Fig. 1

a Tectonic map of the northeastern Mediterranean region showing the major sutures and continental blocks and the location of the study areas in the Central Sakarya Basin (1) and Arabian Platform margin (2) (map simplified from Okay & Tüysüz, 1999). b Geological map of the Epçeler, Nallıhan region and lithostratigraphic log of the upper part of the Seben Formation and the Taraklı Formation (map simplified from MTA 2011). Sampling points in Epçeler A and B sections are shown