Stress-induced amorphization triggers deformation in the lithospheric mantle

Abstract

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The Potential for Low‐Grade Metamorphism to Facilitate Fault Instability in a Geothermal Reservoir

“…Ep and Cl are likely to be heterogeneously distributed within fault zones and along fracture planes since metamorphism results from interaction with heterogeneously distributed groundwaters (Samae et al., 2021; Spinelli & Wang, 2009). Rock cores sampled from 4.2 km in the Pohang geothermal reservoir (Kwon et al., 2019) indicate that the Pohang Gra is highly fractured–and correspondingly the fault zone is likely highly permeable (Caine et al., 1996).…”

Quartz rheology constrained from constant-load experiments: Consequences for the strength of the continental crust

“…The presence of H 2 O and dissolution-precipitation may weaken the grain boundary region and promote strain accommodation by sliding along boundaries. Recently, a comparable mechanism was inferred in olivine (Samae et al, 2021), where grain boundary amorphization promotes GBS, leading to the viscosity drop in mantle rocks. In analogy to ice (and perhaps olivine), we propose that strain is achieved in coarse-grained wet quartzite by dislocation creep (mainly glide), accommodated by grain boundary processes including DPC and GBS.…”

Resolving puzzles of the phase-transformation-based mechanism of the strong deep-focus earthquake

“…Orthorhombic olivine has only three independent slip systems set, i.e., less than five required for the accommodation of arbitrary homogeneous deformation. That is why other mechanisms like grain-boundary migration through disclination motion 35 , amorphization 36 , dislocation climb, diffusive creep, and other isotropic mechanisms with linear flow rule 37 , 38 supplement dislocation plasticity and control strain rate. Less than 40% of olivine aggregate strain at high temperatures may be accommodated by dislocation activity.…”