Cenozoic Evolution of the Rongcheng High from High-Resolution 3D Seismic Reflection Imaging

Abstract The Rongcheng High, located on the center of the Jizhong Depression, North China, presents favorable geothermal and geological characteristics, thereby rendering the fine subsurface structure crucial for accurately assessing seismic hazards and the potential for geothermal resources. In 2019, a recently acquired three-dimensional (3D) seismic dataset and processing methodologies were introduced to generate a high-resolution seismic reflection volume, centered on the Rongcheng High. The 3D reflection data revealed numerous prominent reflectors and associated fault structures, enabling a detailed study of the subsurface structure and providing an insight into the structural evolution of the Cenozoic Rongcheng High. A dissection of the fault system in the Rongcheng High unveiled a complex geometry characterized by both shallow and deep faults, indicating an initial phase of extension, followed by subsequent dextral strike-slip displacement. The Rongcheng Fault delineates the boundary between the Rongcheng High and Xushui Sag, influencing the fault sag and facilitating the development of a larger accommodation space. The depositional center shifted from west to east. The faults in the Cenozoic exhibited varying patterns of activity, beginning frequently in early Paleogene, followed by a decline, ultimately culminating in Neogene. The study area experienced two uplift events at the end of Ek2 (Kongdian-2 Formation) and Ed (Dongying Formation), resulting in the complete denudation of the Sha-2 and Dongying formations. A structural pattern characterized by alternating high and sag areas in the study area was established at the end of the depositional period of the Dongying Formation.