We integrate previous work on the Hegenshan–Heihe suture with our interpretation of geomagnetic anomaly and seismic reflection data to investigate the role of the Hegenshan–Heihe suture in the evolution of late Mesozoic extensional structures in the Wunite depression of the Erlian Basin. Sags in the Wunite depression present as NE50° trending in the western sector, N0°–NE30° trending in the central sector and NE45° trending in the eastern sector. Our results highlight the importance of the pre-existing Hegenshan–Heihe suture in the evolution of the late Mesozoic rift system and reveal the following details. (1) The NE50° extent sags in the western sector are controlled by the c. NE50°-trending suture. Moreover, the extensional deformation of the reactivated suture during Early Cretaceous time resulted in a further vertical and horizontal extension of major border faults. (2) The N0°–NE30° extent sags in the central sector are influenced by the c. NE75°-trending suture. The sinistral strike-slip component of the reactivated suture during Early Cretaceous time resulted in a strike rotation of major border faults from NEE-trending (following the suture) to NNE-trending. (3) Because of strike-slip deformation, which resulted from the deformation of the reactivated suture accrued in major border faults, light dip-slip deformation led to less vertical offset. (4) The NE45°-trending sags in the eastern sector are controlled by the c. NE45°-trending suture. Moreover, the extensional deformation of the reactivated suture during Early Cretaceous time facilitated a further vertical and horizontal prolongation of major border faults.

We investigate the formation and deformation of transfer zones and their impact on sedimentation during multiphase rifting using a three-dimensional seismic dataset in the Baxian Sag, the onshore part of the Bohai Bay Basin, northern China. The fault system in the study area is dominated by two arcuate, opposing boundary faults, that is, the Niudong and Maxi faults, which form an S-type fault system which does not link together. The fault system and structural-stratigraphic features between the Eocene and Oligocene syn-rift sequences were distinctly different during the Palaeogene rifting. These differences allow us to identify the two-phase transfer zones: (1) a NW–SE-trending Eocene transfer zone linking the NW-tilted Baxian Block and the SE-tilted Raoyang Block , and (2) the N–S-trending Oligocene transfer zone forming along the central part of the S-type fault system between the two inward kinks, and linking S-tilted and N-tilted fault blocks. The two-phase transfer zones comprise transverse boundary fault segments and fault styles which are related to strike-slip motion. The strike-slip faults occurred in the sequence where the transfer zone formed. The transfer zones significantly influenced the syn-rift sediments, drainage catchments and reservoir properties during the periods when they formed, and the two-phase transfer zones represent favourable positions for hydrocarbon accumulation in the Eocene and Oligocene sequences, respectively.