Page 315 - Global Tectonics

298 CHAPTER 10

Crust Mantle 6 Crust Mantle 6

5 5
Buoyancy force 4 3 Distance (km/100) Tectonic force 4 3 Distance (km/100)

2 2 Carnegie R. 15 14 15 14 15 14 15 14 15 14
Slip layer 1 1 13 12 13 12 13 12 13 12 13 12

0 0 Nazca. R. 11 11 11 11 11
1.5 1 0.5 0 0.5 1.5 1 0.5 0 0.5 10 10 10 10 10

Depth (km/100)
Depth (km/100)
Profile # Nazca Plate
9 9 9 9 9
12 8 8 8 8 8
Null velocity B.C.
Crust Mantle 7 7 7 7 7
10 J.F.R. 6 5 6 5 6 5 6 5 6 5

Deformable grid Asthenosphere no-shear B.C. 8 6 Distance (km/100) Taitao T.J. 4 3 2 4 3 2 4 3 2 4 3 2 4 3 2 (a) Trench topography for 15 profiles of the Andes between 3°N and 56°S showing dip of the Benioff zone at 1:1 scale (left). Bathymetric profiles at right show a vertical exaggeration of 10. (b) Viscous model of trench topography showing mesh grid and boundary conditions (B.C.). Dynamic equilibrium of the trench is controlled by competing buoyancy (top-right) and tectonic (lower-right) forces. Veloci

4 1 1 1 1 1 Antarctic Plate viscosity for a layer of 10 km thickness (all images modified from Yáñez & Cembrano, 2004, by permission of the American Geophysical Union. Copyright ©
a b c d e
50 dip 0 40 20 dip 0 50 (Ma) 0 10 5 (cm a ) 0 0.02 0.01 (10 Pa s) 0
velocity B.C.
Buoyancy Force Convergence 2 (c) 100–300 km 0–100 km age 1 Convergence 22 Slip visc.

0
2 1 0 1
(b) Depth (km/100)

Profile: 15 Profile: 14 Profile: 13 Profile: 12 Profile: 11 Profile: 10 Profile: 9 Profile: 8 Profile: 7 Profile: 6 Profile: 5 Profile: 4 Profile: 3 Profile: 2 Profile: 1

100 km 2004 American Geophysical Union). T.J., triple junction; J.F.R., Juan Fernández Ridge.

3 N 0 S 4 S 7 S 11 S 15 S 18 S 21 S 24 S 28 S 33 S 35 S 41 S 46 S 52 S 10 km

100 km 100 km

Figure 10.8

(a)