Alps; Quaternary climate; Alaska; Glacial Erosion; Tectonics; Valley formation ; Relief
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.
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.
Vouillamoz Naomi, Sue Christian, Champagnac Jean Daniel, Calcagno Philippe (2012), 3D cartographic modeling of the Alpine arc, in Tectonophysics
, 579, 131-143.
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.
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.
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.
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
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.