MF研究者総覧

研究者データベース

詳細
川崎　教行(カワサキ　ノリユキ)
理学研究院　地球惑星科学部門　地球惑星システム科学分野
准教授
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Last Updated :2024/05/10

基本情報

所属

  • 理学研究院　地球惑星科学部門　地球惑星システム科学分野

職名

  • 准教授

学位

  • 博士（理学）（北海道大学）

ホームページURL

科研費研究者番号

  • 50770278

J-Global ID

研究キーワード

  • 白色包有物   太陽系   SIMS   質量分析   隕石   宇宙化学   

研究分野

  • 自然科学一般 / 宇宙惑星科学

担当教育組織

職歴

  • 2022年03月 - 現在 北海道大学 大学院理学研究院 地球惑星科学部門 准教授
  • 2018年03月 - 2022年02月 北海道大学 大学院理学研究院 地球惑星科学部門 助教
  • 2016年04月 - 2018年02月 宇宙航空研究開発機構 宇宙科学研究所 宇宙航空プロジェクト研究員
  • 2015年04月 - 2016年03月 日本学術振興会 特別研究員 PD（北海道大学）

所属学協会

  • The Meteoritical Society   日本地球惑星科学連合   日本地球化学会   

研究活動情報

論文

  • Daiki Yamamoto, Noriyuki Kawasaki, Shogo Tachibana, Lily Ishizaki, Ryosuke Sakurai, Hisayoshi Yurimoto
    Geochimica et Cosmochimica Acta 2024年06月 [査読有り]
  • Noriko T. Kita, Kouki Kitajima, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Wataru Fujiya, Yoshinari Abe, Jérôme Aléon, 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, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Maria Schönbächler, 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
    Meteoritics & Planetary Science 2024年04月 [査読有り]
  • Ken-ichi Bajo, Noriyuki Kawasaki, Isao Sakaguchi, Taku T. Suzuki, Satoru Itose, Miyuki Matsuya, Morio Ishihara, Kiichiro Uchino, Hisayoshi Yurimoto
    Analytical Chemistry 96 13 5143 - 5149 2024年03月21日 [査読有り]
  • Yan Hu, Frédéric Moynier, Wei Dai, Marine Paquet, Tetsuya Yokoyama, Yoshinari Abe, Jérôme Aléon, 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, Wataru Fujiya, 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, Noriyuki Kawasaki, Noriko T. Kita, Koki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Mayu Morita, Kazuko Motomura, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, 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
    Icarus 409 115884 - 115884 2024年02月 [査読有り]
  • J. Aléon, S. Mostefaoui, H. Bureau, D. Vangu, H. Khodja, K. Nagashima, N. Kawasaki, Y. Abe, C. M. O'D. Alexander, S. Amari, Y. Amelin, K. Bajo, M. Bizzarro, A. Bouvier, R. W. Carlson, M. Chaussidon, B.‐G. Choi, N. Dauphas, A. M. Davis, T. Di Rocco, W. Fujiya, R. Fukai, I. Gautam, M. K. Haba, Y. Hibiya, H. Hidaka, H. Homma, P. Hoppe, G. R. Huss, K. Ichida, T. Iizuka, T. R. Ireland, A. Ishikawa, S. Itoh, N. T. Kita, K. Kitajima, T. Kleine, S. Komatani, A. N. Krot, M.‐C. Liu, Y. Masuda, M. Morita, K. Motomura, F. Moynier, I. Nakai, A. Nguyen, L. R. Nittler, M. Onose, A. Pack, C. Park, L. Piani, L. Qin, S. S. Russell, N. Sakamoto, M. Schönbächler, L. Tafla, H. Tang, K. Terada, Y. Terada, T. Usui, S. Wada, M. Wadhwa, R. J. Walker, K. Yamashita, Q.‐Z. Yin, T. Yokoyama, S. Yoneda, E. D. Young, H. Yui, A.‐C. Zhang, T. Nakamura, H. Naraoka, T. Noguchi, R. Okazaki, K. Sakamoto, H. Yabuta, M. Abe, A. Miyazaki, A. Nakato, M. Nishimura, T. Okada, T. Yada, K. Yogata, S. Nakazawa, T. Saiki, S. Tanaka, F. Terui, Y. Tsuda, S. Watanabe, M. Yoshikawa, S. Tachibana, H. Yurimoto
    Meteoritics & Planetary Science 2024年01月26日 [査読有り]
  • Van T. H. Phan, Pierre Beck, Rolando Rebois, Eric Quirico, Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A. Ishii, John P. Bradley, Kenta K. Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Dennis Harries, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre‐M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Jérémie Mathurin, Alexandre Dazzi, Emmanuel Dartois, Cécile Engrand, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Peter Hoppe, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐ichiro Watanabe, Yuichi Tsuda
    Meteoritics & Planetary Science 2024年01月08日 [査読有り]
     
