Tectonostratigraphic evolution of the basins on the southern branch of the North Anatolian Fault System in the SE Marmara Region, Turkey

The lithostratigraphy of the Mekece–Iznik Corridor, the Geyve–Pamukova, and the Iznik basins on the southern branch of the North Anatolian Fault System (NAFS-SB) was investigated in detail. The intra-basin deposits carried by Sakarya River and the drainage systems in the northern and southern elevated blocks of the Iznik and Geyve–Pamukova Basins have been classified based on their lithofacies characteristics. The Geyve–Pamukova basin, which has developed with a NNE–SSW-trending transtensional strain, was formed as a lazy Z-shaped and releasing bend or pure strike-slip, pull-apart basin that is related to simple-shear, right-lateral strike-slip faulting. The Iznik basin was formed by a right-lateral strike-slip faulting kinematics and NNE–SSW-trending transtension as a result of the step-over of the northeast-trending Dırazali fault from the southern edge to the NW-trending Gürle fault, and the western step-over of this fault to the E–W-trending Umurbey fault. This strike-slip setting is also supported by the NW–SE-trending right-lateral oblique normal Orhangazi fault on the northern edge of the basin. According to this, the Iznik basin can be described as a more advanced stage of a large-scale, pull-apart basin compared with a lazy Z-shaped and releasing bend or transtensional strain. Furthermore, it is defined as the former stage of an extreme or rhomboid-type transtensional pull-apart basin.