Late Cretaceous – recent lithosphere scale evolution of Turkey: linking the crustal surface evolution to the structure of the mantle

Abstract:

Central Anatolia (Central Turkey) possesses all the characteristics of a plateau. It experienced a period of rapid and substantial uplift (late Miocene, ∼8 Ma) while significant crustal shortening did not occur. Similar to other plateaus, the presence of volcanic ash and tuff within the sediments suggest that uplift was preceded by widespread volcanism (∼14-9Ma). The lithospheric context of these events is, however, unknown. For the Eastern Anatolian plateau, similar events have been attributed to southward retread followed by slab break-off of the northern Neotethys slab. Recent tomographic results indicate that this northern Neotethys slab extended beneath both the Eastern and Central Anatolian plateau prior to late Miocene delamination and possibly even beneath western Anatolia prior to the Eocene (?). We propose a new lithospheric scenario for the regional evolution for the Aegean-Anatolia-Near East region that combines a recent compilation of surface geology data with the structure of the upper mantle imaged with tomography.

In our new scenario for the evolution of the Aegean-Anatolia-Near East region, a single continuous subduction zone south of the Pontides (Izmir – Ankara – Erzincan crustal suture zone) accommodated the Africa – Eurasia convergence until the end of the late Cretaceous. In the Late Cretaceous - Eocene the northern Neotethys Ocean closed followed by Anatolide – Taurides (south) and Pontides (north) continental collision along the Izmir – Ankara – Erzincan crustal suture zone. While the trench jumped to the south of Anatolide – Taurides terrane, subduction continued beneath the Izmir-Ankara-Erzincan suture where the northern Neotethys slab continued to sink into the deeper mantle. In the early Miocene (∼20-15Ma), the northern Neotethys slab started to retreat southward towards the trench, resulting in delamination of the lithospheric mantle. The last part of (early Miocene - recent) our scenario is testable. We use a coupled thermal-flexural model of the lithosphere. Model results show that delamination can explain the average present-day long-wavelength topography of the Central Anatolian plateau. For the Eastern Anatolian plateau, delamination explains half the present-day elevation: the other half resulted from crustal thickening.