Tectonic evolution of the South Tethyan ocean: evidence from the Eastern Taurus Mountains (Elaziğ region, SE Turkey)

Abstract

AbstractGeological information from the Eastern Taurus Mountains, part of the Tethyan (South Neotethyan) suture zone exposed in the Elaziğ region, is used here to test existing tectonic hypotheses and to develop a new tectonic model. Five main tectonic stages are identified: (1) Mid-Late Triassic rifting-spreading of Southern Neotethys; (2) Late Cretaceous northward subduction-accretion of ophiolites and arc-related units; (3) Mid-Eocene subduction-related extension; (4) Early-Mid-Miocene collision and southward thrusting over the Arabian Foreland; (6) Plio-Quaternary, post-collisional left-lateral tectonic escape. During the Late Cretaceous (c. 90 Ma) northward intra-oceanic subduction generated regionally extensive oceanic lithosphere as the İspendere, Kömürhan, Guleman and Killan ophiolites of supra-subduction zone type. A northward-dipping subduction zone was activated along the northern margin of the ocean basin (Keban Platform), followed by accretion of Upper Cretaceous ophiolites in latest Cretaceous time. As subduction continued the accreted ophiolites and overriding northern margin (Keban Platform) were intruded by calc-alkaline plutons, still during latest Cretaceous time. The northern margin was covered by shallow-marine mixed clastic-carbonate sediments in latest Cretaceous-Early Palaeogene time. Northward subduction during the Mid-Eocene was accompanied by extension of the northern continental margin, generating large fault-bounded, extensional basins that were infilled with shallow- to deep-water sediments and subduction-influenced volcanic rocks (Maden Group). Thick debris flows (‘olistostromes’) accumulated along the oceanward edge of the active margin. The partly assembled allochthon finally collided with the Arabian continental margin to the south during Early-Mid-Miocene time in response to oblique convergence; the entire thrust stack was then emplaced southwards over the downflexed Arabian Foreland. Left-lateral strike-slip (tectonic escape) along the East Anatolian Fault Zone ensued.