909 Mineral Physics: Elasticity and anelasticity; 3919 Mineral Physics: Equations of state; 3924 Mineral Physics: High-pressure behavior; 3934 Mineral Physics: Optical, infrared, and Raman spectroscopy.

Read Full Article (file size: 450941 bytes)    Cited by

Citation: Jackson, J. M., S. V. Sinogeikin, S. D. Jacobsen, H. J. Reichmann, S. J. Mackwell, and J. D. Bass (2006), Single-crystal elasticity and sound velocities of (Mg0.94Fe0.06)O ferropericlase to 20 GPa, J. Geophys. Res., 111, B09203, doi:10.1029/2005JB004052.