Dynamic cause of marginal lithospheric thinning and implications for craton destruction: a comparison of the North China, Superior, and Yilgarn cratons

Abstract

We present a comparative tectonic analysis of the North China Craton (NCC), which has lost parts of its root, with the Yilgarn and Superior cratons, which preserve their roots. We compare the geophysical structure and tectonic histories of these cratons to search for reasons why some cratons lose their roots, while others retain them. Based on the comparison and analysis of geological, geophysical, and geochemical data, it is clear that the lithospheric thinning beneath craton margins is a common phenomenon, which may be caused by convergence between plates. However, craton destruction is not always accompanied by lithospheric thinning, except for cratons that suffered subduction and collision from multiple sides. The Western Block (also known as the Ordos Block) of the NCC, Yilgarn and Superior cratons have not experienced craton destruction; the common ground among them is that they are surrounded by weak zones (e.g., mobile belts or orogens) that sheltered the cratons from deformation, which contributes greatly to the long-term stability of the craton. Subduction polarity controlled the water released by the subducting plate, and if subducting plates dip underneath the craton, they release water that hydroweakens the overlying mantle, and makes it easy for delamination or sub-continental lithospheric mantle erosion to take place in the interior of the craton. Thus, subduction polarity during convergence events is an important element in determing whether a craton retains or loses its root.