LINK<\/strong><\/a><\/p>\n“High-precision secondary ion mass spectrometry (SIMS) was employed to investigate oxygen three isotopes of phenocrysts in 35 chondrules from the Yamato (Y) 82094 ungrouped 3.2 carbonaceous chondrite. Twenty-one of 21 chondrules have multiple homogeneous pyroxene data (\u220617O 3SD analytical uncertainty: 0.7\u2030); 17 of 17 chondrules have multiple homogeneous pyroxene and plagioclase data. Twenty-one of 25 chondrules have one or more olivine data matching coexisting pyroxene data. Such homogeneous phenocrysts (1) are interpreted to have crystallized from the final chondrule melt, defining host O-isotope ratios; and (2) suggest efficient O-isotope exchange between ambient gas and chondrule melt during formation. Host values plot within 0.7\u2030 of the primitive chondrule mineral (PCM) line. Seventeen chondrules have relict olivine and\/or spinel, with some \u03b417O and \u03b418O values approaching \u221240\u2030, similar to CAI or AOA-like precursors. Regarding host chondrule data, 22 of 34 have Mg#s of 98.8\u201399.5 and \u220617O of \u22123.9\u2030 to \u22126.1\u2030, consistent with most Acfer 094, CO, CR, and CV chondrite chondrules, and suggesting a common reduced O-isotope reservoir devoid of 16O-poor H2O. Six Y-82094 chondrules have \u220617O near \u22122.5\u2030, with Mg#s of 64\u201397, consistent with lower Mg# chondrules from Acfer 094, CO, CR, and CV chondrites; their signatures suggest precursors consisting of those forming Mg# ~99, \u220617O: \u22125\u2030 \u00b1 1\u2030 chondrules plus 16O-poor H2O, at high dust enrichments. Three type II chondrules plot slightly above the PCM line, near the terrestrial fractionation line (\u220617O: ~+0.1\u2030). Their O-isotopes and olivine chemistry are like LL3 type II chondrules, suggesting they sampled ordinary chondrite-like chondrule precursors. Finally, three Mg# >99 chondrules have \u220617O of \u22126.7\u2030 to \u22128.1\u2030, potentially due to 16O-rich refractory precursor components. The predominance of Mg# ~99, \u220617O: \u22125\u2030 \u00b1 1\u2030 chondrules and a high chondrule-to-matrix ratio suggests bulk Y-82094 characteristics are closely related to anhydrous dust sampled by most carbonaceous chondrite chondrules.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Tenner, T. J., Kimura, M. and Kita, N. T. Meteoritics & Planetary Science. doi: 10.1111\/maps.12791 LINK “High-precision secondary ion mass spectrometry (SIMS) was employed to investigate oxygen three isotopes of phenocrysts in 35 chondrules from…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,56,65,335],"tags":[106,1731,527],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/10875"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10875"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/10875\/revisions"}],"predecessor-version":[{"id":10876,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/10875\/revisions\/10876"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10875"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10875"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10875"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}