{"id":36022,"date":"2024-04-22T16:29:08","date_gmt":"2024-04-22T14:29:08","guid":{"rendered":"https:\/\/karmaka.de\/?p=36022"},"modified":"2024-04-22T16:29:10","modified_gmt":"2024-04-22T14:29:10","slug":"oxygen-isotopic-variations-in-the-calcium-aluminum-rich-inclusion-forming-region-recorded-by-a-single-refractory-inclusion-from-the-co3-1-carbonaceous-chondrite-dar-al-gani-083","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=36022","title":{"rendered":"Oxygen Isotopic Variations in the Calcium, Aluminum-rich Inclusion\u2013forming Region Recorded by a Single Refractory Inclusion from the CO3.1 Carbonaceous Chondrite Dar al Gani 083<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Samuel Ebert, Kazuhide Nagashima, Alexander N. Krot, Markus Patzek, and Addi Bischoff<\/p>\n\n\n\n<p>The Astrophysical Journal, Volume 966, Number 1<\/p>\n\n\n\n<p><a href=\"https:\/\/iopscience.iop.org\/article\/10.3847\/1538-4357\/ad2ea8\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/iopscience.iop.org\/article\/10.3847\/1538-4357\/ad2ea8\/pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Calcium, aluminum-rich inclusions (CAIs) are the oldest solids dated that formed in the solar system. Most CAIs in unmetamorphosed chondritic meteorites (chondrites; petrologic type \u22643.0) have uniform solar-like 16O-rich compositions (\u039417O \u223c \u221224\u2030) and a high initial 26Al\/27Al ratio [(26Al\/27Al)0] of \u223c(4\u20135)\u00d710\u22125, consistent with their origin in a gas of approximately solar composition during a brief (&lt;0.3 Ma) epoch at the earliest stage of our solar system. The nature of O-isotope heterogeneity in CAIs (\u039417O range from \u223c\u221224 up to \u223c+5\u2030) from weakly metamorphosed chondrites (petrologic type >3.0) remains an open issue. This heterogeneity could have recorded fluctuations of O-isotope composition of nebular gas in the CAI-forming region and\/or postcrystallization O-isotope exchange of CAI minerals with aqueous fluids on the chondrite parent asteroids. To obtain insights into possible processes resulting in this heterogeneity, we investigated the mineralogy, rare-earth element abundances, and O- and Mg-isotope compositions of a CAI from the CO3.1 chondrite Dar al Gani 083. This concentrically zoned inclusion has a Zn-hercynite core surrounded by layers of (from core to edge) grossite, spinel, melilite, and Al-diopside. The various phases have heterogeneous \u039417O (from core to edge): \u22122.2 \u00b1 0.6\u2030, \u22120.9 \u00b1 2.1\u2030, \u221213.7 \u00b1 2.1\u2030, \u22122.6 \u00b1 2.3\u2030, and \u221222.6 \u00b1 2.1\u2030, respectively. Magnesium-isotope compositions of grossite, spinel, melilite, and Al-diopside define an undisturbed internal Al\u2013Mg isochron with (26Al\/27Al)0of (2.60 \u00b1 0.29)\u00d710\u22126. We conclude that the variations in \u039417O of spinel and diopside recorded fluctuations in O-isotope composition of nebular gas in the CAI-forming region prior to injection and\/or homogenization of 26Al at the canonical level. The 16O depletion of grossite and melilite resulted from O-isotope exchange with asteroidal fluid, which did not disturb Al\u2013Mg isotope systematics of the CAI primary minerals.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Samuel Ebert, Kazuhide Nagashima, Alexander N. Krot, Markus Patzek, and Addi Bischoff The Astrophysical Journal, Volume 966, Number 1 LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;Calcium, aluminum-rich inclusions (CAIs) are the oldest solids dated that formed&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[66,9,19,65,57],"tags":[5708,4292,1846,3830,3273,2914,6362,1845,1945],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36022"}],"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=36022"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36022\/revisions"}],"predecessor-version":[{"id":36023,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36022\/revisions\/36023"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=36022"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=36022"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=36022"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}