LINK<\/strong><\/a><\/p>\n\n\n\n“Palisade bodies, mineral assemblages with spinel shells, in coarse\u2010grained Ca\u2010, Al\u2010rich inclusions (CAIs) have been considered either as exotic \u201cmini\u2010CAIs\u201d captured by their host inclusions (Wark and Lovering 1982) or as in situ crystallization products of a bubble\u2010rich melt (Simon and Grossman 1997). In order to clarify their origins, we conducted a comprehensive study of palisade bodies in an Allende Type B CAI (BBA\u20107), using electron backscatter diffraction (EBSD), micro\u2010computed tomography (Micro\u2010CT), electron probe microanalysis (EPMA), and secondary ion mass spectrometry (SIMS). New observations support the in situ crystallization mechanism: early\/residual melt infiltrated into spinel\u2010shelled bubbles and crystallized inside. Evidence includes (1) continuous crystallography of anorthite from the interior of the palisade body to the surrounding host; (2) partial consolidation of two individual palisade bodies revealed by micro\u2010CT; (3) a palisade body was entirely enclosed in a large anorthite crystal, and the anorthite within the palisade body shows the same crystallographic orientation as the anorthite host; and (4) identical chemical and oxygen isotopic compositions of the constituent minerals between the palisade bodies and the surrounding host. Oxygen isotopic compositions of the major minerals in BBA\u20107 are bimodal\u2010distributed. Spinel and fassaite are uniformly 16O\u2010rich with \u220617O = \u221223.3 \u00b1 1.5\u2030 (2SD), and melilite and anorthite are homogeneously 16O\u2010poor with \u220617O = \u22123.2 \u00b1 0.7\u2030 (2SD). The latter \u220617O value overlaps with that of the Allende matrix (\u220617O ~ \u22122.87\u2030) (Clayton and Mayeda 1999), which could be explained by secondary alteration with a 16O\u2010poor fluid in the parent body. The mobility of fluid could be facilitated by the high porosity (1.56\u20132.56 vol%) and connectivity (~0.17\u20130.55 vol%) of this inclusion.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Mingming Zhang, Yangting Lin, Ingo Leya, Guoqiang Tang, Yu Liu Meteoritics & Planetary Science First Published: 21 February 2019 LINK “Palisade bodies, mineral assemblages with spinel shells, in coarse\u2010grained Ca\u2010, Al\u2010rich inclusions (CAIs) have been…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[66,9,585,14,57],"tags":[108,1846,4890,4891,135,727],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/17776"}],"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=17776"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/17776\/revisions"}],"predecessor-version":[{"id":17777,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/17776\/revisions\/17777"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=17776"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=17776"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=17776"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}