LATE CRETACEOUS ARC MAGMATISM IN THE SOUTHERN CENTRAL PONTIDES: CONSTRAINTS FOR THE CLOSURE OF THE NORTHERN NEOTETHYAN BRANCHES
Keywords:andesites, volcanic arc, Neotethys Ocean, geodynamics, Central Pontides, Northern Turkey
The southern Central Pontides in northern Turkey the remnants of two Neotethyan oceanic basins, the Intra-Pontide and the Izmir-Ankara-Erzincan sutures, and the interposing continental microplate, the Sakarya Composite Terrane, are completely dissected by the North Anatolian Shear Zone. Within the resulting kilometer-scale, strike-slip fault-bounded blocks, several Late Cretaceous arc-type magmatic units have been detected. Reconstruct their paleotectonic settings is fundamental to unravel the geodynamic reconstruction of the southern Central Pontides. In this paper, we present new geochemical data from one of these magmatic units, the Yerkuyu Unit, and compare them with those collected from the Tafano Unit, an other arc-type magmatic units bounded by faults of North Anatolian Shear Zone. The studied igneous lithologies have a subduction-related magmatic geochemical signature matching with that of the Tafano Unit. However, the tectonomagmatic characterization highlighted that the Tafano Unit magmatism developed within a continental arc tectonic setting, while the volcanic rocks of the Yerkuyu Unit derived from an oceanic arc magmatism. This finding indicates that the subducted oceanic lithosphere of the the İzmir-Ankara-Erzincan branch of the Neotethys Ocean created oceanic volcanic arcs close to the subduction zone (i.e., the Yerkuyu Unit) and beneath the Sakarya continental microplate (i.e., the Tafano Unit).