Solid-state mantle convection coupled with a crystallising basal magma ocean
Fractional crystallisation of a basal magma ocean (BMO) has been proposed to explain the formation of large scale compositional variations in the mantle and the persistence of partially molten patches in the lowermost mantle. We present a complete set of equations for the thermal and compositional e...
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Académie des sciences
2024-11-01
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| Series: | Comptes Rendus. Géoscience |
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| Online Access: | https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.275/ |
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| author | Labrosse, Stéphane Morison, Adrien Tackley, Paul James |
| author_facet | Labrosse, Stéphane Morison, Adrien Tackley, Paul James |
| author_sort | Labrosse, Stéphane |
| collection | DOAJ |
| description | Fractional crystallisation of a basal magma ocean (BMO) has been proposed to explain the formation of large scale compositional variations in the mantle and the persistence of partially molten patches in the lowermost mantle. We present a complete set of equations for the thermal and compositional evolution of the BMO and show that it can be implemented in a mantle convection code to solve the long term mantle evolution problem. The presence of the BMO modifies the dynamics of the mantle in several ways. The phase equilibrium at the bottom of the solid mantle implies a change of mechanical boundary condition, which helps solid state convection. The net freezing of the BMO implies a change of computational domain, which is treated by mapping the radial coordinate on a constant thickness domain. Fractional melting and freezing at the boundary makes the composition of the BMO and the solid mantle evolve, which is treated using Lagrangian tracers. A sample calculation shows that the persistence of the BMO and its long term evolution drastically changes the dynamics of the solid mantle by promoting downwelling currents and large scale flow. The gradual increase of the FeO content in the BMO and in the solid that crystallises from it leads to the stabilisation of large scale thermo-compositional piles at the bottom of the mantle, possibly explaining the observations from seismology. |
| format | Article |
| id | doaj-art-1aace429ff534cec827613535e1dd8e5 |
| institution | Kabale University |
| issn | 1778-7025 |
| language | English |
| publishDate | 2024-11-01 |
| publisher | Académie des sciences |
| record_format | Article |
| series | Comptes Rendus. Géoscience |
| spelling | doaj-art-1aace429ff534cec827613535e1dd8e52025-02-07T10:41:28ZengAcadémie des sciencesComptes Rendus. Géoscience1778-70252024-11-01356S152110.5802/crgeos.27510.5802/crgeos.275Solid-state mantle convection coupled with a crystallising basal magma oceanLabrosse, Stéphane0https://orcid.org/0000-0002-7620-4363Morison, Adrien1https://orcid.org/0000-0002-8261-9143Tackley, Paul James2https://orcid.org/0000-0003-4878-621XLGLTPE, ENS de Lyon, Université de Lyon, 46 allée d’Italie, 69003 Lyon, FranceUniv Exeter, Phys & Astron, Exeter, Devon, EnglandDepartment of Earth and Planetary Sciences, ETH Zürich, Sonneggstrasse 5, Zürich, 8092, SwitzerlandFractional crystallisation of a basal magma ocean (BMO) has been proposed to explain the formation of large scale compositional variations in the mantle and the persistence of partially molten patches in the lowermost mantle. We present a complete set of equations for the thermal and compositional evolution of the BMO and show that it can be implemented in a mantle convection code to solve the long term mantle evolution problem. The presence of the BMO modifies the dynamics of the mantle in several ways. The phase equilibrium at the bottom of the solid mantle implies a change of mechanical boundary condition, which helps solid state convection. The net freezing of the BMO implies a change of computational domain, which is treated by mapping the radial coordinate on a constant thickness domain. Fractional melting and freezing at the boundary makes the composition of the BMO and the solid mantle evolve, which is treated using Lagrangian tracers. A sample calculation shows that the persistence of the BMO and its long term evolution drastically changes the dynamics of the solid mantle by promoting downwelling currents and large scale flow. The gradual increase of the FeO content in the BMO and in the solid that crystallises from it leads to the stabilisation of large scale thermo-compositional piles at the bottom of the mantle, possibly explaining the observations from seismology.https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.275/Thermal evolutionMantle convectionCore coolingBasal magma ocean |
| spellingShingle | Labrosse, Stéphane Morison, Adrien Tackley, Paul James Solid-state mantle convection coupled with a crystallising basal magma ocean Comptes Rendus. Géoscience Thermal evolution Mantle convection Core cooling Basal magma ocean |
| title | Solid-state mantle convection coupled with a crystallising basal magma ocean |
| title_full | Solid-state mantle convection coupled with a crystallising basal magma ocean |
| title_fullStr | Solid-state mantle convection coupled with a crystallising basal magma ocean |
| title_full_unstemmed | Solid-state mantle convection coupled with a crystallising basal magma ocean |
| title_short | Solid-state mantle convection coupled with a crystallising basal magma ocean |
| title_sort | solid state mantle convection coupled with a crystallising basal magma ocean |
| topic | Thermal evolution Mantle convection Core cooling Basal magma ocean |
| url | https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.275/ |
| work_keys_str_mv | AT labrossestephane solidstatemantleconvectioncoupledwithacrystallisingbasalmagmaocean AT morisonadrien solidstatemantleconvectioncoupledwithacrystallisingbasalmagmaocean AT tackleypauljames solidstatemantleconvectioncoupledwithacrystallisingbasalmagmaocean |