Descrizione del progetto
Comprendere l’evoluzione del mantello terrestre durante la sua solidificazione
In che modo si è solidificato il primo mantello fuso della Terra per creare un pianeta attivo in termini tettonici e geomagnetici? Il progetto SEPtiM, finanziato dal CER, combinerà la petrologia sperimentale, la modellizzazione termodinamica e le simulazioni geodinamiche in maniera coerente per esaminare la cristallizzazione del mantello in laboratorio. Studierà la sequenza di cristallizzazione di colate di silicati pertinenti in laboratorio avvalendosi di un protocollo di nuova concezione nella cella a incudini di diamante riscaldata con il laser, stabilendo i rapporti di fusione e i diagrammi di fase e incorporandoli in nuovi modelli geodinamici. L’obiettivo generale del progetto consiste nella simulazione realistica dell’evoluzione dinamica e termochimica del mantello terrestre durante la sua solidificazione. I risultati aiuteranno a comprendere le prime fasi dell’evoluzione della Terra e dei pianeti.
Obiettivo
Earth’s mantle was extensively molten in its first 100 million years. Its solidification left a strong compositional and structural imprint on the mantle, still observable today in the geochemical and geophysical record. Isotopic variations in basalts and ancient crust reveal the existence of one or more mantle reservoirs that formed early in Earth’s history, and never fully remixed. Seismic tomography reveals large, chemically distinct, thermochemical structures in the lowermost mantle, anchored to the source of these anomalous basalts. These observations leave no doubt that the mantle still bears differentiated regions that preserve signatures of its solidification. However, their formation mechanisms and compositional evolution are still unknown. Unravelling those opens a new window in understanding the early stages of Earth and planetary evolution. The overarching question of this proposal: how did the primitive molten Earth solidify to form a tectonically and geomagnetically active planet? My goal is to address this question by investigating mantle crystallisation in the laboratory, by combining experimental petrology, thermodynamical modelling, and geodynamical simulations in a self-consistent fashion. I propose to assemble a multidisciplinary team to: (1) experimentally study the crystallisation sequence of relevant silicate melts in the laboratory under P-T conditions extending to those at of the depth of the core-mantle boundary, using a newly developed protocol in the laser-heated diamond anvil cell; (2) use these results to constrain a thermodynamical model of phase relations and compositions, and trace-element partitioning between solids and melts; (3) use DFT calculations to calculate the density and relative buoyancy of these solids and melts; (4) feed the thermodynamics and buoyancy as input to mushy two-phase 3D fluid dynamics simulations, to realistically simulate the dynamical and thermochemical evolution of Earth’s mantle as it solidified.
Campo scientifico
- humanitieshistory and archaeologyhistory
- natural sciencesphysical sciencesthermodynamics
- natural sciencesphysical sciencesclassical mechanicsfluid mechanicsfluid dynamics
- natural sciencesphysical sciencesastronomyplanetary sciencesplanets
- natural sciencesearth and related environmental sciencesgeologypetrology
Parole chiave
Programma(i)
Argomento(i)
Meccanismo di finanziamento
ERC-ADG - Advanced GrantIstituzione ospitante
75794 Paris
Francia