Collision of North China and Yangtze Plates: Evidence from the South Yellow Sea

As an important geological event in East China, the collision of the Yangtze plate and North China plate gave rise to the formation of the Sulu-Dabie orogen. This paper made a thorough review on the different collision models. Data from seismic profiles and seismic tomography support the detachment model to the Lower Yangtze region. It says that the upper crust of the Yangtze Block detached from the lower crust, just like a crocodile opened its mouth, and the North China plate fortunately wedged into it. In the Qianliyan belt there developed similar gravity and magnetic anomalies with Sulu orogen, as the extension of the Dabie-Sulu orogen. In seismic profiles, the South Yellow Sea Basin and Qianliyan Uplift Belt are different in reflection characteristics. There are complete stratigraphic reflections in the basin but no obvious reflections in the uplift. All the boundaries show a south-dipping reflection patterns, suggesting the obduction of the Yangtze Block. The collision and derived compression mainly happened in Triassic while the growth strata deformation formed in lower Jurassic. In the lower crust of the Qianliyan Uplift, the Moho reflection is recognized at ～10 s, and disappeared below the South Yellow Sea Basin. It is thus speculated that the lower crust under the Qianliyan Uplift belong to the North China Plate, and the collision between Yangtze and North China caused the fading out of the Moho reflection. Generally, the geophysical data from the South Yellow Sea support the hypothesis that the North China Block wedged into the crocodile mouth of the Yangtze Block.