Age, genetics, and crystallization sequence of the group IIIE iron meteorites

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dc.contributor.authorChiappe, Emily M.
dc.contributor.authorAsh, Richard
dc.contributor.authorWalker, Richard J.
dc.date.accessioned2024-05-31T18:29:36Z
dc.date.available2024-05-31T18:29:36Z
dc.date.issued2023-06-14
dc.description.abstractChemical and isotopic data were obtained for ten iron meteorites classified as members of the IIIE group. Nine of the IIIE irons exhibit broadly similar bulk siderophile element characteristics. Modeling of highly siderophile element abundances suggests that they can be related to one another through simple crystal-liquid fractionation of a parent melt. Our preferred model suggests initial S, P, and C concentrations of approximately 12 wt%, 0.8 wt %, and 0.08 wt%, respectively. The modeled IIIE parent melt composition is ~4 times more enriched in highly siderophile elements than a non-carbonaceous (NC) chondrite-like parent body, suggesting a core comprising ~22% of the mass of the parent body. Although chemically distinct from the other IIIE irons, formation of the anomalous IIIE iron Aletai can potentially be accounted for under the conditions of this model through the nonequilibrium mixing of an evolved liquid and early formed solid. Cosmic ray exposure-corrected nucleosynthetic Mo, Ru, and W isotopic compositions of four of the bona fide IIIE irons and Aletai indicate that they originated from the non-carbonaceous (NC) isotopic domain. Tungsten-182 isotopic data for the IIIE irons and Aletai yield similar model metal-silicate segregation ages of 1.6 ± 0.8 Myr and 1.2 ± 0.8 Myr, respectively, after calcium aluminum-rich inclusion (CAI) formation. These ages are consistent with those reported for other NC-type iron meteorite parent bodies. The IIIE irons are chemically and isotopically similar to the much larger IIIAB group. Despite some textural, mineralogical, and chemical differences, such as higher C content, the new results suggest they may have originated from a different crystallization sequence on the same or closely-related parent body.
dc.description.sponsorshipThis study was supported by NASA Emerging Worlds grant 80NSSC20K0335 (to RJW)
dc.description.urihttps://doi.org/10.1016/j.gca.2023.06.009
dc.identifierhttps://doi.org/10.13016/o7ws-rvqa
dc.identifier.urihttp://hdl.handle.net/1903/32581
dc.language.isoen_US
dc.publisherElsevier
dc.relation.isAvailableAtCollege of Computer, Mathematical & Natural Sciencesen_us
dc.relation.isAvailableAtGeologyen_us
dc.relation.isAvailableAtDigital Repository at the University of Marylanden_us
dc.relation.isAvailableAtUniversity of Maryland (College Park, MD)en_us
dc.rightsCC0 1.0 Universalen
dc.rights.urihttp://creativecommons.org/publicdomain/zero/1.0/
dc.subjectIIIE iron meteorites
dc.subjectHighly siderophile elements
dc.subjectFractional crystallization
dc.subjectHf-W chronometry
dc.subjectMeteorite genetics
dc.titleAge, genetics, and crystallization sequence of the group IIIE iron meteorites
dc.typeArticle
local.equitableAccessSubmissionYes

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