2024-03-29T13:56:03Zhttp://doidb.wdc-terra.org/oaip/oaioai:doidb.wdc-terra.org:63322020-09-26T12:19:46ZDOIDBDOIDB.FID
10.5880/fidgeo.2017.012
Verberne, Berend Antonie
0000-0002-1208-6193
High Pressure & Temperature Laboratory, Utrecht University
Chen, Jianye
0000-0002-5973-5293
High Pressure & Temperature Laboratory, Utrecht University
Pennock, Gillian
7006507017
Structural Geology & Tectonics, Utrecht University
Mechanical data and microstructures of simulated calcite fault gouge sheared at 550°C
GFZ Data Services
2017
EPOS
multi-scale laboratories
rock and melt physical properties
European Plate Observing System
Verberne, Berend Antonie
0000-0002-1208-6193
High Pressure & Temperature Laboratory, Utrecht University
Chen, Jianye
0000-0002-5973-5293
High Pressure & Temperature Laboratory, Utrecht University
Pennock, Gillian
7006507017
Structural Geology & Tectonics, Utrecht University
Experimental rock deformation/HPT-Lab (Utrecht University, The Netherlands)
Utrecht University, The Netherlands
2017-10-12
en
10.5880/ICDP.5052.002
10.1002/2015JB012292
10.1002/2015jb012593
10.1038/s41467-017-01843-3
364269060 Bytes
2 Files
application/zip
application/pdf
CC BY 4.0
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.