The role of hydration-induced processes in the deformation of the North China craton

Numerous previous studies have been conducted in the North China Craton to investigate its anomalously thin lithosphere, high magmatism, and extensional tectonics along its eastern margin. Based on petrological analyses it has been suggested that the cratonic mantle lost its root (~100 km) with multiple tectonic processes during the late Jurassic – Early Cretaceous. The weakening and erosion of the North China craton is often attributed to its high water content and lower viscosity of the lithosphere associated with the movement and position of the Paleo-Pacific plate. However, other mechanisms and control parameters for the craton destruction have been proposed, and the thinning of the North China craton remains an enigmatic process.

To have a better understanding of the dynamics of the lithospheric deformations beneath the North China Craton that changes over time, we conducted a series of 2D geodynamic models. Specifically, we investigate the impact of hydration-induced processes on the lithosphere and the overriding plate and focus on parameters such as external tectonic forcing, the rheology and the strength of the overriding plate. Moreover, the effect of the angular position of the oceanic plate, and the existence of the mid-lithosphere discontinuities was also examined. Our results reveal that the destruction of North China Craton is more complex and heterogeneous than is often assumed in modelling studies. Furthermore, we find that without significant weakening, the mantle lithosphere is unlikely to delaminate. Extensive hydrous weakening may account for this, but external tectonic forcing in combination with non-linear rheology and eclogitization of the lower crust may have played an important role too.