克拉通岩石圈减薄与破坏

Abstract

It has been proposed that the North China Craton (NCC) was thinned up to a thickness of >100 km during the Phanerozoic, and underwent an associated craton destruction. Evidently, it is an important topic worthy of future study to understanding the mechanism of cratonic destruction and its role played in the continental evolution. After synthesized the global cratons of India, Brazil, South Africa, Siberia, East Europe (Baltic) and North America, we found that lithospheric thinning is common in the cratonic evolution, but it is not always associated with craton destruction. Most cratons was thinned by thermal erosion of mantle plume or mantle upwelling, which, however, may not cause craton destruction. Based on the studies of the North American and North China Cratons, we suggest that oceanic subduction plays an important role in caton destruction. Fluids or melts released by dehydration of the subducted slabs metasomatize the mantle wedge above and trigger extensive partial melting. More importantly, the metasomatized mantle lost its original rigidity and make craton easier to be deformed and then to be destoyed. Therefore, we suggest that the widespread crust-derived granite and large-scale ductile deformation within the continental crust can be regarded as the petrological and structural indicators of craton destruction, respectively.