EGU2020-9714
https://doi.org/10.5194/egusphere-egu2020-9714
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Neogene Exhumation History along TRANSALP: Insights from Low Temperature Thermochronology and Thermo-Kinematic Models

Paul R. Eizenhöfer1, Christoph Glotzbach1, Lukas Büttner1, Jonas Kley2, and Todd A. Ehlers1
Paul R. Eizenhöfer et al.
  • 1Dep. of Geosciences, Tübingen University, Tübingen, Germany
  • 2Geoscience Centre, Göttingen University, Göttingen, Germany

Many convergent orogens such as the eastern European Alps display an asymmetric doubly-vergent wedge geometry. Loci of deepest exhumation are located above the overriding retro-wedge, whereas increased fault activity occurs in the pro-wedge on the subducting plate. The main drainage divide separates steeper from more gently sloping topography on the two wedges of different critical taper. We performed apatite and zircon (U-Th)/He analyses densely spaced along the TRANSALP geophysical transect in combination with thermo-kinematic models based on cross-section balancing. Our new low temperature thermochronology data and thermo-kinematic model results underline (i) deepest levels of exhumation across the Tauern Window until the Pliocene and (ii) higher Late Neogene exhumation rates south of the Periadriatic Fault relative to the north, while seismic activity is focussed across the Southern Alps. Our proposed mantle-to-surface link positions the retro-wedge north of the Periadriatic Fault subsequent to subduction polarity reversal during continental collision. Present-day drainage divide migration trends and imaged locations of mantle-lithospheric slabs beneath TRANSALP suggest ongoing, slow slab reversal since Adriatic indentation in the Eastern Alps. 

How to cite: Eizenhöfer, P. R., Glotzbach, C., Büttner, L., Kley, J., and Ehlers, T. A.: Neogene Exhumation History along TRANSALP: Insights from Low Temperature Thermochronology and Thermo-Kinematic Models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9714, https://doi.org/10.5194/egusphere-egu2020-9714, 2020

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Presentation version 1 – uploaded on 23 Apr 2020
  • CC1: Comment on EGU2020-9714, Ernst Willingshofer, 07 May 2020

    Interesting presentation, though I think that in your balancing work the doming of the Tauern window is too late. There is plenty of geological and geochronologic data that suggest that TW folding is Late Oligocene or even early Oligocene as suggested by dykes of 30 Ma intruding into a steep foliation at the southern margin of the Tauern window.

    Anyhow, I am wondering how you cope with the orogen-parallel deformation when reducing the problem to a 2d section?

    • AC1: Reply to CC1, Paul Eizenhöfer, 07 May 2020

      Hi Ernst,

      thanks a lot for your input. Your point will definitely be included and discussed while working on the section.

      Yes, you're right, Tauern duplexing / doming starts earlier and this is not readily visible in the kinematic model shown in Fig. 4. Strictly speaking, we only show the kinematic evolution and displacement along faults that are relevant to the observed thermochronometer distribution. Even though the earliest phases of duplexing / doming are not shown in the model, it doesn't mean they haven't taken place. It's unlikely that these affected low-temperature thermochronometers such as the ones we employed (AHe, ZHe). Perhaps MAr could preserve a signal of this early phase... Imagine another horse on top of the shown dome further south, even though we didn't actually included it kinematically. In a final version of the figure, we'll add this.

      Unfortunately, we had to 'ignore' orogen-parallel deformation. However, our thermo-kinematic models clearly separate the evolution north and south of the Periadriatic Fault. One can imagine that back in time the northern and southern part of the thermo-kinematic model took place laterally displaced. This will be discussed in our eventual publication.