Abstract
The formation of localized shear zones is important for understanding many local and global processes in geodynamics. We have developed a self-consistent thermal-mechanical model together with a rheology which depends on temperature, strain-rate and grain-size distribution. The grain-size distribution has contributions from both dynamic recrystallization and grain-growth processes, and is governed locally by a nonlinear ordinary differential equation. A one-dimensional model with 104 points is employed to resolve all of the scales involving grain-size and temperature. We found that grain-growth inhibits the development of shear zones, and that there is a delicate interplay between viscous heating and grain-growth process in determining whether narrow fault zones are developed quickly. For realistic parameters of rheology and grain-boundary processes for wet olivine, the magnitude of the rate of grain-growth is crucial to determine whether shear zones are stable or unstable at temperature T ≃ 1000 K or shear stress a ≃ 100 MPa.
Original language | English (US) |
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Article number | 97GL02648 |
Pages (from-to) | 2523-2526 |
Number of pages | 4 |
Journal | Geophysical Research Letters |
Volume | 24 |
Issue number | 20 |
DOIs | |
State | Published - 1997 |