Late Cenozoic was a period of large-scale extension in the Aegean. The extension is mainly recorded in the metamorphic core complexes with little data from the sedimentary sequences. The exception is the Thrace Basin in the northern Aegean, which has a continuous record of Middle Eocene to Oligocene marine sedimentation. In the Thrace Basin, the Late Oligocene–Early Miocene was characterized by north-northwest (N25°W) shortening leading to the termination of sedimentation and formation of large-scale folds. We studied the stratigraphy and structure of one of these folds, the Korudağ anticline. The Korudağ anticline has formed in the uppermost Eocene–Lower Oligocene siliciclastic turbidites with Early Oligocene (31.6 Ma zircon U–Pb age) acidic tuff beds. The turbidites are underlain by a thin sequence of Upper Eocene pelagic limestone. The Korudağ anticline is an east-northeast (N65°E) trending fault-propagation fold, 9 km wide and 22 km long and with a subhorizontal fold axis. It is asymmetric with shallowly-dipping northern and steeply-dipping southern limbs. Its geometry indicates about 1 km of shortening in a N25°W direction. The folded strata are unconformably overlain by Middle Miocene continental sandstones, which constrain the age of folding. The Korudağ anticline and other large folds in the Thrace Basin predate the inception of the North Anatolian Fault (NAF) by at least 12 myr. The Late Oligocene–Early Miocene (28–17 Ma) shortening in the Thrace Basin and elsewhere in the Balkans forms an interlude between two extensional periods, and is probably linked to changes in the subduction dynamics along the Hellenic trench.

晚新生代是爱琴海大规模扩展的时期。该延伸主要记录在变质岩心复合物中，沉积序列的数据很少。例外是爱琴海北部的色雷斯盆地，该盆地具有中始新世至渐新世海洋沉积的连续记录。在色雷斯盆地，晚渐新世-早中新世的特征是西北-西北（N25°W）缩短，导致沉积的终止和大褶皱的形成。我们研究了其中一种褶皱（Korudağ背斜线）的地层学和构造。Korudağ背斜形成在最上新世-下渐新世硅质碎屑浊积岩中，并具有早渐新世（锆石U-Pb年龄为31.6 Ma锆石）酸性凝灰岩床。浊积岩层系于上新世上层上层石灰岩的薄层之下。Korudağ背斜是东北向（N65°E）趋势断层传播褶皱，宽9 km，长22 km，具有水平下褶皱轴。它是不对称的，北部有较浅的倾斜，南部有较陡的倾斜。其几何形状表示在N25°W方向上缩短了约1 km。褶皱地层被中新世中部陆相砂岩不规则地覆盖，这限制了褶皱的年龄。色雷斯盆地的Korudağ背斜和其他大褶皱早于北安那托利亚断层（NAF）形成至少12 myr。色雷斯盆地和巴尔干其他地区的晚渐新世-早中新世（28-17 Ma）缩短形成了两个伸展期之间的插曲，并且可能与沿希腊海沟的俯冲动力变化有关。