Early Cretaceous compressive structures in the Nansha block (Dangerous Grounds): Implications for the late Mesozoic tectonic regime on the southern margin of the South China Sea

Abstract

The Mesozoic and Cenozoic tectonic evolution of South China is important for understanding the transition from subduction to extension related to the Paleo-Pacific plate. Here, the compressive structures of Lower Cretaceous sequences in the Liyue Bank (Reed Bank) and Nansha block (Dangerous Grounds) are presented using drilling data from Mesozoic strata and seismic data. Both south-directed and north-directed thrust nappes developed on the southern margin of the South China Sea. In addition, we observed a series of Early Cretaceous compressive structures in the Chaoshan Depression along the northern margin of the South China Sea. The compressive structures are accompanied by sedimentary environment changes from abyssal to continental deposition between 128.5 Ma and 79.5 Ma, which is perhaps associated with the collision between the South China block and Luconia block (Luconia-Dangerous Grounds-Reed Bank). The late Mesozoic thrust structures in the Chaoshan Depression and Liyue Bank (Reed Bank) and Nansha block (Dangerous Grounds) are related to the subduction of the Paleo-Pacific Ocean.