A Snapshot of Eastern Mediterranean Lithosphere and Upper Mantle: Clues for the Demise of Tethys Ocean
Dr. Berk Biryol, University of North Carolina at Chapel Hill
The tectonics of the Mediterranean region is characterized by an intricate configuration of arcuate subduction zones and mountain belts. The evolution and the geodynamics of these zones are controlled by closure of Tethys Ocean between converging Eurasia and Africa. The interplay between convergence-related compression and slab rollback related extension is further complicated by processes such as termination of subduction, tearing and detachment of subducting oceanic lithosphere. Our recent studies using various seismological techniques reveal the complexity of lithospheric and upper mantle structures in the Anatolian region using a dataset composed of over 200 seismic stations.
Our body-wave tomography results reveal segmented layout of the Aegean and the Cyprus slabs that are separated from each other by a tear as wide as 300 km beneath Western Anatolia. The geometry of this tear suggests it was formed by differential subduction and rollback rates along the Aegean and Cyprus trenches. This configuration of slabs and the associated geodynamic setting is consistent with our upper mantle seismic anisotropy observations from shear-wave splitting measurements favoring a SW direction of asthenospheric flow. We infer that this flow is controlled by the differential forces acting on the upper-mantle, exerted by the slab-roll-back taking place along the Aegean and the Cyprean Subduction Zones. The gaps associated with the slab tears and edges are occupied by slow velocity material and underlie major volcanic provinces of Anatolia. Recent ambient noise tomography results reveal the fragmented nature of the Anatolian lithosphere with seismic velocity variations across paleo-suture zones and major active-tectonic features such as the North Anatolian Fault Zone.
Overall, our observations hold important clues about the effects of Tethys Ocean closure on the structure of subduction zones and lithosphere in the eastern Mediterranean.
|Last updated||Key Points|