Abstract
The timing of the transition from paleotectonic contraction to neotectonic escape in the Anatolian microplate remains a subject of intense debate in Mediterranean geodynamics. This study presents the first direct constraints on the reactivation timing of major shear zones within the Central Anatolian Crystalline Complex (CACC) using in-situ laser ablation ICP-MS U-Pb dating of deformation-induced titanite. We targeted the Savcılı Shear Zone, a major crustal-scale deformation corridor cutting across the Late Cretaceous Baranadağ pluton. Microstructural analysis reveals two distinct populations of titanite: coarse-grained, euhedral magmatic titanite showing oscillatory zoning, and fine-grained, recrystallized dynamic titanite aligned with the mylonitic foliation. U-Pb dating of the magmatic cores yields a well-defined lower intercept age of 76.4 ± 1.2 Ma, reflecting the timing of post-collisional pluton crystallization. In contrast, recrystallized rims and syn-kinematic grains from high-strain mylonites yield a distinct Middle Miocene age of 14.2 ± 0.6 Ma. This young age provides direct, unequivocal evidence for ductile-to-brittle shear zone reactivation during the Middle Miocene. We interpret this reactivation as a manifestation of the onset of the modern neotectonic escape regime in Anatolia, driven by the collision of the Arabian plate with Eurasia. These findings demonstrate the utility of titanite U-Pb geochronology in deciphering the overprinted deformation histories of complex crystalline basements.