    Abstract The Hayabusa2 mission from the Japan Aerospace Exploration Agency (JAXA) returned to the Earth samples of carbonaceous asteroid (162173) Ryugu. This mission offers a unique opportunity to investigate in the laboratory samples from a C‐type asteroid, without physical or chemical alteration by the terrestrial atmosphere. Here, we report on an investigation of the mineralogy and the organo‐chemistry of Hayabusa2 samples using a combination of micro‐ and nano‐infrared spectroscopy. Particles investigated with conventional FTIR spectroscopy have spectra dominated by phyllosilicate‐related absorption, as observed for samples of CI‐chondrites, selected ungrouped carbonaceous chondrites, and selected hydrated micrometeorites. Ryugu samples show smaller sulfate‐related absorption than CI‐chondrites. Our samples that were only briefly exposed to the Earth atmosphere show absorptions related to molecular water, revealing fast terrestrial contamination of the spectral signature at 3 μm. Overall, our FTIR data are in agreement with other work done on Ryugu samples, revealing a low degree of mineralogical variability across Ryugu samples. AFM‐IR mapping of the grains shows the presence of a micrometer‐sized organic globule in one of our analyzed grains. The AFM‐IR spectra obtained on this globule are similar to IR spectra obtained on IOM suggesting that it is constituted of refractory organic matter. This globule may host silicate in its interior, with a different mineralogy than bulk Ryugu phyllosilicate. The shape, presence of peculiar silicate, and the nature of organic constituting the globule point toward a pre‐accretionary origin of this globule and that at least part of Ryugu organics were inherited from the protosolar nebulae or the interstellar media. Altogether, our results show the similarities between Ryugu samples and CI chondrites.
  • Bahae‐eddine Mouloud, Damien Jacob, Francisco de la Peña, Maya Marinova, Corentin Le Guillou, Jean‐Christophe Viennet, Sylvain Laforet, Hugues Leroux, Adrien Teurtrie, Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A. Ishii, John P. Bradley, Kenta K. Ohtaki, Elena Dobrica, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi H. V. Phan, Rolando Rebois, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre‐M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐ichiro Watanabe, Yuichi Tsuda
    Meteoritics & Planetary Science 2024年01月05日 [査読有り]
     
