In the light of plate tectonic theory, a model for the evolution of the Zagros mountain system in southern Iran is proposed. A suture zone, which lies between the Arabian and Persian plates, comprises the Zagros mountain range. The suture zone is divisible into five segments, each of which reflects the various lithologic and tectonic environments associated with stages in the collision of the Arabian and Persian continental masses.
A trench resulting from the subduction of the Arabian plate beneath the stable block of the Persian plate persisted until late mid-Cretaceous time. This was the site of radiolarian chert deposition and associated turbidites and olistoliths. Sharp facies changes in Upper Cretaceous sediments immediately southwest of the trench and severe tectonism in the crush zone to the north of the trench are suggestive of movements which involved the rupture and upward thrusting of slices of oceanic crust now manifest as a belt of ultramafic rocks in the trench zone. Subsequent northward movement of the Arabian plate during Tertiary time resulted in thrust faulting and overfolding in the imbricated belt adjoining the trench zone and more gentle folding in the simply folded belt to the southwest.