Flat Slab Formation and Its Consequences
Flat-slab subduction is an important tectonic process that greatly shapes the Earth’s surface geology. However, both the causes and the consequences of flat-slab subduction remain unclear. We simulate the post-100 Ma subduction history below South America using 4-D geodynamic models by progressively incorporating plate kinematics, seafloor ages and key tectonic features including the buoyant oceanic crust, continental cratons, oceanic plateaus. Our model reveals the distinct roles of seafloor age, the continental cratons as well as the oceanic plateaus in reducing the slab dip angle. The best-fit model not only provides a good match to both the upper mantle Benioff zones and lower mantle tomography, but also explains the abnormal geological and seismological features associated with the flat slabs that would influence the continental evolution in the long term. See Hu et al. (2016) and Hu and Liu (2016).
