Compressional behavior of omphacite to 47 GPa
- Univ. of Hawaii at Manoa, Honolulu, HI (United States); Carnegie Institution of Washington
- Univ. of Hawaii at Manoa, Honolulu, HI (United States)
Omphacite is an important mineral component of eclogite. Single crystal synchrotron X-ray diffraction data on natural (Ca,Na)(Mg,Fe,Al)Si2O6 omphacite have been collected at the Advanced Photon Source beamlines 13-BM-C and 13-ID-D up to 47 GPa at ambient temperature. Unit cell parameter and crystal structure refinements were carried out to constrain the isothermal equation of state and compression mechanism. The 3rd order Birch-Murnaghan equation of state (BM3) fit of all data gives Vo = 423.9(3) Å3, KTo = 116(2) GPa and KTo’ = 4.3(2). These elastic parameters are consistent with the general trend of the diopside-jadeite join. The eight-coordinated polyhedra (M2 and M21) are the most compressible, and contribute to majority of the unit cell compression, while the SiO4 tetrahedra (Si1 and Si2) behave as rigid structural units and are the most incompressible. Axial compressibilities are determined by fitting linearized BM3 equation of state to pressure dependences of unit cell parameters. Throughout the investigated pressure range, the b-axis is more compressible than the c-axis. Here, the axial compressibility of the α-axis is the largest among the three axes at 0 GPa, yet it quickly drops to the smallest at pressures above 5 GPa, which is explained by the rotation of the stiffest compression axis toward the a-axis with the increase of pressure.
- Research Organization:
- Carnegie Institution of Washington, Washington, D.C. (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- NA0002006
- OSTI ID:
- 1364640
- Journal Information:
- Physics and Chemistry of Minerals, Journal Name: Physics and Chemistry of Minerals Journal Issue: 10 Vol. 43; ISSN 0342-1791
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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