Elasticity of Polycrystalline Pyrope (Mg3Al2Si3O12) to 9 GPa and 1000°C
Acoustic wave velocities for synthetic polycrystalline pyrope (Mg3Al2Si3O12) were measured to 9 GPa and temperatures up to 1000 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 (T) 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 [KS = 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 ({partial_derivative}KS/{partial_derivative}T)P = -18 (2) MPa/K; ({partial_derivative}G/{partial_derivative}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 ({partial_derivative}KT/{partial_derivative}T)P = -22 (2) MPa/K and ({partial_derivative}KT/{partial_derivative}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.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 959951
- Report Number(s):
- BNL--82937-2009-JA
- Journal Information:
- Physics of the Earth and Planetary Interiors, Journal Name: Physics of the Earth and Planetary Interiors Vol. 155; ISSN 0031-9201; ISSN PEPIAM
- Country of Publication:
- United States
- Language:
- English
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