Titel: Megathrust shear force limits mountain height at convergent plate boundaries
Armin Dielforder1, Ralf Hetzel2, Onno Oncken3
1Institut für Geologie, Leibniz Universität Hannover, Germany; 2Institut für Geologie und Paläontologie, Westfälische Wilhelms-Universität Münster, Germany; 3GFZ Deutsches GeoForschungsZentrum Potsdam, Germany
Veranstaltung: GeoKarlsruhe 2021
The shear force along convergent plate boundary faults (megathrusts) determines the height of mountain ranges that can be mechanically sustained. Whether the true height of mountain ranges corresponds to this tectonically supported elevation is, however, debated. In particular, climate-dependent erosional processes are often assumed to exert a major control on mountain height, although this assumption has remained difficult to validate. To address this issue, we first constrained the shear force along active megathrusts from their rheological properties and then determined the tectonically supported elevation using a force balance model. This analysis revealed that the height of mountain ranges around the globe matches the tectonically supported elevation, irrespective of climatic conditions and the rate of erosion. This finding indicates that the height of mountain ranges is effectively limited by the megathrust shear force and implies that global differences in mountain height are at first-order tectonically controlled. Temporal variations in mountain height should therefore reflect long-term changes in the overall force balance rather than changes in climate and erosion.
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