Late cenozoic evolution of the Ulukisla basin

The Ulukışla Basin is one of the most important basins in Central Anatolia that developed during the Late Cretaceous-Cenozoic. The basin is bounded in the southern side by the Bolkar Carbonate Platform, to the northern side by the Niğde Massif, and in the eastern side by the Ecemiş Fault Zone. In previous studies related to development of the Ulukışla Basin, various views have been suggested because of the age range which is fairly broad for the evolution of the basin, and the region has been effected by numerous tectonic regimes. Additionally, all these suggestions discuss the basin development in the Late Cretaceous-Early Cenozoic time, in other words, detailed studies about the basin development in the late Cenozoic are limited. It is aimed to identify the tectonic regimes that were influential in the development of the Ulukışla Basin during this period when the Neotectonics of Turkey has been formed, the state of sedimentation in this period and the role of the development of the basin within the regional geology. Considering the fossil contents and lithological features of the Cenozoic units, there was a transition from Late Cretaceous shallow marine environment to deeper marine environment. In the Middle Eocene, there was a shallow sea environment. The study area has been completely terrestrial after the late Neogene. According to field observations, it was understood that the structure between the Bolkar Mountains and the basin deposits is a north dipping low angle normal fault, which was effected in the basin development process from the Late Cretaceous to Middle Eocene. The data obtained during the field and remote sensing studies show that the NE-SW, NNE-SSW and ENE-WNW trending faults and lineaments are dominated in the study area and coherent to the main faults and fold axes in the region. As a result of the evaluation of all the present findings, the Ulukışla Basin was exposed under an extensional regime in the Late Cretaceous-Middle Eocene. After the Middle Eocene, significant folds was developed under the effect of a N-S-directed compression in the region, and the normal faults which were developed by the previous extensional phase were cut by reverse faults. Subsequently, during the Oligocene-Middle Miocene period, under the influence of a new extensional regime the deposition was continued. In the Middle Miocene, a relatively weaker last compressional phase was occurred, which caused the folding and faulting of the Oligocene-Middle Miocene units with lower angles. In the Late Miocene-Pliocene, a fault-controlled thick sequence was deposited under the extensional regime in the region. The Quaternary units were unconformably deposited on the Neogene deposits, particularly in the current Ereğli Plain, under the control of the Niğde Fault, which is a normal component left lateral strike-slip fault.