The timing of metamorphism of the crystalline massifs in western and central Turkey (Menderes, Kirşehir, Niǧde, Akdaǧ) is important information for understandilng the assembly of Anatolia and the thermal-tectonic evolution of the Turkish segment of the Alpine-Himalayan belt. The high-grade basement rocks of the massifs are polymetamorphic, and the complexity of interpreting ages obtained from zircon and other minerals has led to a longstanding debate about the significance and regional extent of Neoproterozoic v. younger (Mesozoic, Cenozoic) metamorphism. New U-Pb SHRIMP (sensitive high-resolution ion microprobe) analyses of monazite from a garnet-sillimanite gneiss in the Kirşehir Massif, central Anatolia, document Late Cretaceous (84.1 ± 0.8 Ma) high-temperature metamorphism. This Late Cretaceous age for central Anatolian metamorphism is at least 50 Ma older than Alpine metamorphism in the Menderes Massif in western Turkey. Models that propose a continuous Anatolide-Tauride tectonic zone, with central Anatolia as a promontory, cannot explain such a large time difference within a small region. Unless the Menderes ages have been reset by Aegean thermal-tectonic events, Anatolia probably formed from a collage of continental fragments rather than by simple collision of an irregular Tethyan platform with Eurasia.
- Central Anatolian Crystalline Complex
- Kirşehir Massif