Pb-207-Pb-206, Ar-40-Ar-39 and Apatite Fission-Track Geothermochronology Revealing the Emplacement, Cooling and Exhumation History of the Karacayir Syenite (N Sivas), East-Central Anatolia, Turkey

Abstract

The Karacayir syenite, intruding the Palaeozoic crustal metamorphics and unconformably overlain by Upper Paleocene to Eocene Tokus formation in the north of Sivas (east-central Anatolia), has been studied with respect to Pb-207-Pb-206 single zircon evaporation, biotite Ar-40-Ar-39, and apatite fission-track geothermochronology. Pb-207-Pb-206 single zircon evaporation dating yields an age of 99.0 +/- 11.0 Ma (Cenomanian-Turonian) which is considered to be the intrusion age. Biotite Ar-40-Ar-39 age determination gives a cooling age of ca. 65 Ma. Apatite fission-track dating, combined with T-t modeling based on track-length distribution data, determines a fast tectonic exhumation with an uplift rate of > 1 mm/a which occurred 58-61 Ma ago. This Middle Paleocene fast tectonic uplift is considered to have resulted from a compressional regime induced by the collision between the Tauride-Anatolide platform (TAP) and the Eurasian plate (EP) along the Izmir-Ankara-Erzincan (IAE) suture zone following the closure of the north-dipping subducted IAE ocean which belongs to northern Neo-Tethyan realm. This compressional regime has also formed the peripheral foreland basins in central Anatolia.