Modification of the Shallow Mantle Lithosphere during Craton Destruction

A craton refers to the ancient and stable core of a continent, and craton destruction is typically characterized by significant lithospheric thinning, internal deformation, and volcanic activity. One of the key features of craton destruction is the loss of the ancient lithospheric keel, which many researchers believe results from large-scale delamination along the mid-lithospheric discontinuity (MLD). However, simple lithospheric delamination alone cannot explain the extensive volcanic activity and significant tectonic deformation observed within cratons. Many cratons experience lithospheric thinning without undergoing full destruction. Therefore, the modification of the mantle lithosphere above the MLD following lithospheric thinning may be crucial to understanding craton destruction. This study focuses on the North China Craton, of which at least the eastern part has been destroyed since the Mesozoic, using anisotropic characteristics to constrain the modification of the residual mantle lithosphere (above the MLD). Our results show that the entire mantle lithosphere in the craton destruction zone exhibits a consistent fast-wave polarization direction, likely a result of a thorough modification during craton destruction. This intense modification may have rendered the originally shallow mantle lithosphere unable to resist further tectonic deformation after losing its deeper counterpart in the early Cretaceous, and thus could have easily reoriented the anisotropic minerals in response to the regional lithospheric extension. Such a process might have led to the formation of large amounts of both mantle- and crust-derived magma, giving rise to the coeval intensive magmatism of multiple sources in the North China Craton.