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Abstract Novel fluid medium pressure cells were used to deform antigorite under constant stress creep conditions at low temperature, low strain rate (10−9 − 10−41/s), and high pressure (1 GPa) in a Griggs‐type apparatus. Antigorite cores were deformed at constant temperatures between 75°C and 550°C, by applying 8–12 stress‐strain steps per temperature. The microstructures of deformed samples share features documented in previous work (e.g., shear microcracks), and highlight the importance of basal shear and kinks to antigorite plasticity. Rheological data were fit with a low temperature plasticity law, consistent with a deformation mechanism involving large lattice resistance. When applied at geologic stresses and strain rates, the extrapolated viscosity agrees well with predictions based on subduction zone thermal models.
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This content will become publicly available on February 1, 2026
Large volume torsion (LVT) apparatuses for rock deformation at high pressure and temperature
Laboratory studies of rock rheology rely on purpose-built devices that can apply planetarily relevant pressures, temperatures, and non-hydrostatic stresses. Generating these pressures and stresses requires the application of large forces over small specimen areas. However, because rocks are generally polymineralic and deformation microstructures form across many length scales, it is advantageous to study relatively large (millimetric) specimens. In addition, many microstructures continue to evolve with progressive strain, so it is vital that some apparatus are able to generate enough shear strain to study these deformation phenomena. This contribution describes two new rock deformation apparatus—the Large Volume Torsion apparatus—at Washington University in St. Louis, which are capable of deforming geological specimens at high pressure and temperature (P = 3 GPa; T = 1800 K). Deformation is imposed in a torsional geometry, which enables the generation of extremely large shear strains (γ > 100) relevant to Earth’s plate boundaries and convecting mantle. A large specimen (diameter up to 4.2 mm) permits detailed postmortem microstructural analysis. Apparatus design, calibration, experimental procedures, and some examples of applications are reviewed.
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- Award ID(s):
- 2149427
- PAR ID:
- 10580792
- Publisher / Repository:
- NSF-PAR
- Date Published:
- Journal Name:
- Review of Scientific Instruments
- Volume:
- 96
- Issue:
- 2
- ISSN:
- 0034-6748
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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