Numerical modeling of north china craton Thinning and destruction.

 

The North China Craton is located on the Eurasian continental margin. Since the Mesozoic, the Izanagi and Pacific plates are subducting westward with the trench retreating eastward over time. This process is accompanied by extensive magmatism, development of rift basins, and the formation of the Japan sea. The lithosphere of the North China Craton, which is about 220 km thick, gradually becomes thinner from west to east down to around 60-80 km.

 

Due to extensive magmatism between 140-120Ma, we believe that the North China Craton was positioned at the back-arc area of the Eurasian continental margin where the Izanagi plate currently subducts, and the trench gradually migrated eastward. We assume that the subduction event formed a large-scale high-temperature weak zone, similar to the high-temperature back-arc region mentioned in (Currie & Hyndman, 2006). By using thermo-mechanical modeling, we simulated the Craton break-up process. Following a continuous eastward extension model characterized by normal faulting and lithospheric thinning, we approximated the observed lithospheric variations. If the extension of the Japan sea is not considered, lithospheric thickness was simulated to decrease from 220 km to 60 km eastward. Within 600 km of tension, continuous lithospheric thinning will eventually lead to the formation of oceanic crust (Japan sea).

        We tested the mechanism affecting lithosphere thinning and found that a large-scale initial high-temperature weak zone and a low-viscosity mantle (with a large amount of fluid participation) are the key factors for the break-up of the North China craton.