<p>The Shangdan suture zone preserves critical information about the Paleozoic collision between the North and South Qinling Belts. Although this collision event significantly influenced the tectonic evolution of the Qinling Orogenic Belt, the timing remains a subject of debate. In this study, we comprehensively analyzed the Th/U ratios, elongation ratios, and U–Pb ages of detrital zircons to investigate provenance signatures and tectonic-sedimentary settings. Detailed U–Pb dating of detrital zircons from Ordovician to Devonian strata in the Shanyang and Xunyang area of South Qinling Belt revealed age clusters of 430–450, 710–840, and 910–960 Ma for Devonian and Silurian samples, with peaks at ~ 440, ~ 800, and ~ 940 Ma, respectively. Ordovician samples predominantly exhibited ages of 710–850 Ma, peaking at ~ 735 Ma, but lacked the 910–960Ma age group. Comparison with magmatic events in adjacent terranes and detrital zircon mixing provenance modeling identified 430–450 and 910–960 Ma peaks associated with granitoids in the North Qinling Belt, while the 710–840 Ma age population corresponded to sources from the South China Block and South Qinling Belt. Provenance analysis indicated that Devonian and Silurian samples originated from the northern and southern sides of the Shangdan suture zone, whereas Ordovician samples were derived from the southern side. This shift in provenance suggests a significant change in sedimentary sources in the South Qinling Belt from the Ordovician to the Silurian. The closure of the Shangdan Ocean likely occurred during the Silurian-Devonian period, resulting in a northern provenance for the Silurian and Devonian strata.</p>