关键词: 平湖断裂带, 分段发育, 成因机制, 应力场旋转, 西湖凹陷, 东海盆地

Abstract: In order to reveal the formation and evolution process of Pinghu fault zone, to determine the segmentation characteristics of large-scale faults and their geological filling response, and to deepen the understanding of the complex fault development mechanism, this article  based on the latest 3D seismic data, conducts geometric and kinematic analysis of Pinghu fault zone. Combined with regional stress field analysis, the genesis and development mode of the faults are discussed. The research results indicate that: Pinghu fault zone is an “X”-shaped fault zone consisting of three segments and five main faults that alternate between NE and near NS. The NE fault segment formed earlier and has segmented development characteristics, while the NS fault segment formed later and controlled the segmented connections of the southern, central, and northern sections. The formation of complex faults in Pinghu fault zone is jointly controlled by two factors: The segmented growth and development of faults, and the rotation of regional stress fields during the Eocene. The growth and evolution process of Pinghu fault zone during the fault depression period is divided into three stages: Early NE fault segmentation development stage, middle NE-near NS fault hard connection stage, and late NS-NNE/NE fault tension torsion transformation stage. The temporal and spatial differences in the development and evolution of Pinghu fault zone play an important controlling role in the migration of local sedimentary subsidence centers and the differential development of compression reversal anticlines in the later stages of the fault.

Key words: Pinghu fault zone, segmented development, genetic mechanism, stress field rotation, Xihu sag, East China Sea basin