Elasticity of a majorite-pyrope solid solution
- Univ. of Illinois, Urbana (USA)
- Univ. of Alberta, Edmonton (Canada)
The elastic properties of a solid solution consisting of 59 mole percent pyropic garnet and 41% Mg{sub 4}Si{sub 4}O{sub 12}-majorite (a high-pressure form of pyroxene), have been measured by Brillouin spectroscopy under ambient conditions. Values of the adiabatic bulk modulus, K{sub s} = 164 {plus minus} 15 GPa, and shear modulus, G = 89.4 {plus minus} 3.7 GPa, are similar to those for low-pressure aluminosilicate garnets. The enstatite-majorite reaction is characterized by a large (49%) increase in K{sub s} and a much smaller (13%) increase in G. The properties of low-pressure garnets suggest that the contrast in shear moduli for this reaction is probably larger in Ca-rich systems. Taken at face value, the STP properties of these phases imply that large quantities of Ca-rich clinopyroxene are needed in order to satisfy seismologically determined shear modulus gradients in the transition zone. This suggestion is, however, subject to considerable uncertainties in the pressure and temperature derivatives of elastic properties for mantle minerals, and the velocity structure of the transition zone.
- OSTI ID:
- 5639749
- Journal Information:
- Geophysical Research Letters (American Geophysical Union); (USA), Journal Name: Geophysical Research Letters (American Geophysical Union); (USA) Vol. 17:11; ISSN 0094-8276; ISSN GPRLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
152002* -- Geothermal Data & Theory-- Properties of Minerals & Rocks
58 GEOSCIENCES
580000 -- Geosciences
ALKALINE EARTH METAL COMPOUNDS
BRILLOUIN EFFECT
COHERENT SCATTERING
DATA ANALYSIS
DISPERSIONS
EARTH MANTLE
ELASTICITY
GARNETS
GEOPHYSICAL SURVEYS
MAGNESIUM COMPOUNDS
MAGNESIUM SILICATES
MECHANICAL PROPERTIES
MINERALS
MIXTURES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
QUANTITY RATIO
SCATTERING
SEISMIC SURVEYS
SILICATES
SILICON COMPOUNDS
SOLID SOLUTIONS
SOLUTIONS
SPECTROSCOPY
SURVEYS
TENSILE PROPERTIES
THERMODYNAMIC PROPERTIES