A new 3D S-velocity model for the lithosphere-asthenosphere system of the Arabian Peninsula and the Iranian plateau

Abstract

For the first time, a 3D S-velocity model of the lithosphere-asthenosphere system (from 0 to 400 km-depth) has been achieved for the Arabian Peninsula and the Iranian plateau, through Rayleigh-wave analysis applied to the traces of 116 earthquakes, which have been registered by 209 seismic stations. The precise location and structure of the asthenosphere has been determined from this model, which has not been obtained in other previous studies. Other interesting geological and tectonics features has been revealed from this new model, e.g., an elongated low S-velocity anomaly in the upper mantle and shallow asthenosphere, determined from the Afar plume to the north of the Jordan plume, may be interpreted as a thermal upwelling and a horizontal flow from these mantle plumes. This combination of low S-velocity and shallow asthenosphere, jointly with the low S-velocity determined at 10–30 km-depth for this region, poses the question whether there is a lithospheric-to-crustal plumbing system for the magma, which could feed the Cenozoic volcanism observed in this area. The present S-velocity model shows that this hypothetic plumbing system could exist in this region. For the Makran region, the high S-velocity pattern associated to the Arabian slab fuses at ~ 150 km-depth with the high S-velocities determined below the asthenosphere. This feature can be interpreted as the slab disappears at this depth, fusing with the mantle, and may be the reason of no occurrence of earthquakes associated to this slab deeper than 150 km.