The Mesozoic tectonic evolution of the East China Sea Basin: New insights from 3D seismic reflection data

Abstract

The Mesozoic is a significant period in the East China Sea Basin (ECSB), since it recorded the tectonic transition from the Triassic Tethys tectonic domain to the subsequent Jurassic-Cretaceous Paleo-Pacific domain. However, the Mesozoic tectonic evolution of the East China Sea Basin is not well defined, and it has been highly debated in recent years. Here high-quality 3D seismic reflection data, information about fault timing, and fault maps were employed to analyze Mesozoic faulting and evolution of the ECSB. This study significantly improves our understanding of the Mesozoic tectonic evolution of the ECSB. Our results demonstrate that two sets of Mesozoic faults developed in the ECSB: (1) NW-striking faults are typical negative inversion structures and initially formed as low-angle thrusts as the result of multiphase plate convergence during Triassic. Then, the thrusts reactivated as extensional or transtensional faults during Cretaceous, which are interpreted to be related to NNW-SSE oblique extension associated with roll-back of the subduction zone of Paleo-Pacific plate. (2) The NE-striking faults are inferred to be thrust structures formed during the Early to Middle Jurassic. Flat-slab subduction of the Paleo-Pacific plate is introduced to explain the compression event during this stage. The NE-striking reactivated and newly-formed extensional faults were then developed extensively in the ECSB during the Cretaceous. The NNW-SSE oblique extension played a dominant role in this faulting event, which is related to roll-back of the subduction zone of Paleo-Pacific plate. Furthermore, the NE-striking faults continued to propagate cut through the Cenozoic sequence, since the strike of these faults is perpendicular to the Cenozoic extension stress field.