Project

Discipline

erosion; numerical modeling; climate change; magma production; glaciation; sea level change; magmatism and volcanism; lithospheric strain; landscape evolution

Lead
Très étudiées, les relations entre les cycles climatiques, l’érosion et les processus profonds, contrôlent l’évolution du paysage et des couches de surface de la Terre. La compréhension du forçage mutuel entre ces facteurs dominants, y compris les interactions avec l’activité humaine, a donc des grandes implications non seulement concernant la connaissance de l’évolution passé de notre planète, mais aussi pour les prévisions des changements environnementaux futurs en réponse, par example, au réchauffement climatique mondial actuel.
Lay summary
A aujourd’hui, la recherche a porté sur les effets des changements de charge lithosphérique liés à la formation/fonte de calotte glaciaires ou aux variations du niveau de la mer sur la production, transfert et éruption de magma et CO2. Cependant, les fjords, les surcreusements glaciaires et les vallées fluviatiles incisées sont témoins des grandes variations des taux d’érosion liées aux cycles climatiques. Comment le déchargement lithosphérique par l'érosion affecte-t-il les processus magmatiques en profondeur et leur expression à la surface? Cette question est primaire car la production de magma influence la fréquence et la magnitude des éruptions volcaniques ainsi que la répartition des dépôts minières. En outre, les émissions de CO2 volcaniques contribuent à l'effet de serre, alors que le climat et l'érosion modifient le paysage dans lequel nous vivons en générant des problèmes croissants liés aux évaluations des risques (inondations, glissements de terrain, séismes, etc.) et la gestion du territoire et des ressources naturelles. Ce projet aborde cette question par le biais de la modélisation numérique appliquée à des cas naturels comportants des changements considérables de charge à la surface liés à l'érosion, mais pour lesquels un lien avec magmatisme n'a jamais été explorée. Notre travail générera des informations inédites et essentielles quant aux interactions entre changement climatiques, évolution du paysage et activité volcanique. Les résultats permettront de conseiller le monde politique afin d’améliorer le monitoring environnemental ainsi que l'exploitation des ressources naturelles et de protéger la population contre les risques environnementaux.

Direct link to Lay Summary

Last update: 06.10.2016

Active participation

Self-organised

Active participation

Communication	Title	Media	Place	Year

One of the most important recent advances in Earth Sciences has been the recognition of feedbacks between climate, erosion processes and the deep Earth geodynamics at different space and time scales. The waxing and waning of ice sheets during the late-Cenozoic and associated sea level changes, for example, modulate the loading state of the lithosphere and mantle at depth. To date, research focused on the effect of lithospheric loading/unloading by ice and sea level changes on the production, transfer and eruption of magma and CO2. However, deep fjords, glacial over-deepened valleys and the ubiquitous low-stand fluvial incisions on shelves around the world testify for intense erosion associated with sea level changes and ice building/melting. Because the density of rocks is two to three times larger than that of water and ice, even comparatively small amounts of erosion affect significantly the lithospheric unloading and it associated magmatism and CO2 production. I identify this as a fundamental research opportunity that this proposal aims to address: how does lithospheric unloading by erosion affect the magmatic processes at depth and their surface expression? This question is of primary importance because the production of magma is known to influence the frequency and magnitude of volcanic eruptions and the distribution of ore deposits. Furthermore, volcanic CO2 emissions contribute to greenhouse effects, while climate and erosion modify the landscape we live in, also rising issues related to hazard assessments (e.g., flooding, land-sliding, etc.) and management of the territory and natural resources. Thus, understanding the mutual forcing between climate, erosion and magmatism, including the interactions with human life, has great implications for our planet’s habitability and predictions of future environmental conditions in response to current global climate warming.I propose to tackle this question through forward numerical modelling applied to natural case studies in which perturbations of the surface load have been documented, but for which a link with magmatism has not been explored. The research project, in particular, will involve three main actions.1)Implementation of a current landscape evolution model with more advanced sub-glacial dynamics including sediment entrainment, transport and deposition.2)Modeling of mantle melting in response to two extreme Cenozoic unloading and magmatic events, on which existing data elicited controversies: the Paleocene-Eocene Thermal Maximum (~56 Ma) and the Messinian salinity crisis (5.97-5.33 Ma). 3)Joint application of the newly implemented landscape evolution and geodynamic models to assess the forcing on the Quaternary evolution of the Southern Andean volcanic arc dictated by latitudinal variations of climate and erosion.Existing datasets relating to spatial-temporal variations of the surface load and magmatic activity will allow for cross-calibration of the numerical setups and validation of the numerical results.This project is cut-edge and has sound basis outlined in a recent publication in collaboration with researchers from the University of Geneva and the ETH-Zürich (Sternai et al., 2016), in which we show that erosion throughout glacial-interglacial cycles is indeed able to modulate the sub-continental magma productivity. The wide implications of this finding on our understanding of the couplings between global climate change and the solid Earth call for more detailed quantifications of this recently recognized link, to which I aspire through this research proposal. The project promotes an innovative approach consisting in coupling research of the Earth’s surface and deep dynamics, which have traditionally operated distinctly. Crossing usual disciplinary boundaries ensures high visibility to the proposed research from the broad Earth Science community.