Timing of Arabia-Eurasia collision: Constraints from restoration of crustal-scale cross-sections

The timing of Arabia-Eurasia collision is crucial to the understanding of evolution of the Zagros orogen as well as the Himalaya-Tibet omgeny, but it remains an issue of considerable controversy. Drastically different estimates, ranging from 65 to 5 Ma, have been proposed for this issue. Although many workers prefer to consider that the Arabia-Eurasia collision initiated at 36-20 Ma, most of the tectonic responses to the collision occurred after 20 Ma. In this paper, we reconstruct the pre-collisional Arabian northeastern and Eurasian southwestern boundaries based on the restoration of ten crustal-scale cross-sections across the main body of the Arabia-Eurasia collision system, from which together with the positions of Arabia relative to Eurasia during the Cenozoic we infer the timing of Arabia-Eurasia collision. Our work shows that the Arabia-Eurasia collision started no earlier than similar to 18.3 +/- 1.2 Ma and that since the collision at least similar to 152 +/- 30-km-wide Arabian crust has underthrust Eurasia and Eurasian crust has been shortened for at least similar to 37 km. This may provide a reasonable explanation for why most of the tectonic responses to the collision occurred after 20 Ma.