The Yangtze Block was a crucial component of the Gondwana supercontinent. During the Ediacaran–Early Cambrian, its western margin underwent a marked transition from carbonate- to siliciclastic-dominated depositional environments. However, the tectonic dynamics and geotectonic setting governing this pronounced sedimentary facies shift remain poorly constrained. Thick Lower Cambrian terrigenous clastic rocks widely exposed along the western margin of the Yangtze Block (Western Yangtze) serve as a key archive for tracing sediment provenance and deciphering Early Cambrian geotectonic evolution.

This study presents systematic detrital zircon U–Pb geochronological and whole-rock major- and trace-element geochemical analyses of the Lower Cambrian Qiongzhusi Formation in the Western Yangtze to constrain its provenance and tectonic background.

Whole-rock geochemical data indicate that high-field-strength elements (HFSEs) and large-ion lithophile elements (LILEs; e.g., Th, Zr, Hf, Ba, Pb) in the Qiongzhusi Formation clastic rocks align closely with upper continental crust (UCC) values. Conversely, elements such as Co, Ni, Y, Nb, Cs, Hf, and Ta are depleted relative to UCC, with Co, Cs, and Ta showing the most significant depletion. Characteristics of immobile elements (Th, Sc, Hf, Zr, Ho) and rare earth elements (REEs; e.g., La, Ce, Yb) consistently indicate a predominantly felsic igneous source. Detrital zircon U–Pb age spectra exhibit two primary population peaks at ca. 590–500 Ma and ca. 880–720 Ma, alongside two subordinate clusters at ca. 1900–1500 Ma and ca. 2500–2400 Ma.

Integrated with regional geological evidence, we propose that the Early Cambrian detritus was primarily derived from Ediacaran–Early Cambrian magmatic rocks within the Longmenshan tectonic belt, as well as weathering products of late Neoproterozoic felsic magmatic rocks from the Panxi–Hannan and Ailaoshan magmatic arcs. Subduction of the Proto-Tethys Ocean beneath the Western Yangtze during the latest Ediacaran–Early Cambrian established a Late Ediacaran–Early Cambrian magmatic arc. This tectonic event converted the Western Yangtze from a passive margin into an active continental margin, supplying voluminous Early Cambrian detritus that drove the major depositional transition from carbonates to siliciclastics. [Significance]These findings establish key provenance links between the Western Yangtze and surrounding orogenic belts, providing critical constraints for reconstructing the tectonic and paleogeographic evolution of the South China Block during the Ediacaran–Early Cambrian transition.