Segmented up-bending of the Arabian continental plate revealed by Pn attenuation tomography

Abstract

The Zagros orogen in the Iranian Plateau is a natural laboratory in which to investigate the tectonic evolution of the transition from oceanic subduction to continental collision. However, where slab detachment occurred and how slab detachment affects shallower continental subduction remain poorly understood. The formation mechanism of the post-collision magmatism is also unclear. Here, we construct a high-resolution Pn-wave attenuation model for the uppermost mantle beneath the Iranian Plateau and surrounding areas using a newly compiled dataset. Weak Pn attenuation delineates the Arabian Plate front near the Moho discontinuity, extending further toward the subduction direction in the northwestern and southeastern parts, possibly due to the up-bending and underplating of the Arabian lithosphere after the loss of slab pull. The correlations among the surface Miocene-Quaternary volcanism and strong Pn attenuation in the uppermost mantle suggest that asthenospheric materials escaped from slab windows and further feed the post-collision volcanoes.