ISTerre seminar

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U-Th and U-Pb Carbonate Geochronology of Fault Zones: From Tectonic Evolution of the Central Taurides (Türkiye) to Paleo-Fluid Flow in the Bristol Channel Basin (UK)

Friday 24 October 2025 - 11h00

Tunahan Aykut - Université de Pau et des Pays de l’Adour
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Carbonates found in fault zones are more than just secondary minerals; they are natural archives that record both the timing of tectonic deformation and the history of fluid circulation. By applying U–Th and U–Pb geochronology, we can directly constrain when faults slipped and when fluids moved through the crust. In this talk, I will first present results from the Central Taurides in the southern margin of the Central Anatolian Plateau (Türkiye), on the upper plate of the Cyprus Subduction Zone. Here, U–Th carbonate ages from syn-tectonic calcites show continuous normal faulting from >500 ka to the Holocene, with a pronounced cluster around 450 ka that coincides with ~1.5 km of rapid plateau uplift. These results provide the first direct evidence that normal faulting and surface uplift were coeval, linking upper-crustal deformation to deep mantle processes such as slab tearing and asthenospheric upwelling. In addition, U–Pb dating of fault-related calcites reveals a multi-phase tectonic evolution from Late Cretaceous thrust-reverse faulting, through Oligocene strike-slip shearing, to Miocene–Quaternary normal faulting, providing direct isotopic evidence for the long-term brittle history of the southern Central Anatolian Plateau. I will then turn to my ongoing postdoctoral research, which explores how U–Pb carbonate geochronology can be applied to reconstruct the cyclicity of paleo-fluid circulation and to determine the sealing versus conduit history of normal faults in shale-rich caprocks, with direct implications for CO₂ storage and inferences on the tectonic evolution and reactivation of the Bristol Channel Basin in southwest England. Taken together, these case studies illustrate the role of carbonate geochronology as a powerful tool for resolving active deformation and long-term tectonic evolution, as well as a framework for applied questions such as fault zone permeability and the long-term security of CO₂ storage.

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Organizing team : Cycle sismique et déformations transitoires

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/92956342169?pwd=atRbmXkR3hcDaXyMw5rsnD8AbkUqdG.1