Mechanical data and microstructures of simulated calcite fault gouge sheared at 550°C

Verberne, Berend Antonie; Chen, Jianye; Pennock, Gillian;

2017-10 || GFZ Data Services

The largest magnitude earthquakes nucleate at depths near the base of the seismogenic zone, near the transition from velocity weakening frictional slip to velocity strengthening ductile flow. However, the mechanisms controlling this transition, and relevant to earthquake nucleation, remain poorly understood. Here we present data from experiments investigating the effect of slip rate on the mechanical properties and microstructure development of simulated calcite fault gouge sheared at ~550°C, close to the transition from (unstable) velocity weakening to (stable) velocity strengthening behaviour, reported by Verberne et al. (2015).



We conducted experiments at a constant effective normal stress (σneff) of 50 MPa, as well as σneff-stepping tests employing 20 MPa ≤ σneff ≤ 140 MPa, at constant sliding velocities (v) of 0.1, 1, 10, or 100 µm/s. Samples sheared at v ≥ 1 µm/s showed a microstructure characterized by a single, 30 to 40 μm wide boundary shear, as well as a linear correlation of shear strength (τ) with σneff. Remarkably, electron backscatter diffraction mapping of polygonal shear band grains demonstrated a crystallographic preferred orientation. By contrast, samples sheared at 0.1 µm/s showed a microstructure characterized by homogeneous deformation and plastic flow, as well as a flattening-off of the τ-σneff curve. Our results point to a strain rate dependent frictional-to-viscous transition in simulated calcite fault gouge, and have important implications for the processes controlling earthquake nucleation at the base of the seismogenic zone.



Originally assigned keywords

Corresponding MSL vocabulary keywords

MSL enriched keywords

Originally assigned sub domains
  • rock and melt physics
MSL enriched sub domains
  • microscopy and tomography
  • analogue modelling of geologic processes
  • rock and melt physics
  • geochemistry
Source http://dx.doi.org/doi:10.5880/fidgeo.2017.012
Source publisher GFZ Data Services
DOI 10.5880/fidgeo.2017.012
License CC BY 4.0
Authors
  • Verberne, Berend Antonie
  • 0000-0002-1208-6193
  • High Pressure & Temperature Laboratory, Utrecht University
References
  • Niemeijer, A. (2017). Hydrothermal Friction data of gouges derived from the Alpine Fault [Data set]. GFZ Data Services. https://doi.org/10.5880/ICDP.5052.002
  • 10.5880/ICDP.5052.002
  • Cites
  • Verberne, B. A., Niemeijer, A. R., De Bresser, J. H. P., & Spiers, C. J. (2015). Mechanical behavior and microstructure of simulated calcite fault gouge sheared at 20–600°C: Implications for natural faults in limestones. Journal of Geophysical Research: Solid Earth, 120(12), 8169–8196. Portico. https://doi.org/10.1002/2015jb012292
  • 10.1002/2015JB012292
  • References
  • Niemeijer, A. R., Boulton, C., Toy, V. G., Townend, J., & Sutherland, R. (2016). Large‐displacement, hydrothermal frictional properties of DFDP‐1 fault rocks, Alpine Fault, New Zealand: Implications for deep rupture propagation. Journal of Geophysical Research: Solid Earth, 121(2), 624–647. Portico. https://doi.org/10.1002/2015jb012593
  • 10.1002/2015jb012593
  • References
  • Verberne, B. A., Chen, J., Niemeijer, A. R., de Bresser, J. H. P., Pennock, G. M., Drury, M. R., & Spiers, C. J. (2017). Microscale cavitation as a mechanism for nucleating earthquakes at the base of the seismogenic zone. Nature Communications, 8(1). https://doi.org/10.1038/s41467-017-01843-3
  • 10.1038/s41467-017-01843-3
  • IsSupplementTo
Contact
  • Verberne, Berend Antonie
  • High Pressure and Temperature Laboratory, Utrecht University
  • b.a.verberne@uu.nl
Citation Verberne, B. A., Chen, J., & Pennock, G. (2017). Mechanical data and microstructures of simulated calcite fault gouge sheared at 550°C [Data set]. GFZ Data Services. https://doi.org/10.5880/FIDGEO.2017.012