Low temperature thermochronology in the Eastern Alps: Implications for structural and topographic evolution

Area of Science:

• Geology
• Tectonics
• Geochronology

Background:

• The southeastern Tauern Window and adjacent Austrolapine units have a complex near-surface history.
• Age-elevation correlations can be misleading for understanding crustal exhumation and cooling.

Purpose of the Study:

• To constrain the near-surface history of the southeastern Tauern Window and Austrolapine units.
• To investigate the drivers of surface uplift and exhumation in the Eastern Alps.

Main Methods:

• Apatite fission track analysis
• Zircon and apatite (U-Th)/He thermochronometry
• Integration of new and existing geochronological data

Main Results:

• Isothermal warping in Penninic footwall units suggests uplift and erosion, with no Middle Miocene exhumation rate increase.
• Austroalpine hangingwall units show increased Paleogene to Neogene exhumation rates without isothermal warping.
• A Middle Miocene exhumation pulse, evidenced by zircon (U-Th)/He and fission track ages, correlates with increased sediment accumulation.
• Enhanced sedimentation and exhumation at the Miocene/Pliocene boundary, seen in Western/Central Alps, are absent in the Eastern Alps.
• Oligocene to Late Miocene fault activity along the Möll valley fault and related structures indicate an extruding wedge in the Eastern Alps.
• Middle Miocene extension across the entire Alpine arc is supported by cooling ages along major normal faults.

Conclusions:

• Surface uplift in the Eastern Alps is more likely driven by tectonic or deep-seated mechanisms than climatic triggers.
• The study refines our understanding of the interplay between fault activity, exhumation, and topography development in the Alps.