Late Cenozoic tectono-sedimentary evolution of the Ulukışla Basin: progressive basin development in south-central Turkey

The Ulukışla Basin is one of the most important late Cretaceous-Cenozoic basins in central Anatolia. The basin is surrounded by the Bolkar Mountains of Tauride Platform in the south, the Niğde Massif of Central Anatolian Crystalline Complex to the north, and the Ecemiş Fault Zone and Aladağ Mountains in the east. The fact that time interval proposed for the formation of Ulukışla Basin is quite wide and more than one tectonic regime prevailed in the region, have led to various suggestions concerning the evolution of the basin. While the suggestions majorly examine the character of the basin during the late Cretaceous-early Cenozoic, the number of detailed studies on the status of the basin in the late Cenozoic is limited. In this study, we focused on the less-studied late Cenozoic evolution to differentiate the tectonic phases that controlled the development of Ulukışla Basin through structural data, and elaborate the responses of sedimentation and paleogeography during this period through detailed facies analyses. Our findings indicate that the Ulukışla Basin, which started to develop as a supradetachment basin in the late Cretaceous, has continued its extensional development progressively during its Cenozoic history. While the relatively well-studied early Cenozoic sequences represent a marine environment that was rapidly changed shallow- to deep-sea environment and then gained a shallow character by the middle Eocene, sedimentary features and fossil contents of the late Cenozoic units characterize deposition started in a paralic environment changing into a terrestrial environment rapidly, as a result of isolation by the uplifting of surrounding topographies while the basin continues its development under an extensional tectonic regime. However, the extensional basin history surceased in post-middle Eocene and post-middle Miocene, probably caused by the closing processes of the different branches of Neotethys Ocean.