    Abstract Ryugu asteroid grains brought back to the Earth by the Hayabusa2 space mission are pristine samples containing hydrated minerals and organic compounds. Here, we investigate the mineralogy of their phyllosilicate‐rich matrix with four‐dimensional scanning transmission electron microscopy (4D‐STEM). We have identified and mapped the mineral phases at the nanometer scale (serpentine, smectite, pyrrhotite), observed the presence of Ni‐bearing pyrrhotite, and identified the serpentine polymorph as lizardite, in agreement with the reported aqueous alteration history of Ryugu. Furthermore, we have mapped the d‐spacings of smectite and observed a broad distribution of values, ranging from 1 to 2 nm, with an average d‐spacing of 1.24 nm, indicating significant heterogeneity within the sample. Such d‐spacing variability could be the result of either the presence of organic matter trapped in the interlayers or the influence of various geochemical conditions at the submicrometer scale, suggestive of a range of organic compounds and/or changes in smectite crystal chemistry.
  • Mayu Morita, Hiroharu Yui, Shu-hei Urashima, Morihiko Onose, Shintaro Komatani, Izumi Nakai, Yoshinari Abe, Yasuko Terada, Hisashi Homma, Kazuko Motomura, Kiyohiro Ichida, Tetsuya Yokoyama, Kazuhide Nagashima, Jérôme Aléon, 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, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Peter Hoppe, Gary R. Huss, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Sasha Krot, Ming-Chang Liu, Yuki Masuda, Frédéric Moynier, Ann Nguyen, Larry Nittler, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Tommaso Di Rocco, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Edward D. Young, 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
    Analytical Chemistry 2023年12月28日 [査読有り]
  • Zachary A. Torrano, Michelle K. Jordan, Timothy D. Mock, Richard W. Carlson, Ikshu Gautam, Makiko K. Haba, Tetsuya Yokoyama, Yoshinari Abe, Jérôme Aléon, Conel Alexander, Sachiko Amari, Yuri Amelin, Ken‐ichi Bajo, Martin Bizzarro, Audrey Bouvier, Marc Chaussidon, Byeon‐Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor Ireland, Akira Ishikawa, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Koki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming‐Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing‐Zhu Yin, 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
    Meteoritics & Planetary Science 2023年12月07日 [査読有り]
     
    Abstract We report Nd and Sm isotopic compositions of four samples of Ryugu returned by the Hayabusa2 mission, including “A” (first touchdown) and “C” (second touchdown) samples, and several carbonaceous chondrites to evaluate potential genetic relationships between Ryugu and known chondrite groups and track the cosmic ray exposure history of Ryugu. We resolved Nd and Sm isotopic anomalies in small (<20 ng Nd and Sm) sample sizes via thermal ionization mass spectrometer using 1013 Ω amplifiers. Ryugu samples exhibit resolvable negative μ142Nd values consistent with carbonaceous chondrite values, suggesting that Ryugu is related to the parent bodies of carbonaceous chondrites. Ryugu's negative μ149Sm values are the result of exposure to galactic cosmic rays, as demonstrated by the correlation between 150Sm/152Sm and 149Sm/152Sm ratios that fall along the expected neutron capture correlation line. The neutron fluence calculated in the “A” samples (2.75 ± 1.94 × 1015 n cm−2) is slightly higher compared to the “C” samples (0.95 ± 2.04 × 1015 n cm−2), though overlapping within measurement uncertainty. The Sm results for Ryugu, at this level of precision, thus are consistent with a well‐mixed surface layer at least to the depths from which the “A” and “C” samples derive.
  • N. Nakanishi, T. Yokoyama, A. Ishikawa, R.J. Walker, Y. Abe, J. Aléon, C.M.O'D. Alexander, S. Amari, Y. Amelin, K.-I. Bajo, M. Bizzarro, A. Bouvier, R.W. Carlson, M. Chaussidon, B.-G. Choi, N. Dauphas, A.M. Davis, T. Di Rocco, W. Fujiya, R. Fukai, I. Gautam, M.K. Haba, Y. Hibiya, H. Hidaka, H. Homma, P. Hoppe, G.R. Huss, K. Ichida, T. Iizuka, T.R. Ireland, S. Itoh, N. Kawasaki, N.T. Kita, K. Kitajima, T. Kleine, S. Komatani, A.N. Krot, M.-C. Liu, Y. Masuda, M. Morita, K. Motomura, F. Moynier, I. Nakai, K. Nagashima, A. Nguyen, L. Nittler, M. Onose, A. Pack, C. Park, L. Piani, L. Qin, S.S. Russell, N. Sakamoto, M. Schönbächler, L. Tafla, H. Tang, K. Terada, Y. Terada, T. Usui, S. Wada, M. Wadhwa, K. Yamashita, Q.-Z. Yin, S. Yoneda, E.D. Young, H. Yui, A.-C. Zhang, T. Nakamura, H. Naraoka, T. Noguchi, R. Okazaki, K. Sakamoto, H. Yabuta, M. Abe, A. Miyazaki, A. Nakato, M. Nishimura, T. Okada, T. Yada, K. Yogata, S. Nakazawa, T. Saiki, S. Tanaka, F. Terui, Y. Tsuda, S.-I. Watanabe, M. Yoshikawa, S. Tachibana, H. Yurimoto
    Geochemical Perspectives Letters 28 31 - 36 2023年12月 [査読有り]
  • Martin Bizzarro, Martin Schiller, Tetsuya Yokoyama, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, 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, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Mayu Morita, Fréderic Moynier, Kazuko Motomura, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, 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
    The Astrophysical Journal Letters 958 2 L25 - L25 2023年11月24日 [査読有り]
     
