Changes of tectonic regime of the East China Sea Shelf Basin since Mesozoic: Insights from the Tiantai slope belt, East China Sea

Abstract

Because of its unique tectonic location, the East China Sea shelf basin is an ideal laboratory for studying the transition of the East Asian continent from the Paleo-Tethys tectonic domain to the Pacific tectonic domain. The Tiantai slope belt within the East China Sea shelf basin contains geological information regarding the Mesozoic tectonic system transformation of the basin. Therefore, understanding the structural characteristics and evolution process of the Tiantai slope belt is extremely important. The structural characteristics of the Tiantai slope belt are clarified through the interpretation of seismic data, and its structural model is established. The transition of the East China Sea shelf basin from the Paleo-Tethys tectonic domain to the Pacific tectonic domain is determined. The NWW-trending faults formed in the Jurassic were detachment fault systems. The stress direction shifted during the Early Cretaceous, forming an NE-trending structural feature. The difference in extensional strength between the north and south sides of the Tiantai slope belt allows the NWW-trending basement faults to slip as accommodation faults, regulating deformation and inducing shallow arcuate faults in their hanging wall. The tectonic evolution of the Tiantai slope belt indicates that the East China Sea shelf basin completed the transition from the Paleo-Tethys Ocean tectonic domain to the Pacific tectonic domain in the Early Cretaceous, and the East China Sea shelf basin has entered the back-arc rifting stage of the Pacific tectonic domain after the Jurassic continental marginal depression.