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Episodic slow slip hosted by talc-bearing metasomatic rocks: High strain rates and stress amplification in a chemically reacting shear zone
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  • William Floyd Hoover,
  • Cailey Condit,
  • Peter Carl Lindquist,
  • Amy Catherine Moser,
  • Victor E Guevara
William Floyd Hoover
University of Washington

Corresponding Author:[email protected]

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Cailey Condit
University of Washington
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Peter Carl Lindquist
University of Vermont
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Amy Catherine Moser
University of California, Santa Barbara
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Victor E Guevara
Amherst College
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Episodic tremor and slow slip (ETS) downdip of the subduction seismogenic zone are poorly understood slip behaviors of the seismic cycle. Talc, a common metasomatic mineral at the subduction interface, is suggested to host slow slip but this hypothesis has not been tested in the rock record. We investigate actinolite microstructures from talc-bearing and talc-free rocks exhumed from the depths of modern ETS (Pimu’nga/Santa Catalina Island, California). Actinolite deformed by dissolution-reprecipitation creep in the talc-free rock and dislocation creep ± cataclasis in the talc-bearing rock. This contrast results from stress amplification in the talc-bearing rock produced by high strain rates in surrounding weak talc. We hypothesize that higher strain rates in the talc-bearing sample represent episodic slow slip, while lower strain rates in the talc-free sample represent intervening aseismic creep. This work highlights the need to consider fluid-mediated chemical change in studies of subduction zone deformation and seismicity.