Long-wavelength late-Miocene thrusting in the north Alpine foreland: implications for late orogenic processes

In this paper, we present new exhumation ages for the imbricated proximal molasse, i.e. Subalpine Molasse, of the northern Central Alps. Based on apatite (U-Th-Sm)/He thermochronometry, we constrain thrust-driven exhumation in the Subalpine Molasse between 12 and 4 Ma. This occurs synchronously to t...

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Bibliographic Details
Published in:Solid earth (Göttingen) 2020-10, Vol.11 (5), p.1823-1847
Main Authors: Mock, Samuel, von Hagke, Christoph, Schlunegger, Fritz, Dunkl, István, Herwegh, Marco
Format: Article
Language:English
Subjects:
Apatite
Basins
Belts
Crystal structure
Crystallinity
Deformation
Dynamics
Earth science
Fault lines
Geological time
Geology
Kinematics
Lakes
Massifs
Miocene
Mountains
Orogeny
Plate tectonics
Sedimentary basins
Stratigraphy
Wavelength
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Summary:In this paper, we present new exhumation ages for the imbricated proximal molasse, i.e. Subalpine Molasse, of the northern Central Alps. Based on apatite (U-Th-Sm)/He thermochronometry, we constrain thrust-driven exhumation in the Subalpine Molasse between 12 and 4 Ma. This occurs synchronously to the main deformation in the adjacent Jura fold-and-thrust belt farther north and to the late stage of thrust-related exhumation of the basement massifs (i.e. external crystalline massifs) in the hinterland. Our results agree with other findings along the north Alpine foreland. While site-specific variations in the mechanical stratigraphy of the molasse deposits influence the pattern of thrusting at the local scale, we observe that late-Miocene thrusting is a long-wavelength feature occurring along the north Alpine foreland roughly between Lake Geneva and Salzburg. The extent of this thrusting signal as well as the timing suggests that late-Miocene thrusting in the north Alpine foreland coincides with the geometries and dynamics of the attached Central Alpine slab at depth. Interestingly, this implies that the slab geometry at depth does not coincide with the boundary between the Eastern and Central Alps as observed in the surface geology. Using this observation, we propose that thrusting in the Subalpine Molasse and consequently also the late stage of thrust-related exhumation of the external crystalline massifs, as well as the main deformation in the Jura fold-and-thrust belt are at least partly linked to changes in slab dynamics.
ISSN:1869-9529
1869-9510
1869-9529
DOI:10.5194/se-11-1823-2020