4 4

674

AppendixA. Supplementary materials

Fits

p

q

σP0

A

(GPa)

(s−1 .MPa−2 )

E∗

V∗

(kJ.mol−1 ) (cm3 .mol−1 )

Fit1

3/4

4/3

9.3 ± 0.7

7.8 ± 0.6 × 10−1

233 ± 57

9.5 ± 2.3

Fit2

1

1

7.8 ± 1.1

3.7 ± 0.6 × 10−1

171 ± 62

7.2 ± 1.3

Fit3

0.5

1

8.5 ± 1.4

1.9 ± 0.2 × 10−1

235 ± 33

9.3 ± 3.1

Fit4

1

2

12.1 ± 0.3

1.8 ± 0.2 × 10−2

177 ± 76

4.0 ± 2.8

Fit5

2/3

2

12.9 ± 0.9

3.3 ± 0.1 × 10−4

209 ± 72

7.7 ± 4.0

Fit6

0.5

2

14.2 ± 0.9

3.3 ± 0.1 × 10−4

280 ± 57

10.0 ± 1.6

4/3

7.4 ± 0.5

2.2 ± 0.7 × 10−2

232 ± 60

1.6 ± 1.7

Fit7a 3/4 a

β = 0.09 ± 0.02. Table A.3: Fits obtained for different fixed values of p and q.

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Figure A.12: Evolution of stress with temperature for pressures of 0 (in blue), 5 (green), 10 (yellow) and 15 GPa (red) using low-temperature flow laws with (continuous lines) and without (dashed lines) a pre-exponential term σ n , p = 0.5, q = 1 and : a. an activation volume of 5 cm3 .mol−1 and no pressure dependence of the Peierls stress, or b. a Peierls stress function of pressure as defined by Frost and Ashby (1982) and no activation volume. The graph c. shows the combined effect of the pressure dependence of both the Peierls stress and the activation volume.

45

Figure A.13: Geotherm across a 50 km-thick oceanic slab assuming a slope of 60 degrees and a temperature at the bottom of the lithosphere of 1200°C. The dark curve indicates the profile of minimal temperature in the slab.

46