Evolution of the Bayramic magmatic complex, northwestern Anatolia

During the Oligocene-Middle Miocene period widespread magmatic activity developed in Western Anatolia, following the continental collision between the Sakarya continent and the Tauride-Anatolide platform. This produced both intrusive and extrusive rocks, which appear to be associated in space and time, as exemplified from the Bayramic area. In the Bayramic area, the magmatic activity started with the intrusion of the Evciler granite, and the coeval lower volcanic association. This was followed by the development of the upper volcanic association. These rock groups form collectively the Bayramic magmatic complex, which was generated under an on-going north-south compressional regime. The Bayramic magmatic complex has a subalkaline composition, displaying a calcalkaline trend. Trace elements and REE contents resemble to island-are and collision-related magmas. According to the isotope values the Bayramic magmatic complex was derived from the magmas of lithospheric mantle origin, which were later contaminated, while passing through the thick continental crust, in a post-collisional tectonic setting, during the Oligocene-Early Miocene period. The latest product of the magmatism is the Late Miocene-Pliocene basalt lavas. Their geochemical properties are clearly different from the Oligocene-Early Miocene magmatic rocks. The basalts were generated when the north-south compression gave way to the north-south extensional regime. (C) 1998 Elsevier Science B.V. All rights reserved.