Mesozoic-Cenozoic tectonic evolution of the western Bozhong Depression and controls on uplift-and-depression framework

The uplift-and-depression pattern of the Bozhong Depression represents a shallow tectonic response to the multiple-sphere interactions and plays a critical controlling role in sedimentary filling, tectonic evolution, and hydrocarbon accumulation in the Bohai Bay Basin, East China. However, its Mesozoic-Cenozoic tectonic evolution and formation mechanism remain unclear. Integrating drill core data and high-resolution 3D seismic data, this study systematically analyzes the structural framework and evolutionary history of the western Bozhong Depression. Seven regional unconformities are identified, dividing the strata into eight tectono-stratigraphic units. Balanced cross-section restoration delineates eight evolutionary stages from the Late Triassic compression to the Neogene thermal subsidence. The Late Triassic compression produced a maximum shortening of ca. 6.14 km, while the Early Cretaceous extension yielded a stretching of ca. 17.66 km. These results indicate that the Paleogene normal faulting, driven by reactivation of pre-existing faults and development of new faults, controlled the present uplift-and-depression pattern with differential evolution of the Chengbei, Shaleitian and Shijiutuo uplifts. The Chengbei uplift originated from Cenozoic overall northeastward tilting, the Shaleitian uplift represents a long-term inherited paleo-uplift, and the Shijiutuo uplift exhibits gradual west-to-east uplift. By linking Mesozoic fault reactivation directly to Cenozoic structural patterns, this study demonstrates that the structural preform inherited from earlier compressional epochs dictates the kinematics of subsequent extensional phases. Furthermore, these findings establish a new tectonic model and geodynamic framework applicable to similar intracratonic basins worldwide that exhibit pronounced tectono-sedimentary differentiation, shifting basin analysis from homogeneous extension models to those incorporate structural inheritance. Thus, understanding the formation mechanism of the uplift-and-depression framework is crucial for elucidating basin evolution and predicting hydrocarbon distribution.