Cenozoic faulting of the Bohai Bay Basin and its bearing on the destruction of the eastern North China Craton

Abstract

The Cenozoic Bohai Bay Basin is located at the center of the Eastern Block of the North China Craton. The structural architecture of this basin provides important clues on the deep-seated lithosphere thinning of the North China Craton. The Cenozoic regional stress field is characterized by NW-oriented extension. However, the various Cenozoic structural patterns of normal faulting and related transverse folding in the Bohai Bay Basin are controlled not only by Cenozoic stress field, but also by strain field and Mesozoic basement fault assemblages in this area. Regionally, the Cenozoic tectonic features and the dynamic evolution of the eastern North China Craton are dominated by two lithosphere-penetrating fault systems including the sinistral Tan–Lu Fault System and the dextral Lan–Liao Fault System. To the west of the Lan–Liao Fault System, Cenozoic extensional tectonics includes NNE-trending listric normal faults that controlled half grabens. However, between these two fault systems are WNW-trending half grabens which show basement-involved faulting in the north and overlapping relations between sedimentary cover and basement in the south. To the east of the Tan–Lu fault, the North Yellow Sea Basin is a WNW-trending fault depression with faulting in the south and overlapping relations in the north. These structural features are inherited from the Mesozoic tectonic framework of this area, whose tectonic characteristics were completely controlled by two opposite strike-slipping faults, the trans-extensional or oblique rifting in the Paleogene, followed by extensional faulting and subsequent subsidence. Furthermore, the culmination of the decratonization of the North China Craton was also related to an eastward jump of Cenozoic subduction of the Pacific Plate and the far-field effect of eastward extrusion of Cenozoic subduction of the Indian Plate, and was not essentially restricted to the early Mesozoic processes. Therefore, the Cenozoic, especially ∼25Ma marks the time of cessation of the processes that led to lithosphere thinning and destruction of the Eastern Block of the North China Craton.