{"id":35986,"date":"2024-04-01T23:50:00","date_gmt":"2024-04-01T21:50:00","guid":{"rendered":"https:\/\/karmaka.de\/?p=35986"},"modified":"2024-04-15T18:54:53","modified_gmt":"2024-04-15T16:54:53","slug":"disequilibrium-oxygen-isotope-distribution-among-aqueously-altered-minerals-in-ryugu-asteroid-returned-samples","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=35986","title":{"rendered":"Disequilibrium oxygen isotope distribution among aqueously altered minerals in Ryugu asteroid returned samplesOPEN ACCESS<\/span> "},"content":{"rendered":"\n

Noriko T. Kita, Kouki Kitajima, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Wataru Fujiya, Yoshinari Abe, J\u00e9r\u00f4me Al\u00e9on, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Fr\u00e9d\u00e9ric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Maria Sch\u00f6nb\u00e4chler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto<\/p>\n\n\n\n

MAPS, Version of Record online: 1 April 2024<\/p>\n\n\n\n

LINK (OPEN ACCESS)<\/strong><\/a>
PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n

“Oxygen 3-isotope ratios of magnetite and carbonates in aqueously altered carbonaceous chondrites provide important clues to understanding the evolution of the fluid in the asteroidal parent bodies. We conducted oxygen 3-isotope analyses of magnetite, dolomite, and breunnerite in two sections of asteroid Ryugu returned samples, A0058 and C0002, using a secondary ion mass spectrometer (SIMS). Magnetite was analyzed by using a lower primary ion energy that reduced instrumental biases due to the crystal orientation effect. We found two groups of magnetite data identified from the SIMS pit morphologies: (1) higher \u03b418O (from 3\u2030 to 7\u2030) and \u220617O (~2\u2030) with porous SIMS pits mostly from spherulitic magnetite, and (2) lower \u03b418O (~ \u22123\u2030) and variable \u220617O (0\u2030\u20132\u2030) mostly from euhedral magnetite. Dolomite and breunnerite analyses were conducted using multi-collection Faraday cup detectors with precisions \u22640.3\u2030. The instrumental bias correction was applied based on carbonate compositions in two ways, using Fe and (Fe\u2009+\u2009Mn) contents, respectively, because Ryugu dolomite contains higher amounts of Mn than the terrestrial standard. Results of dolomite and breunnerite analyses show a narrow range of \u220617O; 0.0\u2030\u20130.3\u2030 for dolomite in A0058 and 0.2\u2030\u20130.8\u2030 for dolomite and breunnerite in C0002. The majority of breunnerite, including large \u2265100\u2009\u03bcm grains, show systematically lower \u03b418O (~21\u2030) than dolomite (25\u2030\u201330\u2030 and 23\u2030\u201327\u2030 depending on the instrumental bias corrections). The equilibrium temperatures between magnetite and dolomite from the coarse-grained lithology in A0058 are calculated to be 51\u2009\u00b1\u200911\u00b0C and 78\u2009\u00b1\u200914\u00b0C, depending on the instrumental bias correction scheme for dolomite; a reliable temperature estimate would require a Mn-bearing dolomite standard to evaluate the instrumental bias corrections, which is not currently available. These results indicate that the oxygen isotope ratios of aqueous fluids in the Ryugu parent asteroid were isotopically heterogeneous, either spatially, or temporary. Initial water ice accreted to the Ryugu parent body might have \u220617O\u2009>\u20092\u2030 that was melted and interacted with anhydrous solids with the initial \u220617O\u2009<\u20090\u2030. In the early stage of aqueous alteration, spherulitic magnetite and calcite formed from aqueous fluid with \u220617O\u2009~\u20092\u2030 that was produced by isotope exchange between water (\u220617O\u2009>\u20092\u2030) and anhydrous solids (\u220617O\u2009<\u20090\u2030). Dolomite and breunnerite, along with some magnetite, formed at the later stage of aqueous alteration under higher water-to-rock ratios where the oxygen isotope ratios were nearly at equilibrium between fluid and solid phases. Including literature data, \u03b418O of carbonates decreased in the order calcite, dolomite, and breunnerite, suggesting that the temperature of alteration might have increased with the degree of aqueous alteration.”<\/p>\n","protected":false},"excerpt":{"rendered":"

Noriko T. Kita, Kouki Kitajima, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Wataru Fujiya, Yoshinari Abe, J\u00e9r\u00f4me Al\u00e9on, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61,77,2350,2243],"tags":[3872,1842,1127,3991,701,5037,994,1845,5718,4899,839],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/35986"}],"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=35986"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/35986\/revisions"}],"predecessor-version":[{"id":35987,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/35986\/revisions\/35987"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=35986"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=35986"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=35986"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}