^{207}Pb-^{206}Pb, ^{40}Ar-^{39}Ar and Fission-Track Geothermochronology Quantifying Cooling and Exhumation History of the Kaman-Kırşehir Region Intrusions, Central Anatolia, Turkey

Abstract

The Kaman-Kırşehir 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 Çamsarı quartz syenite, Hamit quartz syenite, Bayındır nepheline-cancrinite syenite, Durmuşlu nepheline-nosean-melanite syenite porphyry and Baranadağ 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 ^{207}Pb-^{206}Pb evaporation age of the Çamsarı unit is 95.7±5.1 Ma; those of the Hamit and Baranadağ units are indistinguishable with a weighted mean of 74.3±4.5 Ma. The amphibole ^{40}Ar-^{39}Ar ages of the Hamit and Baranadağ units are almost identical with a weighted mean of 72.7±0.1 Ma. The apatite fission-track age vs elevation plot for the Çamsarı, Hamit, Durmuşlu and Baranadağ 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.