Long Wavelength Progressive Plateau Uplift in Eastern Anatolia Since 20 Ma: Implications for the Role of Slab Peel-Back and Break-Off

Stratigraphic evidence is used to interpret that the East Anatolian Plateau with 2 km average elevation today was below sea level ~20 Ma and uplift began in the northern part. The presence of voluminous volcanic rocks/melt production across the plateau—younging to the south—corroborates geophysical interpretations (e.g., high heat flow and lower seismic velocities) that suggest progressive removal of the slab subducting under the Pontides. Here, we conduct numerical experiments that investigate the change in the surface uplift as a response to slab peel-back and potential break-off processes under subduction-accretionary complexes as well as continental lithosphere. Model results show similar types of tectonic behavior and magnitudes of uplift-subsidence in both oceanic and continental removal processes, and they satisfactorily explain 1.5 km of plateau rise and a ~280 km wide asthenospheric upwelling zone beneath Eastern Anatolia over 18 Myr timescale. Parametric investigation for varying plate strength and convergence velocities show that such model parameters control the amount of surface uplift (1 to 3 km), the width of the asthenospheric upwelling zone, and the potential timing/depth of break-off of the steepening/peeling slab. Experiments show that slab break-off develops during the terminal phase, which may correspond to only a few million years ago. Therefore, the long wavelength plateau uplift and magmatism over the Eastern Anatolian-Lesser Caucasus region since 20 Ma is controlled by progressive slab peel-back and resulting mantle dynamics. The slab break-off process (if it happened) has yet an indiscernible role.