{"id":20724,"date":"2019-11-21T14:29:39","date_gmt":"2019-11-21T13:29:39","guid":{"rendered":"http:\/\/karmaka.de\/?p=20724"},"modified":"2019-11-21T14:46:17","modified_gmt":"2019-11-21T13:46:17","slug":"the-presolar-grain-inventory-of-fine%e2%80%90grained-chondrule-rims-in-the-mighei%e2%80%90type-cm-chondrites","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=20724","title":{"rendered":"The presolar grain inventory of fine\u2010grained chondrule rims in the Mighei\u2010type (CM) chondrites<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Jan Leitner, Knut Metzler, Christian Vollmer, Christine Floss, Pierre Haenecour, J\u00e1nos Kodol\u00e1nyi, Dennis Harries, Peter Hoppe<\/p>\n\n\n\n<p>Meteoritics &amp; Planetary Science <\/p>\n\n\n\n<p><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/full\/10.1111\/maps.13412\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br>\n<a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/epdf\/10.1111\/maps.13412\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;We investigated the inventory of presolar silicate, oxide, and silicon carbide (SiC) grains of fine\u2010grained chondrule rims in six Mighei\u2010type (CM) carbonaceous chondrites (Banten, Jbilet Winselwan, Maribo, Murchison, Murray and Yamato 791198), and the CM\u2010related carbonaceous chondrite Sutter&#8217;s Mill. Sixteen O\u2010anomalous grains (nine silicates, six oxides) were detected, corresponding to a combined matrix\u2010normalized abundance of ~18 ppm, together with 21 presolar SiC grains (~42 ppm). Twelve of the O\u2010rich grains are enriched in 17O, and could originate from low\u2010mass asymptotic giant branch stars. One grain is enriched in 17O and significantly depleted in 18O, indicative of additional cool bottom processing or hot bottom burning in its stellar parent, and three grains are of likely core\u2010collapse supernova origin showing enhanced 18O\/16O ratios relative to the solar system ratio. We find a presolar silicate\/oxide ratio of 1.5, significantly lower than the ratios typically observed for chondritic meteorites. This may indicate a higher degree of aqueous alteration in the studied meteorites, or hint at a heterogeneous distribution of presolar silicates and oxides in the solar nebula. Nevertheless, the low O\u2010anomalous grain abundance is consistent with aqueous alteration occurring in the protosolar nebula and\/or on the respective parent bodies. Six O\u2010rich presolar grains were studied by Auger Electron Spectroscopy, revealing two Fe\u2010rich silicates, one forsterite\u2010like Mg\u2010rich silicate, two Al\u2010oxides with spinel\u2010like compositions, and one Fe\u2010(Mg\u2010)oxide. Scanning electron and transmission electron microscopic investigation of a relatively large silicate grain (490 nm \u00d7 735 nm) revealed that it was crystalline \u00e5kermanite (Ca2Mg[Si2O7]) or a an \u00e5kermanite\u2010diopside (MgCaSi2O6) intergrowth.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Jan Leitner, Knut Metzler, Christian Vollmer, Christine Floss, Pierre Haenecour, J\u00e1nos Kodol\u00e1nyi, Dennis Harries, Peter Hoppe Meteoritics &amp; Planetary Science LINK (OPEN ACCESS) PDF (OPEN ACCESS) &#8220;We investigated the inventory of presolar silicate, oxide, and&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,56,18,65,76],"tags":[402,1842,1594,631,4719,752,1595,107,473,5287,4414,1853,539,5010,1834,1596],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20724"}],"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=20724"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20724\/revisions"}],"predecessor-version":[{"id":20725,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/20724\/revisions\/20725"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=20724"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=20724"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=20724"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}