LINK<\/strong><\/a><\/p>\n\n\n\n“Calcium\u2010aluminum\u2010rich inclusions (CAIs) are the first solid materials formed in the solar nebula. Among them, ultrarefractory inclusions are very rare. In this study, we report on the mineralogical features and oxygen isotopic compositions of minerals in a new ultrarefractory inclusion CAI 007 from the CV3 chondrite Northwest Africa (NWA) 3118. The CAI 007 inclusion is porous and has a layered (core\u2013mantle\u2013rim) texture. The core is dominant in area and mainly consists of Y\u2010rich perovskite and Zr\u2010rich davisite, with minor refractory metal nuggets, Zr,Sc\u2010rich oxide minerals (calzirtite and tazheranite), and Fe\u2010rich spinel. The calzirtite and tazheranite are closely intergrown, probably derived from a precursor phase due to thermal metamorphism on the parent body. The refractory metal nuggets either exhibit thin exsolution lamellae of Fe,Ni\u2010dominant alloy in Os,Ir\u2010dominant alloy or are composed of Os,Ir,Ru,Fe\u2010alloy and Fe,Ni,Ir\u2010alloy with troilite, scheelite, gypsum, and molybdenite. The later four phases are apparently secondary minerals. The Zr,Sc,Y\u2010rich core is surrounded by a discontinuous layer of closely intergrown hibonite and spinel. The CAIs are rimmed by Fe\u2010rich spinel and Al\u2010rich diopside. Perovskite has high concentrations of the most refractory rare earth elements (REEs) but is relatively depleted in the moderately refractory and volatile REEs, consistent with the ultrarefractory REE pattern. Based on this unusual Zr,Sc,Y\u2010rich mineral assemblage, the layered distribution in CAI 007, and the REE concentrations in perovskite, we suggest that CAI 007 is an ultrarefractory inclusion of condensation origin. In CAI 007, hibonite, spinel, and probably Al\u2010rich diopside are 16O\u2010rich (\u039417O ~\u201322\u2030) whereas perovskite and davisite are 16O\u2010poor (\u039417O ~\u20133\u2030). Such oxygen isotope heterogeneity suggests that the UR inclusion formed in the various degrees of 16O\u2010rich nebular setting or was originally 16O\u2010rich and then experienced oxygen isotope exchange with 16O\u2010poor fluid on the CV3 chondrite parent body.”<\/p>\n","protected":false},"excerpt":{"rendered":"
Yong Xiong, Ai\u2010Cheng Zhang, Noriyuki Kawasaki, Chi Ma, Naoya Sakamoto, Jia\u2010Ni Chen, Li\u2010Xin Gu, Hisayoshi Yurimoto Meteoritics & Planetary ScienceVersion of Record online: 14 October 2020 LINK “Calcium\u2010aluminum\u2010rich inclusions (CAIs) are the first solid materials…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[66,9,14,65],"tags":[2404,1846,3273,4754,147,4373],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25132"}],"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=25132"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25132\/revisions"}],"predecessor-version":[{"id":25133,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25132\/revisions\/25133"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25132"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25132"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25132"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}