TECTONIC EVOLUTION OF THE AFRICA/ARABIA–ANATOLIA PLATE BOUNDARIES AND THE CENOZOIC OROGENIC BELTS IN THE EASTERN MEDITERRANEAN REGION

The modern Africa/Arabia–Anatolia plate boundaries are represented by south-facing subduction/collision zones that are part of a broad domain of regional convergence between Eurasia and Afro-Arabia since the latest Mesozoic. The Anatolia plate is made mainly of young orogenic belts (Eocene & Miocene) that evolved during a series of collisions between Gondwana–derived ribbon continents & trench-rollback systems within the Tethyan realm. The collision of the Eratosthenes seamount with the Cyprus trench since the L. Miocene is a smaller-scale example of this accretionary process & has affected the slab geometry–kinematics of the subducting African lithosphere. Tomographic studies show that the uppermost mantle beneath much of the young orogenic belts in Anatolia is anomalously hot & thin, consistent with widespread recent volcanism in western, central & eastern Turkey. In all these areas, crustal extension was under way by the L. Oligocene–Miocene, following the main episodes of microcontinental collisions. Pinning of subduction hinge zones by the accreted ribbon continents arrested slab rollback processes, causing terrane stacking & crustal thickening, and resulted in slab breakoff because of continued convergence of the lithospheric mantle. Slab breakoff–induced asthenospheric upwelling provided the necessary heat & melt to produce the first phases of postcollisional magmatism. Renewed subduction & slab rollback in the Tethyan realm triggered lithospheric–scale extension in the upper plate, and the thermally weakened orogenic crust started collapsing. These processes resulted in rapid exhumation of recently formed high-pressure metamorphic rocks & in the formation of metamorphic core complexes & sedimentary basins. Slab breakoff, lithospheric delamination & slab tearing were common processes that resulted directly from collisions, and caused convective remobilization of the asthenosphere leading to magmatism. Asthenospheric upwelling & partial melting played a major role in a geochemical progression of post-collisional magmatism from initial shoshonitic, calc-alkaline to late-stage alkaline affinities through time. In this talk, I discuss the collision-driven tectonic evolution of the western & eastern Anatolian orogenic belts & provide an overview of their crustal architecture.