Seismic geomorphology has provided effective technical support for the study on the sediment dispersal system in poorly drilled area based on seismic data. In this paper, taking the Neogene strata of eastern Liaodong region in the Bohai Bay Basin, eastern China, as an example, strata slicing was performed in the 3D seismic data volume with phase adjustment under the constraints of a few drilling and logging data, which aims to depict the planar distribution and evolution of the sandbodies of Guantao–Minghuazhen Formation layer by layer. One hundred and seventy-five isochronous strata slices of amplitude attribute were extracted in the time domain, which had greatly improved the quality of sandbody planar distribution map and provided an effective method for analyzing the sedimentary microfacies of different periods and their evolution in the study area.

The Shahejie Formation in Nanpu Sag is a crucial region for deep-layer hydrocarbon exploration in the Bohai Bay Basin. To address the impact of faults on sublacustrine fan formation and spatial distribution within the study area, this study integrated well logging, laboratory analysis, and 3D seismic data to systematically analyze sedimentary characteristics of sandbodies from the first member of the Shahejie Formation (Es₁) sublacustrine fans, clarifying their planar and cross-sectional distributions. Further research indicates that Gaoliu Fault activity during Es₁ deposition played a significant role in fan development through two mechanisms: (1) vertical displacement between hanging wall and footwall reshaped local paleogeomorphology; (2) tectonic stresses generated by fault movement affected slope stability, triggering gravitational mass transport processes that remobilized fan delta sediments into the central depression zone as sublacustrine fans through slumping and collapse mechanisms. Core observations reveal soft-sediment deformation features, including slump structures, flame structures, and shale rip-up clasts. Seismic profiles show lens-shaped geometries with thick centers thinning laterally, exhibiting lateral pinch-out terminations. Inverse fault-step architectures formed by underlying faults control sandbody distribution patterns, restricting primary deposition locations for sublacustrine fan development. The study demonstrates that sublacustrine fans in the study area are formed by gravity flow processes. A new model was established, illustrating the combined control of the Gaoliu Fault and reverse stepover faults on fan development. These findings provide valuable insights for gravity flow exploration and reservoir prediction in the Nanpu Sag, offering important implications for hydrocarbon exploration in similar lacustrine rift basins.