An Example of Post-collisional Magmatism in Northwestern Anatolia: the Kızderbent Volcanics (Armutlu peninsula, Turkey)

Authors: S. Can GENÇ, Yücel YILMAZ

Abstract: The Lutetian-Upper Eocene magmatic association, which crops out in the Armutlu peninsula, NW Anatolia, is a good example of post-collisional magmatism. In this area, the İstanbul-Zonguldak Paleozoic fragment (the Rhodope-Pontide fragment) and the Sakarya continent collided before the Maastrichtian as a result of the total consumption of the northern branch of the Neo-Tethys ocean (the Intra-Pontide ocean) between them. These fragments of the two collided continents were covered collectively by the continental-shallow marine sediments as a common cover during the Maastrichtian. Following the collision a severe magmatic activity occurred during the Lutetian. This magmatism produced felsic, intermediate and basic lavas and the associated pyroclastic rocks, and co-eval high-level granitic plutons emplaced in the volcanic association. The volcanic association has a CA character and displays many similar geochemical features to those of the subduction-related volcanic series. However, the geologic data obtained from the region shows that there was no contemporary subduction system that the magmatic activity could have been associated with. Therefore, the Lutetian magmatic rocks are evaluated to be the products of post-collisional magmatism. The magma is regarded as a derivative of the LIL-enriched mantle source.