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The interaction of viscous heating with grain‐size dependent rheology in the formation of localized slip zones
Author(s) -
Kameyama Masanori,
Yuen David A.,
Fujimoto Hiromi
Publication year - 1997
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/97gl02648
Subject(s) - rheology , grain growth , grain size , shear (geology) , slip (aerodynamics) , materials science , grain boundary strengthening , recrystallization (geology) , geology , grain boundary , mechanics , thermodynamics , composite material , microstructure , physics , petrology
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 10 4 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 σ ≃ 100 MPa.