    Abstract The nucleosynthetic isotope composition of planetary materials provides a record of the heterogeneous distribution of stardust within the early solar system. In 2020 December, the Japan Aerospace Exploration Agency Hayabusa2 spacecraft returned to Earth the first samples of a primitive asteroid, namely, the Cb-type asteroid Ryugu. This provides a unique opportunity to explore the kinship between primitive asteroids and carbonaceous chondrites. We report high-precision μ26Mg* and μ25Mg values of Ryugu samples together with those of CI, CM, CV, and ungrouped carbonaceous chondrites. The stable Mg isotope composition of Ryugu aliquots defines μ25Mg values ranging from –160 ± 20 ppm to –272 ± 30 ppm, which extends to lighter compositions relative to Ivuna-type (CI) and other carbonaceous chondrite groups. We interpret the μ25Mg variability as reflecting heterogeneous sampling of a carbonate phase hosting isotopically light Mg (μ25Mg ∼ –1400 ppm) formed by low temperature equilibrium processes. After correcting for this effect, Ryugu samples return homogeneous μ26Mg* values corresponding to a weighted mean of 7.1 ± 0.8 ppm. Thus, Ryugu defines a μ26Mg* excess relative to the CI and CR chondrite reservoirs corresponding to 3.8 ± 1.1 and 11.9 ± 0.8 ppm, respectively. These variations cannot be accounted for by in situ decay of 26Al given their respective 27Al/24Mg ratios. Instead, it requires that Ryugu and the CI and CR parent bodies formed from material with a different initial 26Al/27Al ratio or that they are sourced from material with distinct Mg isotope compositions. Thus, our new Mg isotope data challenge the notion that Ryugu and CI chondrites share a common nucleosynthetic heritage.
  • Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A. Ishii, John P. Bradley, Kenta K. Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Bahae‐Eddine Mouloud, Maya Marinova, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi H. V. Phan, Rolando Rebois, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre‐M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, William A. Smith, Sam McFadzean, Pierre‐Etienne Martin, Paul A. J. Bagot, Dennis Fougerouse, David W. Saxey, Steven Reddy, William D. A. Rickard, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Peter Hoppe, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐ichiro Watanabe, Yuichi Tsuda
    Meteoritics & Planetary Science 2023年11月22日 [査読有り]
     
    Abstract Samples returned from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 mission revealed that Ryugu is composed of materials consistent with CI chondrites and some types of space weathering. We report detailed mineralogy of the fine‐grained Ryugu samples allocated to our “Sand” team and report additional space weathering features found on the grains. The dominant mineralogy is composed of a fine‐grained mixture of Mg‐rich saponite and serpentine, magnetite, pyrrhotite, pentlandite, dolomite, and Fe‐bearing magnesite. These grains have mineralogy comparable to that of CI chondrites, showing severe aqueous alteration but lacking ferrihydrite and sulfate. These results are similar to previous works on large Ryugu grains. In addition to the major minerals, we also find many minerals that are rare or have not been reported among CI chondrites. Accessory minerals identified are hydroxyapatite, Mg‐Na phosphate, olivine, low‐Ca pyroxene, Mg‐Al spinel, chromite, manganochromite, eskolaite, ilmenite, cubanite, polydymite, transjordanite, schreibersite, calcite, moissanite, and poorly crystalline phyllosilicate. We also show scanning transmission electron microscope and scanning electron microscope compositional maps and images of some space‐weathered grains and severely heated and melted grains. Although our mineralogical results are consistent with that of millimeter‐sized grains, the fine‐grained fraction is best suited to investigate impact‐induced space weathering.
  • Hugues Leroux, Corentin Le Guillou, Maya Marinova, Sylvain Laforet, Jean‐Christophe Viennet, Bahae‐Eddine Mouloud, Adrien Teurtrie, Francisco de la Peña, Damien Jacob, Daniel Hallatt, Mario Pelaez Fernandez, David Troadec, Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A. Ishii, John P. Bradley, Kenta K. Ohtaki, Elena Dobrică, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi H. V. Phan, Rolando Rebois, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre‐M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tomohiro Usui, Toru Yada, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamotoa, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei‐Ichiro Watanabe, Yuichi Tsuda
    Meteoritics & Planetary Science 2023年11月14日 [査読有り]
     
