New Cambrian paleomagnetic constraints on South China Block paleogeography and Gondwana linkages

The Early Paleozoic paleogeographic position of the South China Block (SCB) and its affinity with Gondwana remain contentious. This study presents new, high-quality paleomagnetic data from Cambrian Stage 3 clastic rocks (Kunming, southwestern SCB) that quantitatively constrain its early Paleozoic paleogeography.Systematic analyses identify a primary remanent magnetization carried by detrital magnetite. This component passes fold and reversal tests, shows no significant inclination shallowing, and averages out secular variation. Following a regional Cenozoic rotation correction, the paleopole positions the SCB at a paleolatitude of ~13.6°S at ~518 Ma. This location places its outhwestern margin adjacent to the western margin of East Gondwana. Paleogeographic reconstructions illustrate a contiguous spatial relationship and a concordant margin orientation between the two blocks. Our new paleomagnetic pole, supported by existing paleobiogeographic and provenance data, firmly establishes the SCB as a constituent part of East Gondwana from the Early Cambrian to Early Devonian (~520–405 Ma). These results provide robust evidence for refining Cambrian paleogeographic models of Gondwanan assembly.