Thermal equation of state of omphacite
Thermal equation of state of omphacite
American Mineralogist (January 2003) 88 (1): 80-86
- basalts
- chain silicates
- clinopyroxene
- crystal chemistry
- equations of state
- experimental studies
- high temperature
- igneous rocks
- lattice parameters
- mid-ocean ridge basalts
- omphacite
- pyroxene group
- silicates
- temperature
- thermal properties
- thermoelastic properties
- unit cell
- volcanic rocks
- X-ray diffraction data
In-situ synchrotron X-ray diffraction experiments were conducted using the MAX-III multi-anvil press of KEK on an omphacite (Di (sub 63) Jd (sub 37) ), for which Di = Ca(Mg,Fe)Si (sub 2) O (sub 6) and Jd = NaAlSi (sub 2) O (sub 6) . Pressure-volume-temperature data were collected at up to 10 GPa and 1000 K. A fit to the high-temperature Birch-Murnaghan equation of state yielded an isothermal bulk modulus K (sub T0) = 126(1) GPa, an assumed pressure derivative of the bulk modulus K' (sub T) = 4.0, a temperature derivative of the bulk modulus (theta K (sub T) /theta T) (sub P) = -0.015(4) GPa/K, and a volumetric thermal expansivity alpha = 2.2(1)X10 (super -5) K (super -1) , when the equation of state of NaCl by Brown (1999) is adopted for the pressure scale. The derived K (sub T0) value is consistent with the linear interpolations from K (sub T0) values for diopside and jadeite in the literature.