    Abstract Samples were recently collected from the carbonaceous asteroid (162173) Ryugu, by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 mission. They resemble CI chondrites material, thus showing clear evidence of extensive aqueous alteration attested by the widespread presence of a mixture of serpentine and saponite. We present here a scanning transmission electron microscopy study of the Ryugu dominant lithology of the phyllosilicate matrix at the nanometer scale, which we compare with that of the Orgueil CI chondrite. In both objects, the phyllosilicates are of comparable nature and texture, consisting of a mixture of small‐sized crystallites of serpentine and saponite. At the micrometer scale or less, the texture is an alternation of fine and coarse domains. The fine‐grained regions are dominated by saponite. In Ryugu, they enclose numerous Fe,Ni nanosulfides, whereas in Orgueil, S‐ and Ni‐rich ferrihydrite is abundant. The coarse‐grained regions contain more serpentine and no or little Fe,Ni sulfides or ferrihydrite. Scanning transmission x‐ray microscopy at the Fe‐L3 edge also reveals that iron valency of phyllosilicates is higher and more homogeneous in Orgueil (~70% Fe3+) than in Ryugu (<50% Fe3+). We interpret the observed textures as being mostly a consequence of aqueous alteration, likely resulting from the replacement by phyllosilicates of submicrometric components, initially agglomerated by a primary accretion. The fine‐grained domains may result from the replacement of GEMS (GEMS—glass with embedded metal and sulfides) objects or from other types of nanometric assemblages of silicate and Fe‐based nanophases. On the other hand, the coarse‐grained regions may correspond to the replacement of anhydrous crystalline silicates of the olivine and pyroxene type. The major difference is the presence of Fe,Ni sulfides in Ryugu and of ferrihydrite and higher iron valency of phyllosilicates in Orgueil. This might be due to long‐term terrestrial weathering that would have destabilized the nanosulfides. We also explore an alternative scenario involving more oxidizing hydrothermal conditions on the Orgueil parent body.
  • Tetsuya Yokoyama, Meenakshi Wadhwa, Tsuyoshi Iizuka, Vinai Rai, Ikshu Gautam, Yuki Hibiya, Yuki Masuda, Makiko K. Haba, Ryota Fukai, Rebekah Hines, Nicole Phelan, Yoshinari Abe, Jérôme Aléon, 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, Wataru Fujiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Trevor Ireland, Akira Ishikawa, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Koki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, 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
    Science Advances 9 45 2023年11月10日 [査読有り]
     
