THE LATE MESOZOIC THRUST FAULT BELT IN THE NORTHERN PART OF THE SOUTH CHINA SEA AND ITS TECTONIC TRANSITION

The tectonic evolution of the Paleo-South China Sea is of great significance to the study of tensile fractures on the continental margin and the origin of basins. Controversies about the process of the tectonic evolution of the South China Sea have appeared for a long time. In this article, based on the previous studies and comprehensive comparison, as well as seismic interpretation, the authors made a study on the reverse fault system and compression fold structures with special attention to the lateral distribution pattern of the paleo-thrust zone and its activities in the northern South China Sea. After determination of the tectonic stress background of the northern South China Sea in late Mesozoic, the authors identified a Mesozoic thrust zone. We made studies on its location, distribution, activity cut-off time of the thrust zone. Based on all the facts above, the authors reestablished a new model of evolution since late Mesozoic for the South China Sea. Before the late Mesozoic, the northern part of the South China Sea was predominated by a compressive stress and a collision orogenism. An island-arc type of active continental margin was then formed. From late Cretaceous to Eocene, the main stress of the basin was gradually transformed from compressive to tensional from west to east; After Oligocene, the study area is under a tensile stress.