Thermal conductivity and sound velocity of antigorite at high pressure using time-domain thermoreflectance
Abstract
We measure the thermal conductivity and compressional wave velocity of antigorite at room temperature and up to 13 GPa. Antigorite is a serpentine mineral (Mg6Si4O10(OH)8) of high-temperature form having a wavy structure and it has a wide stability field (e.g., up to 720⁰C at 2 GPa or 620⁰C at 5 GPa), which is a key material for understanding slab subduction, deep earthquake and volcanic processes in the mantle wedge where fluids from the dehydrating oceanic crust interact with the mantle. The mineral phases, chemical compositions, and crystal orientations of the antigorite were analyzed using Raman spectroscopy, energy-dispersive spectroscopy, and electron backscattered diffraction, respectively. The measurements of thermal conductivities and sound velocities of antigorite with different crystal orientations were carried out by time-domain thermoreflectance (TDTR). At P<7 GPa, thermal conductivity becomes more anisotropic with increasing pressure but becomes more isotropic in elastic property between b and c-axis. We also discuss the lattice internal rearrangement may induce over three times increase in thermal conductivity at 7 GPa ( 210 km depth) which would enhance larger heat flux along b-axis in the serpentinized slab. Thus, it gives new insights into the potential influence of thermal conductivity anisotropy on the mineral dehydration processes in the subduction zone.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMMR11A2363C
- Keywords:
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- 3919 Equations of state;
- MINERAL PHYSICSDE: 3924 High-pressure behavior;
- MINERAL PHYSICSDE: 3944 Shock wave experiments;
- MINERAL PHYSICSDE: 3994 Instruments and techniques;
- MINERAL PHYSICS