The Transition From Weak Extension to Weak Compression in Cratonic Basin: Constraints From Sediment Flux

Sediment flux analysis offers critical insights into the spatial and temporal distribution of clastic materials in sedimentary basins, enabling the reconstruction of tectonic features and source‐to‐sink processes. This study focuses on the Lower Cambrian Qiongzhusi Formation, a key hydrocarbon source rock and shale gas reservoir in the Sichuan Basin, western Yangtze Block. By integrating lithology, thickness, and density data from drillings and outcrops into a 3D ArcGIS model, we analysed sediment flux to resolve debates about the basin's tectonic history. Results reveal distinct spatial distributions between the upper and lower segments of the Qiongzhusi Formation: (1) The spatial distribution of clastic materials in the lower segment of the Qiongzhusi Formation was primarily controlled by the geomorphic constraints of the extensional trough, (2) The sedimentary center of the upper Qiongzhusi Formation shifted northwestward, exhibiting a distinct northwest‐thickening and southeast‐thinning trend. This spatial reorganisation reflects a fundamental change in basin dynamics: the lower segment's sedimentation was controlled by the geomorphic constraints of a weakly extensional trough, while the upper segment's asymmetric thickness and elevated sediment flux along the northwestern margin (linked to crustal shortening) signal the onset of weak compression. Collectively, these observations indicate a tectonic transition from a weakly extensional trough to a weakly compressive foreland basin, driven by regional compressional forces during the Early Cambrian. This study provides new constraints on the dynamic evolution of the Sichuan Basin.