A post-collision slab-breakoff model for the orgin of the Middle Eocene magmatic rocks of the Armutlu–Almacık belt, NW Turkey and its regional implications
Fatma Gülmez, Ş. Can Genç, Mehmet Keskіn, Okan Tüysüz, 2013. "A post-collision slab-breakoff model for the orgin of the Middle Eocene magmatic rocks of the Armutlu–Almacık belt, NW Turkey and its regional implications", Geological Development of Anatolia and the Easternmost Mediterranean Region, A. H. F. Robertson, O. Parlak, U. C. Ünlügenç
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Middle Eocene magmatic rocks (MEMR) (49.3±2 to 38.1±1.9 Ma) formed an east–west trending belt after continental collision and rest unconformably on pre-Middle Eocene units as a common cover. The origin and tectonic setting of MEMR are controversial as both arc and post-collisional settings are proposed. We present new geological and petrological data from the western part of the belt, between the Armutlu Peninsula and the Almacık Mountains. The MEMR are represented by basic to intermediate volcanic rocks, dykes and coeval granites. The lavas exhibit a continuous trend from basalt to dacite. The MEMR as a whole display low- to medium-K subalkaline (to rarely mildly alkaline) affinities and a calc-alkaline trend. On N-type Mid Ocean Ridge Basalt-normalized spidergrams these rocks display relative enrichment in large ion lithophile elements, slight enrichment in light rare earth elements, but depletion in Ta and Nb. Geochemical data and Sr, Nd, Pb and δ18O isotope compositions, coupled with ɛNd(T) values, reveal that the MEMR magma was of hybrid type, with both depleted sub-continental lithospheric mantle and crustal components. We conclude that the MEMR was produced in a post-collisional setting, and we favour a slab-breakoff mechanism to explain this as it is consistent with the known Middle Eocene tectonic evolution of northwestern Turkey.
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Geological Development of Anatolia and the Easternmost Mediterranean Region
Anatolia and the easternmost Mediterranean region, especially Turkey, Cyprus and northern Syria, represent an excellent natural laboratory for the study of fundamental geological processes (e.g. rifting, seafloor spreading, ophiolite genesis and emplacement, subduction, exhumation and collision). Their interaction has created an intriguing array of deep-sea basins, microcontinents and suture zones.
The volume’s 22 papers include a large amount of new field-based information (much of it multidisciplinary and the product of teamwork). After an overview, the volume is divided into four sections: Late Palaeozoic–Early Cenozoic of the Pontides (northern Turkey); Late Palaeozoic–Early Cenozoic of the Taurides–Anatolides (central and southern Turkey); Late Cretaceous–Pliocene sedimentary basins and structural development (central Anatolia to the Mediterranean); Late Miocene–Recent Neotectonics (southern Turkey, Cyprus and northern Syria).
The volume will interest numerous academic researchers, those concerned with resources (e.g. hydrocarbons; mineral deposits) and also hazards (e.g. earthquakes), as well as advanced undergraduate and postgraduate students.