Regional Cenozoic Uplift of Europe from Linear Inverse Modelling of Longitudinal River Profiles
Abstract
The shape of a river profile is controlled by the interplay between uplift and erosion. It is generally accepted that the phenomenological stream power formulation provides a useful basis for determining how this shape evolves as a function of time and space. Typically, erosion is parametrized using two terms. The first term controls the upstream advection of knickzones and assumes that the advective velocity is a function of upstream drainage area and local slope. The second term controls `rock diffusivity', which acts to lower the river profile. In the geomorphological community, the stream power formulation is usually solved by assuming steady state and by plotting upstream drainage area as a function of slope. Here, we use an integrative approach to solve the equation without the need to assume steady state. Previous work has shown that the `rock diffusivity' term, together with the exponent of local slope (i.e. n), can be ignored at long wavelengths. This simplification enables the linear inverse problem to be posed and solved using the method of characteristics. Large inventories (i.e. thousands river profiles) can be inverted to determine regional uplift rate histories as a function of time and space. We present results from an analysis of a Western Eurasian drainage network, consisting of 1,126 river profiles. This region encompasses at least four areas of high elevation where the origin of topography is much debated (i.e. Scandinavia, Spain, Turkey, Italy). Linear inverse modelling yields excellent fits between observed and calculated river profiles. The key erosional parameters were determined using independent geologic observations (e.g. stratigraphic evidence for marine incursions, emergent marine terraces, thermochronologic constraints). Our results suggest that each of these areas has undergone significant regional uplift in Cenozoic times. Since the linearized approach is computationally efficient, it is possible to systematically test the sensitivity of our results to key input parameters (e.g. upstream drainage area, m). This analysis confirms that inverse modelling of large numbers of river profiles yields coherent results and that this general approach is a powerful tool for helping to determine the spatial and temporal evolution of topography.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMEP53B0943M
- Keywords:
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- 1824 Geomorphology: general;
- HYDROLOGYDE: 1862 Sediment transport;
- HYDROLOGYDE: 8020 Mechanics;
- theory;
- and modeling;
- STRUCTURAL GEOLOGYDE: 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS