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Glacial Carving versus Tectonic Forcing. Documenting their Relative Contribution to Relief Formation

Applicant Champagnac Jean-Daniel
Number 143165
Funding scheme Ambizione
Research institution Geologisches Institut ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geology
Start/End 01.10.2012 - 30.09.2013
Approved amount 133'253.00
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All Disciplines (2)

Discipline
Geology
Other disciplines of Earth Sciences

Keywords (7)

Alps; Quaternary climate; Alaska; Glacial Erosion; Tectonics; Valley formation ; Relief

Lay Summary (English)

Lead
Lay summary
The formation of relief in mountains comes from the complex interact between tectonic forcing of the lithosphere (tectonics which drives rocks motion), and atmospheric processes (climate), that affect erosion, which in turn removes material inhomogeneously from a mountain belt. Landscape is at the interface, and the topography evolves depending on the conditions of climate, tectonics, and erosion.

In this project I work on the importance of the relative contribution of the tectonic and the climate to create relief in mountain ranges.

During the Plio-Quaternary (since ~5Ma), the climate became progressively colder and potentially more erosive, with glaciers periodically covering large parts of the northern hemisphere high-latitude/ high-altitude areas. The effects of these climate changes on mountain building have been studied in detail since a couple of decades. However, because glacial erosion are less well understood than fluvial erosion, the role and importance of glacial erosion in shaping landscapes and in changing relief is still disputed. Specifically, the onset, the timing and the importance of glacial valley carving in alpine region is still largely unknown.

The present project focuses on two natural laboratories that present extreme topography, with different precipitation and glaciers that shape the landscape. They are 1) the St Elias Range in Alaska, where tectonic forcing is high, with a high erosion rate affected by fastmoving temperate glaciers, and 2) the Western and Central Alps, where tectonic forcing is slow, with a moderate glacier cover today, but was almost complete during glacial advances. These areas also show contrasting precipitation gradients, with a spatial variation up to a factor of 20 in the St Elias Range, and only threefold in the Alps.

To achieve this study, I rely on three independent methods, that all aim to derive a
complete history of relief formation and glacial valley carving in response to climatic and
tectonic changes:
1) Terrestrial Cosmogenic Nuclide (TCN) concentrations in rock and sediments to
document the time necessary to erode the upper ~2 meter of rock. In-situ and watershed averaged erosion rates will be quantified, over typical timescales of 500 yrs to 5 kyrs.
2) A new very-low thermochronometer based on Optically Stimulated Luminescence
(OSL) dating, with an exceptionally low closure temperature (30°C – 40°C) has been used to document the latest cooling event, in the upper ~1km of crust, and therefore quantify valley carving and relief evolution over typical a timescale of 50 kyrs to 500 kyrs..
3) Numerical modelling of fluvioglacial landscape evolution, parameterized with
existing and acquired data, will document the erosion behaviour of studied ranges under variable external and internal forcing. Numerical models provided a quantitative and self-consistent scenario for Quaternary relief development and the role of glaciations, and show that glacial erosion lead to dramatic relief increase at valleyscale.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Spatial and temporal variations of glacial erosion in the RhÔne valley (Swiss Alps): Insights from numerical modeling
Sternai Pietro, Herman Frédéric, Valla Pierre G., Champagnac Jean Daniel (2013), Spatial and temporal variations of glacial erosion in the RhÔne valley (Swiss Alps): Insights from numerical modeling, in Earth and Planetary Science Letters, 368, 119-131.
The growth of northeastern Tibet and its relevance to large-scale continental geodynamics: A review of recent studies
Yuan DaoYang, Ge WeiPeng, Chen ZhenWei, Li Chuanyou, Wang ZhiCai, Zhang HuiPing, Zhang Peizhen, Zheng DeWen, Zheng WenJun, Craddock William H., Dayem Katherine E., Duvall Alison R., Hough Brian G., Lease Richard Oliver, Champagnac Jean Daniel, Burbank Douglas W., Clark Marin Kristen, Farley Kenneth A., Garzione Carmala N., Kirby Eric, Molnár Peter H., Roe Gerard H. (2013), The growth of northeastern Tibet and its relevance to large-scale continental geodynamics: A review of recent studies, in Tectonics, 32, 0.
3D cartographic modeling of the Alpine arc
Vouillamoz Naomi, Sue Christian, Champagnac Jean Daniel, Calcagno Philippe (2012), 3D cartographic modeling of the Alpine arc, in Tectonophysics, 579, 131-143.
Pre-glacial topography of the European Alps
Sternai Pietro, Herman Frédéric, Champagnac Jean Daniel, Fox Matthew R., Salcher Bernhard C., Willett Sean D. (2012), Pre-glacial topography of the European Alps, in Geology, 40(12), 1067-1070.
River drainage patterns in the New Zealand Alps primarily controlled by plate tectonic strain
Castelltort Sébastien, Goren Liran, Willett Sean D., Champagnac Jean Daniel, Herman Frédéric, Braun Jean (2012), River drainage patterns in the New Zealand Alps primarily controlled by plate tectonic strain, in Nature Geoscience, 5(10), 744-748.
Tectonics, climate, and mountain topography
Champagnac Jean Daniel, Molnar Peter H., Sue Christian, Herman Frédéric (2012), Tectonics, climate, and mountain topography, in Journal of Geophysical Research B: Solid Earth, 117(2), 0.
Late-Cenozoic relief evolution under evolving climate: Review of quantitative arguments and implications for erosion dynamics
Champagnac Jean-Daniel, Valla Pierre, Herman Frédéric, Late-Cenozoic relief evolution under evolving climate: Review of quantitative arguments and implications for erosion dynamics, in Tectonophysics.

