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dc.contributor.authorFagan, T. J.
dc.contributor.authorTaylor, G. J.
dc.contributor.authorKeil, K.
dc.contributor.authorHicks, T. L.
dc.contributor.authorKillgore, M.
dc.contributor.authorBunch, T. E.
dc.contributor.authorWittke, J. H.
dc.contributor.authorMittlefehldt, D. W.
dc.contributor.authorClayton, R. N.
dc.contributor.authorMayeda, T. K.
dc.contributor.authorEugster, O.
dc.contributor.authorLorenzetti, S.
dc.contributor.authorNorman, M. D.
dc.date.accessioned2021-02-12T20:56:07Z
dc.date.available2021-02-12T20:56:07Z
dc.date.issued2003-01-01
dc.identifier.citationFagan, T. J., Taylor, G. J., Keil, K., Hicks, T. L., Killgore, M., Bunch, T. E., ... & Norman, M. D. (2003). Northwest Africa 773: Lunar origin and iron‐enrichment trend. Meteoritics & Planetary Science, 38(4), 529-554.
dc.identifier.issn1945-5100
dc.identifier.doi10.1111/j.1945-5100.2003.tb00025.x
dc.identifier.urihttp://hdl.handle.net/10150/655680
dc.description.abstractThe meteorite Northwest Africa 773 (NWA 773) is a lunar sample with implications for the evolution of mafic magmas on the moon. A combination of key parameters including whole-rock oxygen isotopic composition, Fe/Mn ratios in mafic silicates, noble gas concentrations, a KREEP-like rare earth element pattern, and the presence of regolith agglutinate fragments indicate a lunar origin for NWA 773. Partial maskelynitization of feldspar and occasional twinning of pyroxene are attributed to shock deformation. Terrestrial weathering has caused fracturing and precipitation of Carich carbonates and sulfates in the fractures, but lunar minerals appear fresh and unoxidized. The meteorite is composed of two distinct lithologies: a two-pyroxene olivine gabbro with cumulate texture, and a polymict, fragmental regolith breccia. The olivine gabbro is dominated by cumulate olivine with pigeonite, augite, and interstitial plagioclase feldspar. The breccia consists of several types of clasts but is dominated by clasts from the gabbro and more FeO-rich derivatives. Variations in clast mineral assemblage and pyroxene Mg/(Mg + Fe) and Ti/(Ti + Cr) record an igneous Fe-enrichment trend that culminated in crystallization of fayalite + silica + hedenbergitebearing symplectites. The Fe-enrichment trend and cumulate textures observed in NWA 773 are similar to features of terrestrial ponded lava flows and shallow-level mafic intrusives, indicating that NWA 773 may be from a layered mafic intrusion or a thick, differentiated lava flow. NWA 773 and several other mafic lunar meteorites have LREE-enriched patters distinct from Apollo and Luna mare basalts, which tend to be LREE-depleted. This is somewhat surprising in light of remote sensing data that indicates that the Apollo and Luna missions sampled a portion of the moon that was enriched in incompatible heatproducing elements.
dc.language.isoen
dc.publisherThe Meteoritical Society
dc.relation.urlhttps://meteoritical.org/
dc.rightsCopyright © The Meteoritical Society
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectmare basalts
dc.subjectMoon
dc.subjectNWA 773
dc.subjectlunar meteorites
dc.subjectCumulates
dc.titleNorthwest Africa 773: Lunar origin and iron-enrichment trend
dc.typeArticle
dc.typetext
dc.identifier.journalMeteoritics & Planetary Science
dc.description.collectioninformationThe Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.
dc.eprint.versionFinal published version
dc.description.admin-noteMigrated from OJS platform February 2021
dc.source.volume38
dc.source.issue4
dc.source.beginpage529
dc.source.endpage554
refterms.dateFOA2021-02-12T20:56:07Z


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