LINK<\/strong><\/a><\/p>\n\n\n\n“A coarse-grained igneous calcium-aluminum-rich inclusion (CAI) N-53, 4.3\u2009\u00d7\u20095.9\u2009mm in size, from the CR (Renazzo-type) carbonaceous chondrite Northwest Africa (NWA) 6043 is composed of two mineralogically, chemically, and isotopically distinct units\u2014type B (B) and type C (C). Type B unit occurs in the CAI core and consists of melilite (\u00c5k28\u201356), AlTi-diopside, anorthite, spinel, and minor Fe,Ni-metal. Type C unit forms islands in B (Cc) and mantle (Cm) around it and consists of Na-bearing \u00e5kermanitic melilite (\u00c5k58\u201372, 0.18\u20130.86\u2009wt% Na2O), anorthite, AlTi-diopside (up to 1.2\u2009wt% Cr2O3), spinel (up to 2.1\u2009wt% Cr2O3), perovskite, and minor wollastonite. The outermost portion of N-53 contains relict grains of olivine (Fa4) and low-Ca pyroxene (Fs4Wo5); Wark\u2013Lovering rim is absent. Magnesian spinel in B and C is 16O-rich (\u039417O\u2009~\u2009\u221223\u2030); Cr-bearing spinel in Cm is 16O-depleted (\u039417O\u2009~\u2009\u221211\u2030). AlTi-diopside, anorthite, and melilite in B and Cc are 16O-depleted to various degrees (\u039417O\u2009~\u2009\u221222\u2030 to \u221219\u2030, \u221221\u2030 to \u221217\u2030, \u221213\u2030 to \u22128\u2030, respectively). AlTi-diopside, anorthite, and melilite in Cm show a range of compositions correlated with a distance from the CAI edge (\u039417O\u2009~\u2009\u221218\u2030 to \u22128\u2030, \u221216\u2030 to \u22128\u2030, ~ \u22128\u2030 to \u22122\u2030). Melilite in B has the heaviest Mg-isotope composition (\u039425Mg\u2009~\u200910\u2030); average \u039425Mg of melilite, AlTi-diopside, and spinel in C are ~9, ~8\u2030, and ~6\u2030, respectively; anorthite in both units has \u039425Mg of ~4\u2030. On the Al-Mg evolutionary diagram, melilite data in B oscillate around the canonical isochron. Melilite, AlTi-diopside, and spinel in C have resolvable \u03b426Mg* and deviate to the left of this isochron; anorthite in both units has barely resolvable \u03b426Mg*. Although these data are consistent with late-stage reprocessing of N-53, they provide no clear chronological information. We conclude that N-53 experienced multiple melting events. Initial melting of solid precursors took place in an 16O-rich gaseous reservoir and resulted in formation of the uniformly 16O-rich (\u039417O\u2009~\u2009\u221224\u2030) type B CAI. Subsequent single- or multi-stage partial melting of this CAI occurred in an 16O-depleted gaseous reservoir(s) and resulted in addition of SiO and Na to the CAI melt, O- and Mg-isotope exchange, and crystallization of C unit.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Kirsten Larsen, Alexander N. Krot, Daniel Wielandt, Kazuhide Nagashima, Guy Libourel, Martin Bizzarro MAPS, Version of Record online: 20 March 2025 LINK “A coarse-grained igneous calcium-aluminum-rich inclusion (CAI) N-53, 4.3\u2009\u00d7\u20095.9\u2009mm in size, from the CR…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[66,9,12,57],"tags":[1846,3273,1810,4793,1653,2502,1845,135,727,725],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/37977"}],"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=37977"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/37977\/revisions"}],"predecessor-version":[{"id":37978,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/37977\/revisions\/37978"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=37977"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=37977"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=37977"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}