EGU2020-16979
https://doi.org/10.5194/egusphere-egu2020-16979
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Antigorite deformation and dehydration-induced compaction

Nicolas Brantut1, Emmanuel David1, Lars Hansen2, Greg Hirth3, Jean Sulem4, and Ioannis Stefanou4
Nicolas Brantut et al.
  • 1Department of Earth Sciences, University College London, London, UK
  • 2Department of Earth and Environmental Sciences, University of Minnesota, Twin Cities, MN, USA
  • 3Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
  • 4Ecole des Ponts Paris Tech, Marne-La-Vallée, France

Antigorite is a key constituent of subducted slabs, and its dehydration is thought to be responsible for the generation of intermediate-depth earthquakes. The mechanical behaviour of antigorite at elevated pressure and temperature remains difficult to constrain experimentally: intracrystalline slip systems are hard to activate under typical laboratory timescales and microstructures do not always provide unambiguous evidence for dislocation creep. Here, we present recent laboratory data showing that antigorite might deform due to intracrystalline frictional slip and delamination, at least in the low temperature regime (<400°C). This behaviour is typical of the semi-brittle regime. Based on a time-independent rheology including friction and potential compaction at elevated pressure, we formulate a model for coupled deformation and dehydration of antigorite. We show that a pore pressure and compaction localisation instability can develop when the net volume change associated with the reaction is negative, i.e., at intermediate depth in subduction zones. Unstable compaction and fluid pressure build-up may provide a mechanism for the nucleation of intermediate-depth earthquakes.

How to cite: Brantut, N., David, E., Hansen, L., Hirth, G., Sulem, J., and Stefanou, I.: Antigorite deformation and dehydration-induced compaction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16979, https://doi.org/10.5194/egusphere-egu2020-16979, 2020

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