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MaCoMaOc: Convection in planetary mantles interactingwith magma oceans

English title MaCoMaOc: Convection in planetary mantles interactingwith magma oceans
Applicant Tackley Paul
Number 164337
Funding scheme Project funding
Research institution Institut für Geophysik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geology
Start/End 01.11.2016 - 31.10.2020
Approved amount 271'053.00
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Keywords (3)

mantle convection; magma ocean; thermal evolution

Lay Summary (French)

Lead
La formation du système Terre-Lune a produit une Terre en grand partie fondue. En particulier, le manteau silicaté, actuellement solide, a sans doute été largement liquide. La cristallisation de l'océan de magma vers le haut s'est produite en quelques dizaines de millions d'années et a pu laisser un océan de magma à la base du manteau, sous la partie solide. La convection dans la partie solide du manteau, aujourd'hui à l'origine de la tectonique des plaques, a dû être très affectée à ses débuts par la présence d'océans de magma au dessus et/ou en dessous. En particulier, un mouvement vertical n'est pas forcément arrêté par les limites horizontales dans ce cas, la fusion permettant une vitesse verticale non-nulle aux bords. L'objectif de ce projet est d'étudier les conséquences de l'existence d'océans de magma sur la dynamique convective du manteau solide et son évolution à long terme, de ses débuts à nos jours.
Lay summary

La formation du système Terre-Lune a produit une Terre en grand partie fondue. En particulier, le manteau silicaté, actuellement solide, a sans doute été largement liquide. La transition de cette phase dîte d'océan de magma à la situation dans laquelle la Terre se trouve actuellement est encore mal comprise. La cristallisation de l'océan de magma vers le haut s'est produite en quelques dizaines de millions d'années et a pu laisser un océan de magma à la base du manteau, sous la partie solide. La convection dans la partie solide du manteau, aujourd'hui à l'origine de la tectonique des plaques, a dû être très affectée à ses débuts par la présence d'océans de magma au dessus et/ou en dessous. En particulier, un mouvement vertical n'est pas forcément arrêté par les limites horizontales dans ce cas, la fusion permettant une vitesse verticale non-nulle aux bords. L'objectif de ce projet est d'étudier les conséquences de l'existence d'océans de magma sur la dynamique convective du manteau solide et son évolution à long terme, de ses débuts à nos jours.

 Quelques questions qui nous intéressent sont : quelles sont les conditions du démarrage de la convection dans le manteau solide ? Quelle est l'efficacité du transfert thermique et chimique par la convection du manteau ? L'existence d'un océan de magma basal permet-elle de résoudre le problème de l'évolution thermique de la Terre ? La structure du manteau vue par la sismologie peut-elle être expliquée par la cristallisation fractionnée d'un océan de magma basal ?

 

Direct link to Lay Summary Last update: 15.02.2016

Responsible applicant and co-applicants

Employees

Publications

Publication
Timescales of chemical equilibrium between the convecting solid mantle and over-/underlying magma oceans
Paz BolrãoDaniela, Timescales of chemical equilibrium between the convecting solid mantle and over-/underlying magma oceans, in Solid Earth, se-2020-49.

