ICE 2022


Objectives For post-rift basins, fluvial sandstones are often the main reservoirs in fault blocks, nevertheless, identifying the distribution of rivers in fault blocks remains a challenge. Taking the Kendong Uplift in the Bohai Bay Basin as an example, based on the restoration of the river channel distribution from the Pliocene to the Holocene, combined with the analysis of paleo-topography and fault block tectonic evolution law, we clarified the reason for the counterclockwise migration of the river flow direction. Procedures Firstly, based on seismic attributes and coherence cube, we identified the distribution laws of faults and river channels in different time slices. When the fault throw is relatively large, a complete channel will be divided into different parts and appear in different time slices, otherwise, the channel can be fully displayed in a single time slice. We manually combine the divided parts of the channel in different time slices to restore the original appearance of the channel during the deposition period. Based on the position of the river channel in the hanging wall and footwall, we can identify the relative upstream and downstream of the river, and clarify the river flow direction. We restored the river flow direction in about 900 individual time slices from the Pliocene to the Holocene. Then, paleo-topography from Pliocene to Holocene was restored and fault block tectonic evolution law was established. Finally, the relationship between river flow direction, paleo-topography, and fault block rotation was clarified, which provides an excellent reference case for the study of the source-sink system. Results (1) The river flow direction has an obvious counterclockwise migration trend from the Pliocene to the Holocene in the Kendong Uplift. (2) The river flow direction is relatively consistent with the paleo-topography of the area, indicating that the topography is one controlling factor of river flow direction. (3) The change in paleo-topography is attributed to the localized rotation of fault block during late Pliocene to early Pleistocene. Therefore, we believe that the localized rotation of fault block is the main reason for the counterclockwise migration of river flow direction, as the localized rotation of fault block has changed the initial topography of the subsequent filling formations.