Tomographic evidence of slab detachment beneath eastern Turkey and the Caucasus

Abstract

Teleseismic phase readings from the Eastern Turkey Seismic Experiment (ETSE) have been inverted using teleseismic tomography in order to create a 3-D image of the underlying mantle beneath Eastern Turkey. The aim was to investigate the existence of an upper mantle negative velocity anomaly that is used to explain the uplift of Eastern Anatolian plateau and the potential pieces of detached oceanic slabs related to Neo-Tethyan subduction suggested by previous studies. Using teleseismic waveforms from the 29 stations of the Eastern Turkey Seismic Experiment, 2926 direct P phases from 146 events were picked by using adaptive stacking techniques. In order to increase the station coverage and resolve the surrounding area, the phase readings from the International Seismological Center (ISC) Bulletin have also been added. The data set consists of 9571 P and PKP phase readings of 79 stations from 503 teleseismic events. This study develops the first high-resolution 3-D upper mantle P-wave tomographic model for this region. The tomographic results show the existence of an upper mantle negative velocity anomaly to a depth of ∼200 km beneath the eastern Anatolian accreationary complex (EAAC) as commonly observed in the previous studies that suggest a shallow partially molten asthenosphere. The slab-like high velocity anomalies beneath the EAAC, Pontides and Caucasus are interpreted as the detached southern and northern Neo-Tethys slabs.