Tu È rkiye Petrolleri A.O. (TPAO) Genel MuÈ duÈ rluÈ g AE uÈ , Arama Grubu, Mu È dafaa Caddesi No. 86, Esentepe, TR-06520 Ankara, Turkey In central Anatolia there are several important basins developed mainly after closure of the northern branch of Neotethys. These are the Haymana, TuzgoÈ luÈ , UlukõsË la, Kõzõlõrmak, C Ë ankõrõ-C Ë orum and Sivas basins. The Sivas Basin is located in the eastern part of central Anatolia between the Central Anatolian Crystalline Complex (CACC) in the north and Taurides in the south. The basement to the southeastern part of the basin consists of recrystallized limestone and clastics of the Permian±Lower Cretaceous BuÈ nyan Metamorphics. These units are overlain by an Upper Cretaceous ophiolitic olistostrome that is overthrust by ophiolites and high pressure±low temperature metamorphic rocks. Lower Palaeocene cover units unconformably overlie this sequence. The basement to the northwestern part is constituted by CACC that includes a high temperature±low pressure polymetamorphic succession of Palaeozoic±Mesozoic age, overthrust by ophiolites and intruded by Upper Cretaceous post-collisional granitoids and syenitoids. The uppermost Maastrichtian±Palaeocene continental to shallow marine (lagoonal) unit unconformably overlies this unit. Upper
Cretaceous±Palaeocene siltstone, shale, pelagic limestone, volcaniclastic rocks and basic volcanic rock intercalations of a within-continental-plate eruptive setting have also been developed on the basement unit. These sequences represent the products of an extensional episode during Late Cretaceous±Palaeocene times in the region between the Taurides and CACC. The Middle Eocene is represented by a regional transgression which was followed by a compressional episode evidenced by thrust faults at the margins and continued regression in the central part of the basin. This compressional period continued up to the end of the Early Miocene. Units formed during this episode are overlain by Upper Miocene±Quaternary continental units intercalated with volcanic rocks formed in fault-controlled extensional basins. It is suggested that the palaeotectonic events were the result of terminal closure of the northern branch of Neotethys. However, the neotectonic events are the result of the collision of the Arabian Plate and Anatolides which causes a westward escape of the Anatolian Plate.