Geoscience Reference
In-Depth Information
Fig. 4.5
A schematic diagram
showing a possible mechanism of
shear localization by grain-size
reduction due to dynamic
recrystallization. (a) A schematic
drawing of a microstructure of
dynamically deforming rock after a
stress pulse. Upon a stress pulse,
small dynamically recrystallized
grains are formed along pre-existing
grain-boundaries. (b) A deformation
mechanism map (on a grain-size
versus stress) showing the
dominant mechanisms of
deformation together with the
grain-size versus stress relationship
for dynamically recrystallized
grains. Upon a stress pulse, small
grains are formed (A: initial stress
and grain-size, B: grain-size after
dynamic recrystallization). If the
size of new grains is smaller than
the mechanism boundary between
diffusion and dislocation creep,
then that region is weak and
promotes shear localization. At
relatively low temperatures, the
mechanism boundary moves to
high stress, coarse-grain region and
shear localization is likely.
(a)
mechanism boundary
recrystallize grain-size
versus stress relation
dislocation creep
B
A
diffusion creep
Lf
Li
grain-size
(b)
