摘要：We present a semi-dynamic subduction zone model in a three-dimensional spherical shell.In this model, velocity is imposed on the top surface and in a small three-dimensional region around the shallow plate boundary while below this region, the slab is able to subduct under its own weight.Surface plate velocities are given by Euler’s theorem of rigid plate rotation on a sphere.The velocity imposed in the region around the plate boundary is determined so that mass conservation inside the region is satisfied.A kinematic trench migration can be easily incorporated in this model.As an application of this model, mantle flow around slab edges is considered, and we find that the effect of Earth curvature is small by comparing our model with a similar one in a rectangular box, at least for the parameters used in this study.As a second application of the model, mantle flow around a plate junction is studied, and we find the existence of mantle return flow perpendicular to the plate boundary.Since this model can naturally incorporate the spherical geometry and plate movement on the sphere, it is useful for studying a specific subduction zone where the plate kinematics is well constrained.
关键词：Semi-dynamic model ;subduction zone ;3D sphere ;mantle flow
