207Pb-206Pb, 40Ar-39Ar and apatite fission-track geothermochronology revealing the emplacement, cooling and exhumation history of the Karaçayir Syenite (N Sivas), East-Central Anatolian, Turkey

Abstract

The Karaçayιr syenite, intruding the Palaeozoic crustal metamorphics and unconformably overlain by Upper Paleocene to Eocene Tokuş formation in the north of Sivas (east-central Anatolia), has been studied with respect to 207Pb-206Pb single zircon evaporation, biotite 40Ar-39Ar, and apatite fission-track geothermochronology. 207Pb-206Pb single zircon evaporation dating yields an age of 99.0±11.0 Ma (Cenomanian-Turonian) which is considered to be the intrusion age. Biotite 40Ar-39Ar 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 İzmir-Ankara-Erzincan (İAE) suture zone following the closure of the north-dipping subducted İAE ocean which belongs to northern Neo-Tethyan realm. This compressional regime has also formed the peripheral foreland basins in central Anatolia. Copyright © TÜBİTAK.