Differential uplift on the boundary between the Eastern and the Southern European Alps: Thermochronologic constraints from the Brenner Base Tunnel

Abstract

The Brenner Base Tunnel will connect Innsbruck (Austria) and Franzensfeste (Italy) by piercing two of the most important fault structures of the Alps: the Periadriatic fault system (PFS) and the Southern limit of Alpine metamorphism (SAM). (U‐Th)/He dating (apatite) and fission‐track analysis (apatite and zircon) on samples taken during excavation reveal a complex pattern of exhumation through time. The results yield temporal constraints for relative vertical block movement and fault activity. Furthermore, they indicate differential uplift of the northern block along the ~E–W striking PFS and allow locating the position of the SAM in the overtilted nappe stack south of the Tauern Window. Our data strongly support, for the first time, an ongoing north‐side‐up movement along this section of the PFS until at least the end of Miocene.

Thermo‐Kinematic Evolution of the Eastern European Alps Along the TRANSALP Transect

“…The continuity of ages in these thermochronometer systems across the PF implies that only minor vertical displacement could have occurred since at least the Eocene/Oligocene due to the absence of any visible spatial offset of thermochronometer ages across the fault. This observation has been confirmed by recent studies along the Brenner Base Tunnel (Klotz et al, 2019). AFT ages across the Dolomites (Heberer et al, 2017;Zattin et al, 2006) range between ∼24 and ∼9 Ma.…”

Quantifying Tectonic and Glacial Controls on Topography in the Patagonian Andes (46.5°S) From Integrated Thermochronometry and Thermo‐Kinematic Modeling

“…These patterns contain sharp transitions between young thermochronometric ages in the footwall and inherited older ages toward the foreland (including ages from high-temperature systems, e.g., Lock & Willett, 2008;Rak et al, 2017). Furthermore, similar steep gradients in thermochronometric ages (U-shaped age pattern) are observed to be associated with strike-slip faulting, such as the LOFZ in the Northern Patagonian Andes (Thomson, 2002;Thomson et al, 2010) or the Giudiacare and Periadriatic faults in the Alps (Klotz et al, 2019;Pomella et al, 2012). In light of these observations, our hypothesis of tectonically induced, differential exhumation is reasonable.…”

Reuniting the Ötztal Nappe: the tectonic evolution of the Schneeberg Complex

“…8h; Viola et al 2001). This was related to northward indentation of Adria along the Giudicarie Fault System (Viola et al 2001;Pomella et al 2012;Klotz et al 2019)…”

“…Further north the Ötztal and Meran-Mauls units are separated by the NW-dipping Jaufen Fault (Spiess 1995), which acted as a Miocene, top-to-NW normal fault (Pomella et al 2012) after Late Cretaceous, top-to-SE normal faulting and rotation (Viola et al 2001;Pomella et al 2016). The W-dipping Brenner Normal Fault System, activated by the Miocene Tauern Window doming and E-W crustal extension, separates the Ötztal Nappe from the Lower Austroalpine and Penninic nappes in the East (Selverstone 1988;Behrmann 1988;Fügenschuh et al 2000;Rockenschaub and Nowotny 2011;Klotz et al 2019).…”