Figure 4

a) Second Invariant Deviatoric Strain Rate (high-to-low corresponds to blue-to-red) in the lithosphere in the vicinity of the double subduction zone.

 

b) Second Invariant Deviatoric Stress (high-to-low corresponds to blue-to-red) and Velocity vectors in the lithosphere in the vicinity of the double subduction zone.

 

c) Model geometry and rheological properties of crust (green upper layer), `fluid' mantle (grey) and mantle lithosphere (other colours). Weak zone for left/right subduction is blue/red. All units SI. phi = Coulomb internal angle of friction, c = cohesion, rho = density, µ = viscosity.

Figure 4. Low resolution (81 x 161 Eulerian grid) `double subduction' model. Initial geometry is the same as that shown in figure 3 except a second, but oppositely dipping, weak zone was added to the right of the one shown. Figure shows Eulerian material distribution after 150 km of convergence from both left and right boundaries, v = 1 x 10-9 m/s (3.15 cm/yr). Left and right boundaries below lithosphere have small `leakage' flux to balance lithospheric influx. Model materials are very simple but the result illustrates the large deformation capability of OPALE and the Lagrangian tracking and regridding of the materials. Model is illustrative only and not intended to demonstrate physics of subduction. Note deflection of free surface.

Back to Lithoprobe Supporting Geoscience Proposal, November 1998