Description du projet
Cartographier les transitions du manteau profond
Le manteau inférieur est la couche interne liquide de la Terre, comprise entre 670 et 2 900 km de profondeur. La tomographie sismique a permis d’établir une cartographie tridimensionnelle du manteau inférieur. Cependant, l’interprétation des modèles visant à mettre en évidence des facteurs tels que l’hétérogénéité géochimique ou le flux dynamique du manteau a été mitigée et ambiguë. Le projet DEEP-MAPS, financé par l’UE, propose ce que ses créateurs appellent une nouvelle catégorie d’expériences à résolution temporelle qui permettront de cartographier les transitions de phase du manteau inférieur, leur impact sur les propriétés physiques et leur signature sismique. En outre, DEEP-MAPS examinera la dépendance temporelle de chaque transition de phase, contribuant ainsi à une meilleure mise à l’échelle des processus géologiques.
Objectif
Processes in Earth's lower mantle govern our planet's inner dynamics and control surface plate tectonics. As such, a quantitative understanding of the physical and chemical properties of the lower mantle is pivotal to model Earth’s dynamic evolution, including the long-term chemical interactions between mantle and atmosphere that are vital to the development of habitability on Earth, and possibly other planets. While seismic tomography is providing increasingly detailed three-dimensional maps of the lower mantle, the interpretation of tomographic models to elucidate key factors such as mantle geochemical heterogeneity or dynamic mantle flow processes has proven to be highly ambiguous.
All evidence points to phase transitions being the missing link needed to converge to a consistent interpretation of seismic observations. The same phase transitions also play a key role in governing mantle dynamics. But even fundamental properties, such as the location of major phase transition boundaries in Earth’s mantle, are poorly constrained. This is because the parameter space (pressure-temperature-composition) is huge and experimental measurements at planetary interior conditions are extremely slow.
DEEP-MAPS will employ a novel class of time-resolved high-pressure/-temperature experiments that reduce by several orders of magnitude the time for key experiments. This will allow DEEP-MAPS to map lower mantle phase transitions, their impact on physical properties and their seismic signature with practically continuous coverage in relevant pressure-temperature-composition-space. DEEP-MAPS will further probe the time-dependence of phase transitions, transforming our understanding of how to scale from laboratory measurements to geophysical processes.
DEEP-MAPS will provide a step-change in our ability to interpret mantle seismic observables and to quantify the geodynamic impact of mantle phase transitions, ultimately leading to a holistic picture of Earth’s deep mantle.
Champ scientifique
Mots‑clés
Programme(s)
Régime de financement
ERC-COG - Consolidator GrantInstitution d’accueil
OX1 2JD Oxford
Royaume-Uni