LINK<\/strong><\/a><\/p>\n\n\n\n“We performed in situ oxygen three\u2010isotope measurements of chondrule olivine, pyroxenes, and plagioclase from the newly described CVRed chondrite NWA 8613. Additionally, oxygen isotope ratios of plagioclase in chondrules from the Kaba CV3OxB chondrite were determined to enable comparisons of isotope ratios and degree of alteration of chondrules in both CV lithologies. NWA 8613 was affected by only mild thermal metamorphism. The majority of oxygen isotope ratios of olivine and pyroxenes plot along a slope\u20101 line in the oxygen three\u2010isotope diagram, except for a type II and a remolten barred olivine chondrule. When isotopic relict olivine is excluded, olivine, and low\u2010 and high\u2010Ca pyroxenes are indistinguishable regarding \u039417O values. Conversely, plagioclase in chondrules from NWA 8613 and Kaba plot along mass\u2010dependent fractionation lines. Oxygen isotopic disequilibrium between phenocrysts and plagioclase was caused probably by exchange of plagioclase with 16O\u2010poor fluids on the CV parent body. Based on an existing oxygen isotope mass balance model, possible dust enrichment and ice enhancement factors were estimated. Type I chondrules from NWA 8613 possibly formed at moderately high dust enrichment factors (50\u00d7 to 150\u00d7 CI dust relative to solar abundances); estimates for water ice in the chondrule precursors range from 0.2\u00d7 to 0.6\u00d7 the nominal amount of ice in dust of CI composition. Findings agree with results from an earlier study on oxygen isotopes in chondrules of the Kaba CV chondrite, providing further evidence for a relatively dry and only moderately high dust\u2010enriched disk in the CV chondrule\u2010forming region.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Andreas T. Hertwig, Makoto Kimura, C\u00e9line Defouilloy, Noriko T. Kita Meteoritics & Planetary Science First Published: 30 August 2019 LINK “We performed in situ oxygen three\u2010isotope measurements of chondrule olivine, pyroxenes, and plagioclase from the…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,148,14,22,65],"tags":[3273,1864,1812,3636,1636,5161,1845],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20349"}],"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=20349"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20349\/revisions"}],"predecessor-version":[{"id":20350,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20349\/revisions\/20350"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=20349"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=20349"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=20349"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}