Destruction mechanism of the North China Craton: Insight from P and S wave mantle tomography

The eastern part of the North China Craton (NCC) was reactivated and its lithosphere was destructed during the Mesozoic to Cenozoic. Several destruction models have been proposed by geochemical and geologic studies. In this work we determined detailed P and S wave velocity and Poisson's ratio structures under the NCC, which show different structural patterns in different blocks of the NCC. The present results provide important new constrains on the NCC evolution mechanism. Integrating geochemical and geologic observations and our tomographic results, we consider that deep subduction of the Pacific slab under East Asia caused local or regional scale lithospheric delamination that first took place along some special locations such as the Trans-North China Orogen, Dabie-Sulu and Yanshan orogenic belts in early Mesozoic or Paleoproterozoic. As a result, asthenospheric upwelling in the big mantle wedge above the stagnant Pacific slab led to widespread magmatism in and around the eastern part of the NCC. Hence the thermal erosion and/or chemical metasomatism might be a main dynamic mechanism for the lithospheric evolution of eastern NCC during the Mesozoic to Cenozoic. We suggest that the Tanlu Fault Zone and Trans-North China Orogen may have acted as two main conduits for the asthenospheric upwelling, which have played an important role in the Mesozoic-Cenozoic destruction of the pre-existing Archean lithospheric mantle. (C) 2011 Elsevier Ltd. All rights reserved.