The Role of Slab Delamination and Break-off of a "Double-Slab" Set-up Beneath the Eastern Anatolia Convergent Zone

Eastern Anatolia is a major continental collision zone, formed through Alpine-Himalayan orogenic activity. The convergence between the Arabian and Eurasian plates has lifted and shortened the East Anatolian plateau (EATP), resulting in an average plateau elevation of 2 km and development of the deformed Bitlis-Zagros suture zones (BZSZ). Recent seismological and geochemical studies have revealed that the EATP seems to be lacking mantle lithosphere in the north; in the south slab detachment/break-off has been interpreted beneath the suture zone (BZSZ). So far, proposed geodynamic modeling studies have considered the role of these two separate northward dipping slabs independently in order to explain the plateau uplift and the formation of the suture zone (BZSZ). The southward migration of the volcanism and uplift history through mantle lithosphere delamination seem compelling, though an alternative explanation of slab break-off has been suggested and seems consistent with tomographic and thermal constraints. Here, we consider a model solution space that encompasses this tectonic configuration and present a series of scaled thermo-mechanical numerical experiments with concurrent delamination and slab detachment/break-off. We test the role of changing convergence velocities of the lithospheric plates as well as various lower crustal rheological parameters. The modeling results are compared with observational constraints for eastern Anatolia such as surface topography, crustal thickness, and surface strain rate. While considering the larger scale geodynamic setting of eastern Anatolia, we suggest that delamination has played a first order distinctive role for the plateau uplift, magmatic activity and surface deformation in the Eastern Anatolia region.