Elasticity of polycrystalline pyrope (Mg3Al2Si3O12) to 9 GPa and 1000 degrees C | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Elasticity of polycrystalline pyrope (Mg3Al2Si3O12) to 9 GPa and 1000 degrees C

Type de publication:

Journal Article

Source:

Physics of the Earth and Planetary Interiors, Volume 155, Ticket 3-4, p.179-190 (2006)

ISBN:

0031-9201

Numéro d'accès:

0002381765-0001

URL:

http://www.sciencedirect.com/science/journal/00319201

Mots-clés:

Multi-anvil-apparatus; single-crystal-elasticity; equation-of-state; high-pressure; wave-velocities; transition-zone; solid-solution; upper-mantle; ultrasonic-interferometry; sound-velocities

Résumé:

Acoustic wave velocities for synthetic polycrystalline pyrope (Mg3Al2Si3O12) were measured to 9 GPa and temperatures up to 1000 degrees C by ultrasonic interferometry combined with energy-dispersive synchrotron X-ray diffraction in a cubic-anvil DIA-type apparatus (SAM-85). Specimen lengths at high pressures (P) and temperatures (7) are directly measured by X-radiographic methods. Elastic wave travel times and X-ray diffraction data were collected after heating and cooling at high pressures to minimize effect of non-hydrostatic stress on the measurements. A linear fit to the high P and T data set yields the elastic bulk and shear moduli [K-S = 175 (2) GPa; G = 91 (1) GPa] and their pressure and temperature derivatives [K'(S) = 3.9 +/- 0.3; G' = 1.7 +/- 0.2 and (delta K-S/delta T)(P) = -18 (2) MPa/K; (delta G/delta T)(P) = -10 (1) MPa/K]. In a separate analysis, the pressure-volume-temperature data collected during these acoustic experiments were fit to a high temperature Birch-Murnaghan (HTBM) equation [with K' fixed at 3.9] and to each isothermal P-V-T data yielding (delta K-T/delta T)(P) = -22 (2) MPa/K and (delta K-T/delta T)(P) = -20 (5) MPa/K, respectively. Comparison of Py100 data with those other Py-Mj compositions indicates that the thermo elastic properties are insensitive to majorite content in the garnet along the pyrope-majorite join. (c) 2005 Elsevier B.V. All rights reserved.

Notes:

Delaware State Univ, Dept Phys & Pre Engn, Dover, DE 19901 USA; Stony Brook Univ, Inst Mineral Phys, Stony Brook, NY 11974 USA; Stony Brook Univ, Dept Geosci, Stony Brook, NY 11974 USA; Lab Phys Globe Paris, Dept Geomat, Paris, France; Los Alamos Natl Lab, Los Alamos, NM 87545 USAArticleEnglish