Geoscience Reference
In-Depth Information
T (K)
1520 1500 1480
1460 1440
−
4.5
synthetic peridotite
CaTiO
3
s
d
=
8.2
m
m
6.2 MPa
In air
=
Q
=
731 kJ/mol
T
1473 K
P
=
300 MPa
d
=
17
μ
m
=
−
5.0
10
−
4
d
=
27.3
m
m
Q
=
803 kJ/mol
−
5.5
10
−
6
−
6.0
−
6.
6.5
10
1
10
2
6.6
6.7
6.8
6.9
7.0
10
4
/ T (K
−
1
)
(MPa)
s
(a)
(b)
olivine
Peierls mechanism
−
4.0
CoTiO
3
1491K
6.2MPa
−
4.5
10
3
−
5.0
m
=
2.1
−
5.5
10
2
−
6.0
Power-low creep
−
6.5
−
7.0
0.5
1.0
log d (
m
m)
1.5
2.0
500
1000
1500
temperature,
°
C
(c)
(d)
Fig. 4.8
(a) Dependence of strain-rate on temperature (CaTiO
3
perovskite data from (Li
et al
., 1996). (b) Dependence
of strain-rate on stress (lherzolite (dry), data from Zimmerman and Kohlstedt (2004). At small stresses, strain-rate is
linearly proportional to stress, whereas at high stresses, strain-rate is proportional to some power of stress (in this
case
ε
∝
σ
4
). (c) Dependence of strain-rate on grain-size (CaTiO
3
perovskite, data from (Li
et al
., 1996)).
m
is the
grain-size sensitivity (see Equation (4.14)).
m
2 (and stress dependence is linear) suggesting diffusion creep due to
volume diffusion. (d) Dependence of creep strength on temperature (olivine (dry), data from Evans and Goetze
(1979) showing two regimes of deformation: creep strength is highly sensitive to temperature at high temperature
but only weakly sensitive to temperature at low temperatures. Deformation mechanism in the low temperature
regime is likely the Peierls mechanism. (Numbers in the figure correspond to
log
10
ε
(
s
−
1
).)
∼
