207Pb-206Pb, 40Ar-39Ar and fission-track geothermochronology quantifying cooling and exhumation history of the Kaman-kirşehir region intrusions, Central Anatolia, Turkey

Abstract

The Kaman-K?rşehir region intrusions were generated in a post-collisional extensional setting following Cenomanian-Turonian docking of an oceanic island arc, comprising the supra-subduction zone (SSZ) Central Anatolian ophiolite (CAO), onto the Tauride-Anatolide Platform (TAP). These granitoids have been named, from N to S, the Çamsar? quartz syenite, Hamit quartz syenite, Bay?nd?r nepheline-cancrinite syenite, Durmuşlu nepheline-nosean-melanite syenite porphyry and Baranada? quartz monzonite. They intrude the crustal metasediments of the Central Anatolian Crystalline Complex (CACC) and CAO and are unconformably overlain by Upper Paleocene to Lower-Middle Eocene sediments. The single-zircon 207Pb-206Pb evaporation age of the Çamsar? unit is 95.7±5.1 Ma; those of the Hamit and Baranada? units are indistinguishable with a weighted mean of 74.3±4.5 Ma. The amphibole 40Ar-39Ar ages of the Hamit and Baranada? units are almost identical with a weighted mean of 72.7±0.1 Ma. The apatite fission-track age vs elevation plot for the Çamsar?, Hamit, Durmuşlu and Baranada? samples reveals rapid exhumation (>1 km/Ma) between ?57 and ?61 Ma, consistent with the results of track-length modelling. This Early-Middle Paleocene rapid exhumation is thought to result from uplift triggered by continent (TAP) - continent (Eurasian plate; EP) collision following the closure of İzmir-Ankara-Erzincan (İAE) ocean that also initiated the formation of peripheral foreland basins in central Anatolia. Copyright © TÜBİTAK.