New investigations in the Neyriz region of Iran provide support for the hypothesis that Mesozoic radiolarite and ophiolite have been thrust southwestward as nappe complexes over the autochthonous Cretaceous carbonate platform deposits directly south of the Zagros Crush Zone. A Late Cretaceous wildflysch sequence is excluded from the nappe complex and put in the autochthonous unit. Different types of radiolarite are distinguished, and a variety of limestone olistoliths are recognized within these rocks. The structural and stratigraphic sequence in the Neyriz region closely resembles that of the Oman Mountains. A model is proposed in which a rifted and subsequently aseismic continental margin of Arabia persisted through much of the Mesozoic Era. In Late Cretaceous time the pattern of plate motion changed, and Arabia was driven toward central Iran, with the consequent progressive destruction of the intervening ocean and emplacement of nappes from the northeast.