Overturn of ilmenite‐bearing cumulates in a rheologically weak lunar mantle

dc.contributor.authorYu, Shuoran
dc.contributor.authorTosi, Nicola
dc.contributor.authorSchwinger, Sabrina
dc.contributor.authorMaurice, Maxime
dc.contributor.authorBreuer, Doris
dc.contributor.authorXiao, Long
dc.date.accessioned2020-01-27T12:37:07Z
dc.date.available2020-01-27T12:37:07Z
dc.date.issued2019-01-31
dc.description©2019. American Geophysical Unionen
dc.description.abstractThe crystallization of the lunar magma ocean (LMO) determines the initial structure of the solid Moon. Near the end of the LMO crystallization, ilmenite‐bearing cumulates (IBC) form beneath the plagioclase crust. Being denser than the underlying mantle, IBC are prone to overturn, a hypothesis that explains several aspects of the Moon's evolution. Yet the formation of stagnant lid due to the temperature dependence of viscosity can easily prevent IBC from sinking. To infer the rheological conditions allowing IBC to sink, we calculated the LMO crystallization sequence and performed high‐resolution numerical simulations of the overturn dynamics. We assumed a diffusion creep rheology and tested the effects of reference viscosity, activation energy, and compositional viscosity contrast between IBC and mantle. The overturn strongly depends on reference viscosity and activation energy and is facilitated by a low IBC viscosity. For a reference viscosity of 1021 Pa s, characteristic of a dry rheology, IBC overturn cannot take place. For a reference viscosity of 1020 Pa s, the overturn is possible if the activation energy is a factor of 2–3 lower than the values typically assumed for dry olivine. These low activation energies suggest a role for dislocation creep. For lower‐reference viscosities associated with the presence of water or trapped melt, more than 95% IBC can sink regardless of the activation energy. Scaling laws for Rayleigh‐Taylor instability confirmed these results but also showed the need of numerical simulations to accurately quantify the overturn dynamics. Whenever IBC sink, the overturn occurs via small‐scale diapirs.en
dc.identifier.eissn2169-9100
dc.identifier.issn2169-9097
dc.identifier.urihttps://depositonce.tu-berlin.de/handle/11303/10636
dc.identifier.urihttp://dx.doi.org/10.14279/depositonce-9563
dc.language.isoenen
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.ddc550 Geowissenschaftende
dc.subject.otherMoonen
dc.subject.othermagma oceanen
dc.subject.otheroverturnen
dc.subject.othermantle rheologyen
dc.titleOverturn of ilmenite‐bearing cumulates in a rheologically weak lunar mantleen
dc.typeArticleen
dc.type.versionpublishedVersionen
dcterms.bibliographicCitation.doi10.1029/2018JE005739en
dcterms.bibliographicCitation.issue2en
dcterms.bibliographicCitation.journaltitleJournal of Geophysical Research: Planetsen
dcterms.bibliographicCitation.originalpublishernameWiley ; American Geophysical Union (AGU)en
dcterms.bibliographicCitation.originalpublisherplaceHoboken, NJen
dcterms.bibliographicCitation.pageend436en
dcterms.bibliographicCitation.pagestart418en
dcterms.bibliographicCitation.volume124en
tub.accessrights.dnbfreeen
tub.affiliationFak. 2 Mathematik und Naturwissenschaften::Zentrum für Astronomie und Astrophysikde
tub.affiliation.facultyFak. 2 Mathematik und Naturwissenschaftende
tub.affiliation.instituteZentrum für Astronomie und Astrophysikde
tub.publisher.universityorinstitutionTechnische Universität Berlinen

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