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Onset of solid-state mantle convection and mixing during magma ocean solidification

Maurice, Maxime and Tosi, Nicola and Plesa, Ana-Catalina and Samuel, Henri and Breuer, Doris and Hüttig, Christian (2016) Onset of solid-state mantle convection and mixing during magma ocean solidification. Workshop on the origins of plate tectonics, 18-22 Jul 2016, Locarno, Switzerland.

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Energy sources involved in the early stages of planetary formation can cause partial or even complete melting of the mantle of terrestrial bodies leading to the formation of magma oceans. Upon planetary cooling, solidification is expected to take place from the bottom upwards because of the steeper slope of the liquid adiabat with respect to the liquidus (Elkins-Tanton, 2012; Solomatov, 2015). Fractional solidification, in particular, can lead to the formation of a compositional layering that can play a fundamental role for the subsequent long-term dynamics and evolution of the interior (Tosi et al., 2013; Plesa et al., 2014). In order to assess to what extent primordial compositional heterogeneities generated upon magma ocean solidification can be preserved, we investigate the cooling and solidification of a whole-mantle magma ocean along with the conditions that allow solid-state convection to start mixing the mantle before solidification has completed. To this end, we run 2-D numerical simulations in cylindrical geometry using the finite-volume code GAIA (Hüttig et al., 2013). We treat the liquid magma ocean in a parametrized fashion while we self-consistently solve the conservation equations of thermochemical convection in the growing solid mantle accounting for pressure-, temperature- and melt-dependent rheology. We consider two end-member cases: fractional crystallization, where melt is instantaneously extracted into the overlying liquid leaving beneath a differentiated mantle, and batch crystallization where melt remains in contact with the silicate matrix throughout solidification causing no differentiation. By testing the effects of different cooling rates and Rayleigh numbers, we show that for a lifetime of the liquid magma ocean between 1 and 10 Myr (Lebrun et al., 2013), the onset of solid state convection prior to complete mantle crystallization is possible and that part or even all of the compositional heterogeneities generated upon fractionation can be erased by efficient mantle stirring (Figure 1). We discuss the consequences of our findings in relation to the early and long-term evolution of compositional heterogeneities generated via fractional crystallization of magma oceans in terrestrial bodies with emphasis on Mars' thermochemical history.

Item URL in elib:https://elib.dlr.de/108507/
Document Type:Conference or Workshop Item (Poster)
Title:Onset of solid-state mantle convection and mixing during magma ocean solidification
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Maurice, Maximemaxime.maurice (at) dlr.dehttps://orcid.org/0000-0001-8804-120X
Tosi, Nicolanicola.tosi (at) dlr.deUNSPECIFIED
Plesa, Ana-CatalinaAna.Plesa (at) dlr.deUNSPECIFIED
Breuer, DorisDoris.Breuer (at) dlr.deUNSPECIFIED
Hüttig, ChristianChristian.Huettig (at) dlr.deUNSPECIFIED
Date:July 2016
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:Magma ocean, Fractional crystallization, Mars, Terrestrial planets, Mantle convection, Mixing
Event Title:Workshop on the origins of plate tectonics
Event Location:Locarno, Switzerland
Event Type:Workshop
Event Dates:18-22 Jul 2016
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):R - Vorhaben Planetary Evolution and Life
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Physics
Deposited By: Maurice, Maxime
Deposited On:29 Nov 2016 11:33
Last Modified:31 Jul 2019 20:05

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