The Paleozoic tectonic evolution of the northern margin of Gondwana is inferred to comprise several episodes of continental breakup and ocean opening. However, the timing and number of rifting events, and the identity and paleogeography of the continental blocks involved in these inferred breakup events remain poorly understood. This study examines the early Paleozoic tectonic evolution of northern Gondwana by analyzing the paleogeography and provenance of Ordovician strata exposed in the Iranian blocks. New detrital zircon U–Pb–Hf measurements from Ordovician siliciclastic strata in Iran define two major age fractions at 600—500 Ma (41 %; ɛHf_(t) =  −11.9 to +9.6) and 1100—600 Ma (37 %; ɛHf_(t) =  −21.6 to +10.6), and two minor fractions at > 1100 Ma (13 %; ɛHf_(t) =  −13.9 to +5.9) and 500—444 Ma (10 %; ɛHf_(t) =  −9.1 to +4.4). Detrital rutile U–Pb ages from these units similarly include two major age fractions at 1100—600 Ma (49 %) and 600—500 Ma (33 %), and two minor fractions at > 1100 Ma (14 %) and 500—444 Ma (4 %). Zr-in-rutile temperatures and Cr–Nb compositions indicate that most detrital rutiles are sourced from amphibolite facies metapelitic or metafelsic rocks. The new data suggest sediment was ultimately sourced from the Arabian-Nubian Shield (∼54 %) and 600—500 Ma (∼39 %) and Ordovician (∼7%) magmatic rocks in local basement in Iran. The widespread exposure of 600—500 Ma magmatic rocks in Iran indicates significant changes in basin configuration from a stable platform in the Ediacaran—Cambrian to a series of fault-bound extensional basins in the Ordovician. We explore two possible scenarios for the Ordovician extension in Iran. The first involves detachment of a continental block from northern Iran leading to opening of the Paleo-Tethys Ocean. However, because the identity of this hypothesized rifted continental block remains unclear, we interpret that early to middle Paleozoic extension across the region occurred within an already established continental margin.