Datensatz

Zusammenfassung

It is generally accepted that convergence of the Arabian and African plates is a subduction‐dominated process. However, the subduction scenarios are still debatable. Here we present a 3‐D model of the mantle to a depth of 700 km, based on a joint interpretation of the seismic tomography, residual topography, residual mantle gravity field, and seismicity. At the northwestern edge of the collision zone, we only observe partial underthrust of the Eurasian plate under the West Greater Caucasus. We suggest that this is the initial stage of subduction polarity reversal after the break off of the plate formerly subducted northward. To the southeast, counteracting subduction zones are found beneath northwest Zagros in the south and beneath the East Greater Caucasus and Alborz in the north. This scenario is likely the result of highly buoyant and weak blocks of the Lesser Caucasus, Alborz, and northwest Zagros, which are underlain in the south by the Arabian plate and the Scythian plate and South Caspian from the opposite side. Further to the southeast, a delaminated lithospheric slab is observed under southeast Zagros, while the Arabian and Eurasian plates only partially underthrust East Zagros and Kopet Dagh, respectively. In the southern part of the collision zone under Makran, only remnants of the formerly subducted slabs are found below 200 km.