Regional models of lithospheric subduction

Processes within subduction zones have major influence on the plate dynamics and mantle convection. Subduction process is influenced by a combination of many parameters and there is no simple global relationship between the resulting slab geometry and deformation and any specic subduction parameter. In the present work we perform a parametric study of the slab dynamics in a two-dimensional model with composite rheology including diffusion creep, dislocation creep and stress limiting rheology or Peierls creep. In our model, the separation of the subducting and overriding plates is ensured by a layer of a low viscosity material. We are particularly interested in the effect of the contact of subducting and overriding plate on the plate geometry in the upper mantle. We also study the influence of a surface boundary condition and the rheologic parameters of the plate. Model results are applied to the Kermadec subduction zone. We show that the model that best fits the observed morphology and plate velocities is the model with viscosity of crust of 1020 Pa.s, yield stress of 108 Pa and with a viscosity jump by a factor of 10 at the depth of 660 km