dc.contributor.author
Sikdar, Jinia
dc.contributor.author
Becker, Harry
dc.contributor.author
Schuessler, Jan A.
dc.date.accessioned
2023-07-18T12:49:15Z
dc.date.available
2023-07-18T12:49:15Z
dc.identifier.uri
https://refubium.fu-berlin.de/handle/fub188/39927
dc.identifier.uri
http://dx.doi.org/10.17169/refubium-39649
dc.description.abstract
Silicon and iron isotope compositions of different physically separated components of enstatite chondrites (EC) were determined in this study to understand the role of nebular and planetary scale events in fractionating Si and Fe isotopes of the terrestrial planet-forming region. We found that the metal–sulfide nodules of EC are strongly enriched in light Si isotopes (δ30Si ≥ −5.61 ± 0.12‰, 2SD), whereas the δ30Si values of angular metal grains, magnetic, slightly magnetic, and non-magnetic fractions become progressively heavier, correlating with their Mg# (Mg/(Mg+Fe)). White mineral phases, composed primarily of SiO2 polymorphs, display the heaviest δ30Si of up to +0.23 ± 0.10‰. The data indicate a key role of metal–silicate partitioning on the Si isotope composition of EC. The overall lighter δ30Si of bulk EC compared to other planetary materials can be explained by the enrichment of light Si isotopes in EC metals along with the loss of isotopically heavier forsterite-rich silicates from the EC-forming region. In contrast to the large Si isotope heterogeneity, the average Fe isotope composition (δ56Fe) of EC components was found to vary from −0.30 ± 0.08‰ to +0.20 ± 0.04‰. A positive correlation between δ56Fe and Ni/S in the components suggests that the metals are enriched in heavy Fe isotopes whereas sulfides are the principal hosts of light Fe isotopes in the non-magnetic fractions of EC. Our combined Si and Fe isotope data in different EC components reflect an inverse correlation between δ30Si and δ56Fe, which illustrates that partitioning of Si and Fe among metal, silicate, and sulfidic phases has significantly fractionated Si and Fe isotopes under reduced conditions. Such isotope partitioning must have occurred before the diverse components were mixed to form the EC parent body. Evaluation of diffusion coefficients of Si and Fe in the metal and non-metallic phases suggests that the Si isotope compositions of the silicate fractions of EC largely preserve information of their nebular processing. On the other hand, the Fe isotopes might have undergone partial or complete re-equilibration during parent body metamorphism. The relatively uniform δ56Fe among different types of bulk chondrites and the Earth, despite Fe isotope differences among their components, demonstrates that the chondrite parent bodies were not formed by random mixing of chondritic components from different locations in the disk. Instead, the chondrite components mostly originated in the same nebular reservoir and Si and Fe isotopes were fractionated either due to gas–solid interactions and associated changes in physicochemical environment of the nebular reservoir and/or during parent body processing. The heavier Si isotope composition of the bulk silicate Earth may require accretion of chondritic and/or isotopically heavier EC silicates along with cumulation of refractory forsterite-rich heavier silicates lost from the EC-forming region to form the silicate reservoir of the Earth.
en
dc.format.extent
24 Seiten
dc.rights.uri
https://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subject
enstatite chondrites
en
dc.subject
silicon isotopes
en
dc.subject
iron isotopes
en
dc.subject.ddc
500 Naturwissenschaften und Mathematik::550 Geowissenschaften, Geologie::550 Geowissenschaften
dc.title
Silicon and iron isotopes in components of enstatite chondrites: Implications for metal–silicate–sulfide fractionation in the solar nebula
dc.type
Wissenschaftlicher Artikel
dcterms.bibliographicCitation.doi
10.1111/maps.13990
dcterms.bibliographicCitation.journaltitle
Meteoritics & Planetary Science
dcterms.bibliographicCitation.number
7
dcterms.bibliographicCitation.pagestart
978
dcterms.bibliographicCitation.pageend
1001
dcterms.bibliographicCitation.volume
58
dcterms.bibliographicCitation.url
https://doi.org/10.1111/maps.13990
refubium.affiliation
Geowissenschaften
refubium.affiliation.other
Institut für Geologische Wissenschaften / Fachrichtung Geochemie, Hydrogeologie, Mineralogie
refubium.funding
DEAL Wiley
refubium.note.author
Die Publikation wurde aus Open Access Publikationsgeldern der Freien Universität Berlin gefördert.
refubium.resourceType.isindependentpub
no
dcterms.accessRights.openaire
open access
dcterms.isPartOf.eissn
1945-5100