Collaboration

Group / person Country
Types of collaboration
Prof. Labrosse, Université de Lyon France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
European Geosciences Union General Assembly 2020 Poster From a magma ocean to a solid mantle: implications for the thermo-chemical evolution of Mars 04.05.2020 Vienna, Austria Tackley Paul; Labrosse Stéphane; da Paz Bolrão Daniela Sofia;
American Geophysical Union Fall Meeting 2019 Poster Impacts of gloabal magma oceans on the thermal and compositional evolution of the Earth mantle 09.12.2019 San Francisco, United States of America Labrosse Stéphane; Tackley Paul; da Paz Bolrão Daniela Sofia;
American Geophysical Union Fall Meeting 2019 Poster Reactive freezing of the basal magma ocean on Earth and other terrestrial planets 09.12.2019 San Francisco, United States of America Tackley Paul; da Paz Bolrão Daniela Sofia;
American Geophysical Union Fall Meeting 2019 Talk given at a conference Geodynamical and geochemical implications of a long lasting basal magma ocean 09.12.2019 San Francisco, United States of America Tackley Paul; da Paz Bolrão Daniela Sofia; Labrosse Stéphane;
American Geophysical Union Fall Meeting 2019 Poster Reactive freezing of the basal magma ocean on Earth and other terrestrial planets 09.12.2019 San Francisco, United States of America da Paz Bolrão Daniela Sofia;
Earth and Planetary Science Congress 2019 Talk given at a conference Numerical simulations of the thermo-chemical evolution of the solid mantle bounded by magma oceans 15.09.2019 Geneva, Switzerland Labrosse Stéphane; Tackley Paul; da Paz Bolrão Daniela Sofia;
Goldschmidt Conference 2019 Poster Thermo-compositional evolution of solid mantle in contact with magma oceans: Study with a phase change boundary condition 18.08.2019 Barcelona, Spain da Paz Bolrão Daniela Sofia; Tackley Paul; Labrosse Stéphane;
European Geosciences Union General Assembly 2019 Poster From magma oceans to solid mantle: insights from numerical simulations using a phase change boundary condition 07.04.2019 Vienna, Austria da Paz Bolrão Daniela Sofia; Tackley Paul; Labrosse Stéphane;
American Geophysical Union Fall Meeting 2018 Poster Dynamics and evolution of the primitive mantle with magma oceans 10.12.2018 Washington D.C., United States of America da Paz Bolrão Daniela Sofia; Tackley Paul; Labrosse Stéphane;
American Geophysical Union Fall Meeting 2018 Talk given at a conference From magma oceans to solid mantle: insights from numerical simulations 10.12.2018 Washington D.C., United States of America da Paz Bolrão Daniela Sofia; Labrosse Stéphane; Tackley Paul;
American Geophysical Union Fall Meeting 2018 Poster Thermo-compositional evolution of solid mantle bounded by magma oceans: insight from numerical simulations using a phase change boundary condition 10.12.2018 Washington D.C., United States of America da Paz Bolrão Daniela Sofia; Labrosse Stéphane; Tackley Paul;
European Geosciences Union General Assembly 2018 Poster Numerical simulations of the thermo-compositional evolution of the solid mantle bounded by magma oceans, (poster) 08.04.2018 Vienna, Austria Labrosse Stéphane; Tackley Paul; da Paz Bolrão Daniela Sofia;
American Geophysical Union Fall Meeting 2017 Poster Numerical simulations of melting-crystallisation processes at the boundaries between magma oceans and solid mantle 11.12.2017 New Orleans, United States of America Labrosse Stéphane; Tackley Paul; da Paz Bolrão Daniela Sofia;
Compressible Convection Conference Talk given at a conference Numerical simulations of melting-crystallisation processes at the boundaries between magma oceans and solid mantle 18.09.2017 Lyon, France Tackley Paul; Labrosse Stéphane; da Paz Bolrão Daniela Sofia;
Nethermod: XV International Workshop on Modelling of Mantle and Lithosphere Dynamics Poster Numerical simulations of melting-crystallisation processes at the boundaries between magma oceans and solid mantle 27.08.2017 Putten, Netherlands Labrosse Stéphane; da Paz Bolrão Daniela Sofia; Tackley Paul;
European Geosciences Union General Assembly 2017 Poster Solid-liquid phase changes at the boundaries between magma oceans and solid mantle: implications for mantle dynamics 23.04.2017 Vienna, Austria da Paz Bolrão Daniela Sofia; Tackley Paul; Labrosse Stéphane;
Core-Mantle Coevolution Winter School Poster Solid-liquid phase changes at the boundaries between magma oceans and solid mantle: implications for mantle dynamics 09.01.2017 Kusatsu, Japan Tackley Paul; Labrosse Stéphane; da Paz Bolrão Daniela Sofia;


Awards

Title Year
Outstanding Student Presentation Award, AGU Fall Meeting 2017 2017

Abstract

It is generally thought that in its earliest times the Earth was largely molten, owing to the enormous energy associated with its formation. On the basis of lunar observations, it has been proposed that the upper few hundreds of km of the mantle were initially liquid, forming what is commonly called a magma ocean. More recently, we proposed that a dense magma ocean could have existed at the bottom of the mantle (the basal magma ocean) and that the remnants of its slow crystallization could be observed a the present time in the form of the seismically detected ultra low velocity zones. The solid mantle is then formed from the crystallization of the magma oceans, upwards and downwards. Convection in the solid mantle is then the engine responsible for plate tectonics, while the mechanisms that allowed the transition from the dynamics in the magma ocean to that in the solid mantle are still largely unknown.This project aims at studying the effect of being bounded above and/or below by magma oceans on the dynamics of the solid mantle. The possibility of a solid/liquid phase change at the horizontal boundaries of the mantle changes the boundary conditions felt by the flow in the solid: whereas in classical con- vection problems a non-penetrating condition is generally applied (zero vertical velocity on the horizontal boundaries), which is based on the assumption that the vertical motion associated with mountain building is negligible compared to the horizontal motion of plates, the possibility of a vertical flow towards the surface melting as it gets to the molten region can effectively suppress the “braking” effect of the horizontal bound- ary. This effect has been studied in the context of the dynamics of the Earth’s inner core and we now plan to apply the same boundary conditions to the case of the mantle interacting with magma oceans. Preliminary studies that we have performed show that several effects are to be expected: the horizontal wavelength is widened, velocities and heat transfer are larger, and the onset of convection is facilitated. We will study these effects in a systematic manner as function of the main parameters: the Rayleigh number Ra (measuring the vigor of convection), internal heating rate H, rheology, geometry (spherical versus cartesian, aspect ratio), variations of density of chemical origin, and the parameters controlling the type of boundary conditions. Using several dynamical models taking into accounts these effects, we will specifically study the first over- turn of the crystallizing mantle during its crystallization, the onset of solid state thermal convection, and the developed regimes and their heat transfer characteristics. These results will allow us to address important questions on the dynamics of the early Earth and the different possible mantle convection regimes across geologic ages.The development of scaling laws for the thermal structure and heat transfer as function of the control parameters will allow us to construct a parameterized model for the coupled evolution of the core, the basal magma ocean and the mantle. This model will have the potential to solve the decades old problem of the thermal evolution of the Earth with a moderate evolution of the mantle and a large core cooling. Finally, we will build a model coupling the full dynamics of the solid mantle with moving boundaries to the core and the basal magma ocean in order to study the long term evolution of mantle dynamics, the formation of dense thermo-chemical piles at the base of the solid mantle by fractional crystallization of the basal magma ocean.
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