LINK<\/strong><\/a><\/p>\n“Precise triple oxygen isotope compositions of 32 Allende bulk chondrules (ABCs) are determined using laser\u2010assisted fluorination mass spectrometry. Various chemically characterized chondrule types show ranges in \u03b418O that vary from \u22124.80\u2030 to +1.10\u2030 (porphyritic olivine; PO, N = 15), \u22123.10\u2030 to +1.50\u2030 (porphyritic olivine pyroxene; POP, N = 9), \u22123.40\u2030 to +2.60\u2030 (barred olivine; BO, N = 4), and \u22123.60\u2030 to +1.30\u2030 (porphyritic pyroxene; PP, N = 3). Oxygen isotope data of these chondrules yield a regression line referred to as the Allende bulk chondrule line (ABC line, slope = 0.86 \u00b1 0.02). Most of our data fall closer to the primitive chondrule minerals line (PCM line, slope = 0.987 \u00b1 0.013) and the carbonaceous chondrite anhydrous mineral line (CCAM line, slope = 0.94 \u00b1 0.02) than the Allende anhydrous mineral line (AAML, slope = 1.00 \u00b1 0.01) with a maximum \u03b418O value (+2.60\u2030) observed in a BO chondrule and a minimum \u03b418O value (\u22124.80\u2030) shown by a PO chondrule. Similarly, these chondrules depict variable \u220617O values that range from \u22125.65\u2030 to \u22123.25\u2030 (PO), \u22124.60\u2030 to \u22122.80\u2030 (POP), \u22124.95\u2030 to \u22123.00\u2030 (BO), \u22125.30\u2030 to \u22123.20\u2030 (PP), and \u22124.90\u2030 (CC). A simple model is proposed for the Allende CV3 chondrite with reference to the AAML and PCM line to illustrate the isotopic variations occurred due to the aqueous alteration processes. The estimated temperature ranging from 10 to 130 \u00b0C (mean ~60 \u00b0C) implies that the secondary mineralization in Allende happened in a warmer and relatively dry environment compared to Murchison. We further propose that thermal metamorphism could have dehydrated the Allende matrix at temperatures between >150 \u00b0C and <600 \u00b0C. \"\n<\/p>\n","protected":false},"excerpt":{"rendered":"
Iffat Jabeen, Minoru Kusakabe, Keisuke Nagao, Arshad Ali Meteoritics & Planetary Science First Published: 30 November 2018 LINK “Precise triple oxygen isotope compositions of 32 Allende bulk chondrules (ABCs) are determined using laser\u2010assisted fluorination mass…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61,9,56,14,20,65,62],"tags":[108,1842,3273,1839,1812,2491,1843],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/16839"}],"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=16839"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/16839\/revisions"}],"predecessor-version":[{"id":16840,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/16839\/revisions\/16840"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=16839"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=16839"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=16839"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}