Small-Scale Convection Raising East Anatolia and Northern Iran

Abstract:

The East Anatolia and Iranian plateaus (originally referred as a Turkish-Iranian plateau) are characterized by 1.5-2 km average elevation and have been deformed through Alpine-Himalayan continental collision between the Arabian and Eurasian plates. Recent seismological and geological studies suggest that the lithospheric structure between these two plateaus differs significantly since the Zagros fold-thrust belt in western Iran is associated with a thick lithospheric root (up to 225 km) whereas the East Anatolia seems to be lacking its mantle lithosphere. In this work, we use 2-D numerical experiments to test the applicability of small-scale convection model to account for the anomalous topography and uplift across the Turkish-Iranian plateau. Our models are designed to track the evolution of the surface topography as a response to a mantle flow activity in the step like morphology of the lithospheric base as wells as the temperature field. We test the role of several rheological parameters (e.g., viscosity) and variation in the lithospheric thickness in a series of experiments. Modeling results are tested against various observables for eastern Anatolia and Iran such as surface topography, crustal thickness, and surface strain rate. Our results provide new insight in the geodynamic evolution of Alpine type orogenic systems and suggest alternative mechanism to lithospheric delamination and/or slab break-off for the uplift of mountain belts.