Tectonic evolution of the Zagros Orogen in the realm of the Neotethys between the Central Iran and Arabian Plates: An ophiolite perspective

Abstract

The Zagros Orogenic Belt includes the Fold and Thrust Belt, the High Zagros Belt, the Outer Zagros Ophiolitic Belt, the Sanandaj-Sirjan Metamorphic Belt, the Inner Zagros Ophiolitic Belt, and the Urumieh-Dokhtar Magmatic Belt. We divide the High Zagros evolutionary history into five stages: (1) triple junction formation, (2) continental lithosphere rifting, (3) generation, spreading, and maturation of the Neotethys Ocean, (4) subduction of the oceanic lithosphere, and (5) collision. The Neotethys triple junction, located at the southeastern corner of the Arabian Plate, formed during the Late Silurian-Early Carboniferous. Subsequently, this triple junction became a rift basin due to normal faulting and basalt eruption. The rifting stage occurred during the Late Carboniferous-Early Permian. Thereafter, extension of the basin continued, leading to spreading and maturation of the Neotethys oceanic basin during the Late Permian-Late Triassic. Probably at the end of the Late Triassic, closure of the Paleotethys Basin caused the initiation of two northeastward subductions: (1) oceanic-oceanic and (2) oceanic-continental. Oceanic-oceanic subduction continued until the Late Cretaceous and was terminated by the emplacement of the Outer Zagros Ophiolites, whereas oceanic-continental subduction continued until the Middle Miocene. Subduction in the southern Neotethys Basin between the Arabian and Central Iran Plates caused a tensional regime between Sanandaj-Sirjan and Central Iran, and the formation of a back-arc basin that by its closing led to the emplacement of the Inner Zagros Ophiolites during the Late Cretaceous.