Subduction initiation and the (ultra)high-pressure rock cycle

Subduction zones are one of the main features of plate tectonics, they are essential for burial-exhumation cycling of rocks and are often a key player during mountain building. However, several processes related to subduction zones remain elusive, such as the initiation of subduction or the exhumation of (ultra)high-pressure rocks. Deterministic models are useful tools to investigate and better understand geodynamic processes. These mathematical models integrate observational and experimental data with the fundamental laws of physics and thermodynamics. I present numerical solutions of two-dimensional petrological-thermo-mechanical models for a large-scale (660 km deep) and long-term (>100 Myrs) geodynamic cycle of subsequent extension, cooling with no far-field deformation and convergence. During convergence, the models predict a continuous evolution from horizontally-forced subduction initiation at a passive margin to burial and exhumation of (ultra)high-pressure rocks. I discuss the importance of modelling large-scale and long-term geodynamic cycles for the study of smaller-scale and short-term geodynamic processes, such as subduction initiation or rock exhumation. Furthermore, I discuss the processes of subduction initiation and rock exhumation predicted by the models. Finally, I compare the model results with force estimates from natural observations and pressure-temperature-age data from exhumed metamorphic rocks. Particularly, I apply the model results to the western Alpine orogeny.