Events contributing to the destruction of the North China craton
The NC and SC initially collided in the Early Mesozoic and collision probably lasted to Middle Jurassic time (Yin and Nie, 1993; Zhang, 1997). The NC experienced intra-plate deformation during which folds with east-west trending axes formed (Wang et al., 2005). This intra-plate deformation was responsible for the construction of the North China Plateau (Zhang et al., 2001a, 2001b, 2001c; Shao et al., 2003). In the Late Mesozoic, the Kula plate was quickly moving north-northwest and was subducting beneath the Eurasian continent (Hilde et al., 1977). Subduction led to mantle upwelling and widespread magmatic activity in eastern China (including the eastern NC). The lithosphere of the Eastern North China Plateau had been thinned by intense extension and several Late Mesozoic rifts developed in the Eastern North China Plateau under a transtensional stress field also responsible for the northwest trending en echelon arrangement of grabens on the west of the Tanlu Fault Zone (Figure 7a). The Mesozoic rifting ended in the Late Cretaceous and was followed by temporary uplift and erosion.
The Pacific plate moved northward and subducted beneath the Eurasian plate since 53 Ma at the average rate of about 25 mm/yr (Parés and Moore, 2005). This led to a sinistral strike-slip reactivation of the Tanlu Fault Zone. The northwest-trending, en echelon-arranged narrow grabens that developed in the extensional stress field were Paleocene to Early Eocene in age and were filled by the pre-rift sediments. At the same time, the Japanese arc belonged to the part of the northeast Asian marginal zone, the Okhotsk-Chukotka volcanic zone, which also experienced sinistral strike-slip movement within the northeast trending Sikhote-Alin Fault Zone (Lallemand and Jolivet, 1986; Jolivet et al., 1988, 1994; Liu et al., 2001).
The Pacific plate has moved in a west-northwest direction instead of a northward direction since 42 Ma at an average rate of 32 mm/yr (Parés and Moore, 2005). This has led to dextral strike-slip motion instead of the former sinistral strike-slip motion within the Tanlu Fault Zone. The change in motion triggered upper mantle upwelling and intense volcanic activity as the Bohai Bay Basin entered a new stage in its tectonic development. A late Eocene and Oligocene transtensional basin was created in the offshore portion of the Bohai Bay Basin (Figure 7b) while the Japanese arc began to separate from the northeast Asian margin (Lallemand and Jolivet, 1986; Jolivet et al., 1994) and northeast Asia, as a whole, experienced lithospheric thinning.
The late Oligocene (32-25 Ma) was the first stage of the Japan Sea opening. During this period, the Japan Sea was a pull-apart basin between two dextral strike-slip faults and transition from continental to oceanic rifting occurred (Jolivet et al., 1994). The regional compressive stress was northeast-southwest in northeast Asia and the Tanlu Fault Zone was reactivated within the new stress field. The Bohai Bay Basin developed intense volcanics and wider transtensional basin under the same stress regime as the Japan Sea (Figure 7c) and, in this period, the Korean peninsula moved anticlockwise, breaking away from the Chinese mainland (Qian, 2004). The motion of the Pacific plate coupled with the coeval Indian-Eurasian collision intensified extension in northeast Asia and the Bohai Bay Basin experienced a second stage of extension in response to opening of the Japan Sea.
In the Miocene (25-12 Ma), the Japan Sea continued to open and was transformed from pull-apart basin to back-arc spreading centre, triggering the onset of oceanic crust formation. The spreading ridge in the Japan Sea ran approximately north-south (Jolivet et al., 1994; Itoh, 2001). The principal compressive stress was approximate E-W in the Northeast Asia due to the interaction between the Indian, Eurasian and Pacific plates and the southwest of Japan developed inversion structures in this period (Itoh, 2001). The Bohai Bay Basin stopped rifting in this compressive stress field and the basin, as a whole, experienced thermal subsidence. The Tanlu Fault Zone became a transpressive dextral strike-slip zone (Xu, 1993) while the Bohai Bay Basin experienced inversion deformation (Figure 7d) (Zhao and Zheng, 2005; Zhao and Windley, 1990).
Northeast Asia was still in the E-W trending compressive regime in the Pliocene (12-2 Ma). The Japan Sea stopped opening, and rifting within the Bohai Bay Basin was reduced as the region entered a post-rift stage and experienced thermal subsidence. From 2 Ma, the compressive stress changed to a northeast-southwest orientation in northeast Asia (Huang et al., 1996) and tectonic subsidence was superimposed on the offshore portion of the basin (Hu et al., 2001) (Table1).
The intensity of Cenozoic extension in the Bohai Bay Basin suggests that the destruction of the NC occurred mainly in the east of the craton during the Cenozoic. The destruction of the craton was concentrated in the offshore portion of the Bohai Bay Basin.