Numerical Modeling of Thermal Structure for the Continental Subduction Zones

The thermal structure of subduction zone is one of the most important factors controlling the evolution of subduction plate. Previous studies on the thermal structure of oceanic subduction zones have been carried out by establishing analytical and numerical models. It is found that the age and velocity of the subduction plate are the key factors affecting the thermal structure of the subduction zones. In order to further understand the thermal structure of the continental subduction zone,especially to understand the difference between the numerical model results and petrological results,we established two-dimensional numerical kinematic and geodynamic models of the continental subduction zone to study its thermal structure evolution. The model results show that if the subduction velocity and dip angle of the continental plate are the same as those of the oceanic plate,lower initial temperature causes the continental subduction zone to be colder than the oceanic subduction zone. However,when the initial temperature of the continental plate is high,the subduction velocity is super slow and the heat generation of radioactive elements in the continental crust is taken into account,the thermal structure of the continental subduction zone obtained by the model can explain the hot subduction temperature obtained from high-pressure and ultra-high-pressure metamorphic rocks. On the other hand,if there is dynamic decoupling between the subduction plate and the overlying plate,the hot subduction temperature can also be obtained.