Self‐consistent subduction initiation induced by mantle flow |
| |
| Authors: | Gang Lu Boris JP Kaus Liang Zhao Tianyu Zheng |
| |
| Affiliation: | 1. Key Laboratory of the Earth's Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China;2. Department of Earth Sciences, University of Bergen, Bergen, Norway;3. Institute of Geosciences, Johannes Gutenberg University Mainz, Mainz, Germany;4. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China |
| |
| Abstract: | Mantle circulation in planets with strongly temperature‐dependent viscosity results in stagnant‐lid convection. It is fundamental to understand how this stagnant‐lid regime can change into a plate‐like convection regime as on the present‐day Earth. Here, we use 2D numerical models to study subduction initiation from an initial stagnant lid with laboratory‐consistent parameters and without pre‐existing weak zones or kinematic boundary conditions. Our results show that subduction can be initiated dynamically as a result of a thermal localization instability. The lithosphere may deform in a stagnant‐lid mode, an un‐necking mode, a symmetric‐subduction mode or an asymmetric‐subduction mode. The asymmetric‐subduction mode occurs only for relatively large friction angles and moderate thermal ages, and the presence of heterogeneities increases the parameter space of this mode. The limited parameter space might explain why only the present‐day Earth has plate tectonics, and suggests that the initiation of plate tectonics is more difficult than previously anticipated. |
| |
| Keywords: | |
|
|
