Dual provenance signature of Upper Devonian sandstones along the northern Gondwanan margin: zircon U–Pb–Hf evidence from the Ilanqareh Formation, NW Iran

Late Devonian siliciclastic strata in northwestern Iran record sedimentation along the northern Gondwanan margin bordering the Paleo-Tethys Ocean. However, their provenance and tectonic significance remain poorly constrained, limiting paleotectonic reconstructions. To address this uncertainty, four representative sandstone samples from the Upper Devonian Ilanqareh Formation were analyzed petrographically and through detrital zircon U–Pb–Hf geochronology. The Ilanqareh sandstones are quartz-arenitic and compositionally mature, consistent with recycled continental detritus. Detrital zircon ages are multimodal, with Neoproterozoic–Cambrian peaks at ~590–560, ~630–610, ~810–780, and ~970–920 Ma. Minor Late Devonian to earliest Carboniferous zircons (~380–323 Ma) are present, along with sparse Paleoproterozoic to Archean zircons at ~2.55–1.9 and ~3.1–2.9 Ga. Corresponding εHf(t) values indicate variable contributions from juvenile magmatic sources and reworked continental crust. The youngest concordant zircon age (374 ± 12 Ma, 2σ) provides a Late Devonian maximum depositional age consistent with biostratigraphic constraints. Comparison with regional detrital zircon records from the Zagros and Alborz basins highlights a shared Pan-African–Neoproterozoic inheritance across Iran, but the Ilanqareh Formation preserves a broader εHf(t) spread and rare syn-depositional Devonian grains, consistent with a transitional position between dominantly recycled Gondwanan detritus and limited contemporaneous magmatic input along the northern Gondwanan margin.