Evolution of Early Cretaceous extensional basins in the eastern North China craton and its destruction of the craton

Regional uplift occurred at the initial stage of destruction in the Late Jurassic eastern North China craton and Upper Jurassic deposits are absent in the whole area. In the early part of the Early Cretaceous, regional extension occurred and downfaulted basins formed, with the northern and southern margins of the craton showing more intense extension. The Yanshan structural belt on the northern margin is characterized by formation of metamorphic core complexes while the southern margin was occupied by wide rift-type basins. Volcanic eruption and magmatic intrusion commonly took place in the area in the middle Early Cretaceous. Narrow rift-type basins occurred in the craton in the late Early Cretaceous, and downfaulting along the NNE-trending Tan-Lu fault zone was most intense. The evolution of these downfaulting basins demonstrates that after surface uplift the craton lithosphere was hot and soft in the initial stage of the destruction, leading to development of metamorphic core complexes and wide rift-type basins. The destruction intensity shows inhomogeneous distribution and might be controlled by pre-existing lithospheric mantle structures in the early stage. In the late Early Cretaceous, the temperatures of the lithosphere under the craton decreased and the destruction intensity became high after the middle Early Cretaceous magmatic activities, which is responsible for development of narrow rift-type basins along pre-existing fault zones. The basin evolution processes support the view that the Late Mesozoic lithospheric thinning of the eastern North China craton was mainly caused by the mechanism of gradual delamination.