PRELIMINARY GEOCHRONOLOGICAL CONSTRAINTS ON THE TECTONIC HISTORY OF A MAJOR INTRAPLATE FAULT, DANUBE FAULT, GERMANY

Determining the timing of repeated activity of continental intraplate faults is important to understand geodynamic models and the forces driving lithospheric deformation and mantle convection. A key study area is the Bohemian Massif within the interior of the Eurasian plate with a long intraplate deformation history along significant fault zones, like the NW–SE-striking Bavarian Pfahl and Danube faults. Despite being one of Europe's largest faults, with a prominent escarpment and significant evidence of recent tectonic activity, the timing of the Danube Fault's reactivation episodes is not well established. Therefore, we use a geochronological approach to date synkinematically crystallized minerals, including U-Pb dating of calcite and K-Ar dating of illite. Additionally, we will obtain ⁴⁰Ar/³⁹Ar dates of potassium-bearing minerals in the granitoid host rocks and apply thermochronologic and multi-domain diffusion modeling to ascertain the timing of potential fault-driven system resetting.

The earliest constraint on the Danube fault's initiation is provided by published U-Pb zircon ages of deformed granites (310 to 342 Ma) (Klein et al. 2008 Lithos 102). We anticipate that the K-Ar ages of illite and U-Pb ages of calcite will be significantly younger, indicating possible reactivation. Combined with ⁴⁰Ar/³⁹Ar frictional resetting data, these insights provide a comprehensive understanding of the Danube Fault's dynamic evolution over time. Detailed petrological and geochemical investigations of the host rock and fault surface mineralizations support the interpretation of the radiometric dates.