Evolution of the Zagros sector of Neo-Tethys: Tectonic and magmatic events that shaped its rifting, seafloor spreading and subduction history

The evolution of the Neo-Tethys realm had a significant impact on the Phanerozoic paleogeography of the Iran Plateau. However, there remains significant debate regarding the timing of the opening and closure of the Neo-Tethys ocean, as well as the initial stages of subduction and the style of subduction. In this paper, we review the geological data relevant to the Zagros sector of the Neo-Tethys and the associated arc zones (SaSZ and UDMA) in order to update our understanding of the geodynamic history of this region, from early rifting to final closure. Our analysis of Late Devonian-Early Permian rift-related rocks and subsequent subsidence and shallow marine sedimentation through the Triassic period provides compelling evidence for the occurrence of rifting and the formation of a passive margin in the Late Paleozoic. The Late Triassic closure of the Paleo-Tethys ocean in northern Iran marks the inception of Neo-Tethys ocean subduction. Our revised perspective on the subduction style suggests that subduction of the Neo-Tethys oceanic slab began simultaneously across the entire zone in the Late Triassic-Early Jurassic, leading to the production of intraoceanic arc magmatic rocks. However, the variable rates of magma production and the change in the geochemical signature of magmatic rocks from oceanic to continental type observed in the northern domain during the Middle-Late Jurassic indicate a shift from intraoceanic arc to continental arc subduction. In the southern segment, intraoceanic subduction was still ongoing during this time period. While the early Cretaceous in the southern segment is characterized by the initial obduction of ophiolites, the Late Cretaceous in the entire zone is marked by the underthrusting of the Arabian passive margin, coinciding with the obduction of Cretaceous ophiolites on the overriding plate and the subsequent subduction of stretched and denser continental Arabian lithosphere with overlying ophiolites. Our tectonic reconstruction highlights the asynchronous nature of the final closure of the Neo-Tethys, which occurred first along the northern margin during the Late Eocene-Early Oligocene and then along the southern margin during the Miocene.