Linking Slab Break-Off, Hellenic Trench Retreat, and Uplift of the Central and Eastern Anatolian Plateaus

Abstract:

The Central and Eastern Anatolian plateaus are integral parts of the world’s third largest orogenic plateau. Geophysical surveys that have provided insights into the crust, lithosphere, and mantle beneath Eastern Anatolia are now accompanied by recent work in Central Anatolia constraining uplift along its northern and southern margins. Together with predictions from geodynamic models, the observations can be integrated to identify probable mechanisms of plateau growth.

A changeover from shortening to extension along the southern margin of Central Anatolia coeval with the start of uplift in the latest Miocene is likely associated with oceanic slab break-off following Arabia-Eurasia collision. This interpretation is supported by tomography, seismicity, and the pattern of uplift. Based on geological observations and model predictions, slab break-off likely occurred first beneath Eastern Anatolia in middle Miocene time and propagated westward toward Cyprus by the latest Miocene. Uplift at the northern margin of Central Anatolia appears to result from crustal shortening starting in the late Miocene, which has been linked to the broad restraining bend of the North Anatolian Fault (NAF). The uplift history of the Central Anatolian interior is unclear, although shortening was superseded by extension in the late Miocene. This change in the deformation style coincides with faster retreat of the Hellenic trench as well as uplift of the northern and southern margins of Central Anatolia.

These different events may be linked, as faster retreat of the Hellenic trench has been predicted to occur after slab break-off, which could have induced extension of Central Anatolia and helped to form the NAF through accelerated westward escape of Anatolia. Overall, geochronologic evidence supports the hypothesis that tectonic and geodynamic plateau-forming activity throughout the Aegean-Anatolian domain in the Miocene defines a series of events that may all be linked to slab break-off.