Tethys-marginal sedimentary basins in western Iran

Abstract

Five sedimentary basins formed along the Iranian margin of the southern Tethys Ocean during its evolution. These basins record the opening and closing of the ocean basin and the collision of what is now Arabia and Iran. The late Paleozoic–Jurassic Isfahan basin opened by continental rifting that began in the Devonian, and contains an early (late Paleozoic–Triassic), passive-margin sequence and a later clastic-wedge phase. The Early Cretaceous Sanandaj basin is a forearc overlying the tectonized and subsided Isfahan basin. The latest Cretaceous–Paleocene Kermanshah basin is a remnant of the Tethys Ocean basin. It initially lay along tectonic strike from the lengthening Arabian-Iranian collision orogen to the southeast but was later incorporated into the orogenic foldbelt. The late Cenozoic Zagros basin is a suture (foreland) basin that formed on the Arabian plate as it attempted subduction beneath Iran. The Paleogene tectonic setting of the Kashan-Gavkhuni basin is in doubt, but, by mid-Tertiary time, it was a foreland basin that lay landward of the collisional foldbelt and was nearly surrounded by other orogenic highlands that formed during convergence of other plates within and marginal to Iran.