Braided‐Delta Migration Reflects Lake‐Level and Climate Controls (Permian Shihezi Formation, Ordos Basin, China)

ABSTRACT

Lacustrine sedimentary environments and sand‐body architectures are influenced by lake‐level fluctuations and climate, but understanding their relative contributions in deeply buried successions remains challenging due to the overprinting of diagenetic and tectonic processes. The Permian Shihezi Formation in the southwestern Ordos Basin provides an ideal setting for investigating how lake‐level variability influenced shallow‐water braided delta migration and reorganisation. Recent hydrocarbon exploration has yielded high‐quality cores and well logs, enabling detailed reconstructions of depositional processes. Using these datasets, we reconstruct the sedimentary characteristics, facies architecture and controlling processes of the Permian Shihezi Formation, developing an updated depositional model for its braided‐delta system. A revised sequence‐stratigraphic framework was established from integrated core‐log interpretation, aiding facies and systems‐tract identification. Facies analysis reveals that the braided‐delta system developed on a gently inclined basin margin with strong but variable hydrodynamics, frequent lake‐level shifts and significant long‐distance sediment transport. These characteristics make the Shihezi Formation a valuable analogue for shallow‐water continental systems preserved in other deeply buried basins worldwide. Stratigraphic patterns indicate a transition from early deposition characterised by climate‐related lake‐level variability broadly coincident with global eustatic cycles to later deposition increasingly controlled by regional tectonics, aridification and variations in sediment supply. Early‐stage sedimentation shows a broad temporal correspondence with higher‐order global highstand–lowstand cycles, while later stages record autogenic feedbacks through delta progradation, channel mobility and shoreline stabilisation. These trends suggest that the broad temporal correspondence between global eustatic cycles and regional lake‐level variability may reflect a common climatic background, whereas regional tectono‐climatic controls increasingly shaped later lake‐level and lacustrine‐system evolution.