Characteristics and formation mechanisms of Mesozoic compressional structures in the Huanghua Depression, Bohai Bay Basin, China

Abstract

Abstract The Huanghua Depression is a complex secondary tectonic unit in the Bohai Bay Basin of eastern China. This work analyses the geometric features and formation mechanisms of Mesozoic compressional structures developed within the Huanghua Depression. Compressional deformation has formed open-fold, single reverse or thrust faulting, duplex structures and imbricated structures that can be divided into two dominating groups by their distribution direction: nearly E–W- and WNW-directed and NNE- and NE-directed. There are three phases of Mesozoic compression: Late Triassic, Late Jurassic–earliest Early Cretaceous and Late Cretaceous. The Late Triassic compressional structures were formed by near N–S- and NNE-directed compressional stress whereas late Jurassic–earliest Early Cretaceous and Late Cretaceous compressional structures were formed by a WNW-directed compressional stress field. The three phases of Mesozoic compression in the Huanghua Depression are consistent with the evolution of the regional tectonic setting, in particular the interaction mode and timing of the North China Block with surrounding plates. KEY POINTS Compressional deformation in the Huanghua Depression can be divided into two dominating groups by their distribution direction: nearly E–W- and WNW-directed and NNE- and NE-directed. There are three phases of Mesozoic compression: Late Triassic, Late Jurassic–earliest Early Cretaceous and Late Cretaceous. The three phases of Mesozoic compressional structures in the Huanghua Depression are consistent with the evolution of the regional tectonic setting.