U–Pb dating of volcaniclastic deposits from the Sinj Basin: implications for provenance and the tectono-sedimentary evolution of the External Dinarides

Ar dating. Subsequent studies demonstrated that lacustrine flooding was diachronous. However, the influence of the Miocene Climatic Optimum (MCO) or the regional Miocene extensional tectonics is still debated. This study provides new constraints on the evolution of the Sinj Basin by integrating previous dating results with new LA-ICP-MS U-Pb-zircon dating of volcaniclastic and residual deposits from the NW, central, and SE parts of the basin. The obtained U-Pb ages range between ~ 17.7 and ~ 15.3 Ma and provide new constraints on the timing of initial lacustrine flooding. Correlation with the MCO suggests a close relationship between climate change and lacustrine development. Lake-level falls reflected by conglomerates and coals deposited in marginal and more distal parts of the basin, respectively, suggest environmental instability after ~ 15.3 Ma, towards the end of the MCO. Detrital zircon grains reveal a wide spectrum of ages from the Neoproterozoic to the Early Miocene, suggesting multiple redeposition cycles, starting with the Cadomian and Variscan orogenies, followed by Cretaceous-Oligocene uplift of the Dinarides, and the recycling of foreland basin deposits into the Miocene Sinj Basin. Finally, this study demonstrates the usefulness of LA-ICP-MS U-Pb dating for the reconstruction and correlation of isolated intramontane basins. Supplementary Information: The online version contains supplementary material available at 10.1007/s00531-026-02567-w.