Deep-shallow coupling response of the Cenozoic Bohai Bay Basin to plate interactions around the Eurasian Plate

Abstract

The Bohai Bay Basin (BBB) is a Meso–Cenozoic intracontinental petroliferous basin, where four pre-existing continental-scale fault zones intersect, in East China. The BBB has experienced complex deformational and evolutionary history that records significant information about how the lithosphere there has responded to the coeval plate interactions around the Eurasian Plate and/or their resulting deep crust-mantle processes in the Cenozoic. Now both deep and shallow deformational and evolutionary processes of the BBB have been well-studied, but many geodynamic mechanisms previously proposed for those processes are too general to explain them well. Based on various data and principles, we first summarized both deep and shallow responses and processes of the BBB in the Cenozoic and then matched reasonable geodynamic mechanisms for each of them. The results show as follows: the Cenozoic differential reactivation of pre-existing continental-scale weak zones controlled the coeval deep-shallow differential coupling evolution of the BBB. The Paleogene extension in the BBB was mainly caused by crust-mantle processes triggered by the stagnant Izanagi slab. The Cenozoic strike-slip faulting was influenced by various plate interactions, in which the oblique subduction and anticlockwise rotation of young Pacific Plate resulted in the complex pre-Oligocene strike-slip history of the Tan–Lu Fault Zone to the south of the Zhang–Peng Fault Zone, while the India-Eurasia collision has caused the intense and synchronous strike-slip faulting of various faults there since ~35 Ma, which was then weakened by the oblique subduction and clockwise rotation of young Philippine Sea Plate in the Neogene. The compression resulting from both the India-Eurasia collision and the Philippine Sea Plate's subduction contributed to the latest Paleogene tectonic inversion in the BBB. The arrival of mantle flow triggered by both the India-Eurasia collision and the stagnant slab of the Pacific Plate resulted in the tectonic reactivation there in the late Neogene.