Collaboration

Group / person Country
Types of collaboration
University of Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
University of Boulder, Colorado United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
University of Tübingen Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
University of Grenoble France (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Associated projects

Number Title Start Funding scheme
126408 Glacial Carving versus Tectonic Forcing. Documenting their Relative Contribution to Relief Formation 01.10.2009 Ambizione
119785 Quantification of surface erosion at the northern foothills of the Alps of central Switzerland and identification of potential controls 01.04.2008 Project funding
120502 TOPOALPS - 4D kinematics of the Neogene western Alps (IP2) 01.06.2008 Project funding (special)
120539 Thermo-Europe - Coupled climatic/tectonic forcing of European topography revealed through thermochronometry (IP6) 01.09.2008 Project funding (special)
127127 OSL-thermochronology: development and applications of a new thermochronometer of exceptionally low closure temperature 01.02.2010 Project funding
121578 A 4D Model of Neogene Exhumation in the Central Helvetic Alps 01.10.2008 Project funding

Abstract

The formation of relief in mountains comes from the complex interact between tectonic forcing of the lithosphere (tectonics which drives rocks motion), and atmospheric processes (climate), that affect erosion, which in turn removes material inhomogeneously from a mountain belt. Landscape is at the interface, and relief (i.e. topography) evolves depending on the conditions of climate, tectonics, and erosion. In this project I continue to work on the importance of the relative contribution of the tectonic and the erosive component to create relief. During the Plio-Quaternary, the climate became progressively colder and potentially more erosive, with glaciers periodically covering large parts of the northern hemisphere high-latitude/high-altitude areas. The effects of these climate changes on mountain building have been studied in detail using sedimentology, low-temperature thermochronology, surface exposure history, as well as numerical and physical modelling. However, because glacial erosion processes are less well understood than fluvial erosion processes, the role and importance of glacial erosion in shaping landscapes and in changing relief is disputed. Specifically, the onset, the timing and the importance of glacial valley carving is still poorly known.The present project is a follow-up of an Ambizione project that has been funded for 3 years in 2009, and focuses on two natural laboratories that present extreme topography, with different precipitation and glaciers that shape the landscape. They are 1) the St Elias Range in Alaska, where tectonic forcing is high, with a high erosion rate affected by fast-moving temperate glaciers, and 2) the Western and Central Alps, where tectonic forcing is slow, with a moderate glacier cover today, but was almost complete during glacial advances. These areas also show contrasting precipitation gradients, with a spatial variation up to a factor of 20 in the St Elias Range, and only threefold in the Alps. To achieve this study, I rely on three independent methods, that all aim to derive a complete history of relief formation and glacial valley carving in response to climatic and tectonic changes: 1) Terrestrial Cosmogenic Nuclide (TCN) concentrations in rock and sediments to document the time necessary to erode the upper ~2 meter of rock. In-situ and watershed-averaged erosion rates will be quantified, over typical timescales of 500 yrs to 5 kyrs. Many (i.e. ~60) samples have been collected and are currently under different stages of physical-chemical processing. 2) A new very-low thermochronometer based on Optically Stimulated Luminescence (OSL), with an exceptionally low closure temperature (30°C - 40°C) has been used to document the latest cooling event, in the upper ~1km of crust, and therefore quantifies valley carving and relief evolution over typical a timescale of 50 kyrs to 500 kyrs. We already have 3 vertical profiles (16 dated samples) and we are working continuously to improve the method and date more samples (20 more currently under analysis, 40 samples waiting for preliminary processing).3) Numerical modelling of fluvioglacial landscape evolution, parameterized with existing and acquired data, will document the erosion behaviour of studied ranges under variable external and internal forcing. Numerical models provided a quantitative and self-consistent scenario for Quaternary relief development and the role of glaciations, and showed that glacial erosion is bimodal, and lead to dramatic relief increase at valley-scale. A comprehensive compilation of paleoclimate and paleotopography will feed a realistic field-based numerical model of glacial erosion that is providing the evolution of the topography and the glacial erosion of the Valais area (Swiss Alps), hence gives an age of the present topography.
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