Clocking the entire lifecycle of a Tethyan detachment with structurally-controlled calcite geochronology

Carbonate precipitation spans almost the entire geologic timescale and takes place in various environments including in marine, lacustrine, and hydrothermal systems. When accompanying tectonic processes, carbonate precipitates as vein filling, breccia cement and fault coating, or as mylonitic shear fabrics. These fabrics hold critical information for understanding the formation and timescales of faulting and the migration of fluids. Recent analytical advances make it possible to obtain in-situ U-Pb ages of low U-concentration rocks (<10 ppm) and date diagenesis and deformation of calcite using laser ablation ICP-MS. The direct dating of tectonic fabrics is valuable, yet challenging, especially in regions with a multi-phase tectonic history. This study provides the first in-situ geochronological constraints of the ductile to brittle lifecycle of a carbonate hosted shear zone. The Ivriz Detachment bounds the Central Anatolian extensional province in the Eastern Mediterranean and is responsible for the structural attenuation of the overriding plate during closure of the Neotethys Ocean. Here we report in-situ U-Pb ages that constrain the timing of various events from carbonate deposition in the Jurassic to ductile shearing in the Paleocene, Eocene brittle deformation, and lastly, Oligocene footwall exhumation and fluid flow. Our results demonstrate the timescales of fault movement along a large extensional shear zone can span nearly 30 Myr. Calcite U-Pb geochronology coupled with structural analysis is able to clock the entire lifecycle of shear zones across the brittle-ductile transition.