0000000000886855
AUTHOR
Tianyu Zheng
Strong intracontinental lithospheric deformation in South China: Implications from seismic observations and geodynamic modeling
Abstract Classical plate tectonics theory predicts concentrated deformation at plate boundaries and weak deformation within plates. Yet, the existence of intracontinental orogens shows that highly deformed regions can occur within continental plates, which is geodynamically incompletely understood. Shear wave splitting measurements in South China show belt-parallel (i.e. NE–SW) fast directions beneath the Wulingshan-Xuefengshan Belts, while no dominant fast direction is found in the cratonic Sichuan Basin. Tomographic studies in the mantle in the same area show that the thickness of lithosphere beneath the intracontinental orogen is larger than that beneath the cratonic Sichuan Basin. In or…
Self-consistent subduction initiation induced by mantle flow
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…