Surface waveform tomography of the Turkish-Iranian plateau

The Middle East is a tectonically complex region consisting of terrains as diverse as Precambrian shields and young orogens. The dominant tectonic feature is the Turkish–Iranian plateau, a recently elevated, seismically active region along the Zagros–Bitlis suture, which results from the collision of the Arabian Plate with Eurasia. In this study, we use surface waveform tomography to elucidate the upper-mantle shear wave velocity structure beneath the Turkish–Iranian plateau and adjacent regions. The main large-scale feature in the tomographic model is a low shear wave velocity anomaly in the uppermost mantle beneath the plateau. This low-velocity feature correlates with a long-wavelength free-air gravity anomaly and with recent volcanism whose geochemistry has a lower lithospheric mantle signature. Seismology, gravity and volcanism all suggest the presence of a thin lithosphere and warm upper mantle beneath the Turkish–Iranian plateau. The upper-mantle low shear wave velocity zone, the high free-air gravity and the deep lithospheric source depth for the basaltic volcanism are all consistent with a partial delamination of the lithosphere as a result of earlier lithospheric thickening resulting from the continental collision.