    Studies of material returned from Cb asteroid Ryugu have revealed considerable mineralogical and chemical heterogeneity, stemming primarily from brecciation and aqueous alteration. Isotopic anomalies could have also been affected by delivery of exogenous clasts and aqueous mobilization of soluble elements. Here, we show that isotopic anomalies for mildly soluble Cr are highly variable in Ryugu and CI chondrites, whereas those of Ti are relatively uniform. This variation in Cr isotope ratios is most likely due to physicochemical fractionation between 54 Cr-rich presolar nanoparticles and Cr-bearing secondary minerals at the millimeter-scale in the bulk samples, likely due to extensive aqueous alteration in their parent bodies that occurred after Solar System birth. In contrast, Ti isotopes were marginally affected by this process. Our results show that isotopic heterogeneities in asteroids are not all nebular or accretionary in nature but can also reflect element redistribution by water.
  • Haolan Tang, Edward D. Young, Lauren Tafla, Andreas Pack, Tommaso Di Rocco, Yoshinari Abe, Jérôme Aléon, 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, Wataru Fujiya, 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, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Kazuhide Nagashima, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, 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
    The Planetary Science Journal 4 8 144 - 144 2023年08月 
    Abstract We present oxygen isotopic analyses of fragments of the near-Earth Cb-type asteroid Ryugu returned by the Hayabusa2 spacecraft that reinforce the close correspondence between Ryugu and CI chondrites. Small differences between Ryugu samples and CI chondrites in ${ { \rm{\Delta } } }^{ { \prime} 17},{\rm{O } }$ can be explained at least in part by contamination of the latter by terrestrial water. The discovery that a randomly sampled C-complex asteroid is composed of CI-chondrite-like rock, combined with thermal models for formation prior to significant decay of the short-lived radioisotope 26Al, suggests that if lithified at the time of alteration, the parent body was small (≪50 km radius). If the parent planetesimal was large (>50 km in radius), it was likely composed of high-permeability, poorly lithified sediment rather than consolidated rock.
  • Ann. N. Nguyen, Prajkta Mane, Lindsay P. Keller, Laurette Piani, Yoshinari Abe, Jérôme Aléon, 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, Wataru Fujiya, 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, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, 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
    Science Advances 9 28 2023年07月14日 [査読有り][通常論文]
     
    Preliminary analyses of asteroid Ryugu samples show kinship to aqueously altered CI (Ivuna-type) chondrites, suggesting similar origins. We report identification of C-rich, particularly primitive clasts in Ryugu samples that contain preserved presolar silicate grains and exceptional abundances of presolar SiC and isotopically anomalous organic matter. The high presolar silicate abundance (104 ppm) indicates that the clast escaped extensive alteration. The 5 to 10 times higher abundances of presolar SiC (~235 ppm), N-rich organic matter, organics with N isotopic anomalies (1.2%), and organics with C isotopic anomalies (0.2%) in the primitive clasts compared to bulk Ryugu suggest that the clasts formed in a unique part of the protoplanetary disk enriched in presolar materials. These clasts likely represent previously unsampled outer solar system material that accreted onto Ryugu after aqueous alteration ceased, consistent with Ryugu’s rubble pile origin.
  • Wataru Fujiya, Noriyuki Kawasaki, Kazuhide Nagashima, Naoya Sakamoto, Conel M. O’D. Alexander, Noriko T. Kita, Kouki Kitajima, Yoshinari Abe, Jérôme Aléon, 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, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Maria Schönbächler, 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
    Nature Geoscience 16 8 675 - 682 2023年07月10日 [査読有り]
  • Noriyuki Kawasaki, Daiki Yamamoto, Sohei Wada, Changkun Park, Hwayoung Kim, Naoya Sakamoto, Hisayoshi Yurimoto
    Meteoritics & Planetary Science 2023年05月15日 [査読有り]
  • Laurette Piani, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Ken-ichi Bajo, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, 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, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Liping Qin, Sara S. Russell, Maria Schönbächler, 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, 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
    The Astrophysical Journal Letters 946 2 L43 - L43 2023年04月01日 [査読有り]
     
    Abstract Rock fragments of the Cb-type asteroid Ryugu returned to Earth by the JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with the Ivuna-type (CI) carbonaceous chondrites. Similar to CI chondrites, these fragments underwent extensive aqueous alteration and consist predominantly of hydrous minerals likely formed in the presence of liquid water on the Ryugu parent asteroid. Here we present an in situ analytical survey performed by secondary ion mass spectrometry from which we have estimated the D/H ratio of Ryugu’s hydrous minerals, D/HRyugu, to be [165 ± 19] × 10−6, which corresponds to δDRyugu = +59 ± 121‰ (2σ). The hydrous mineral D/HRyugu’s values for the two sampling sites on Ryugu are similar; they are also similar to the estimated D/H ratio of hydrous minerals in the CI chondrites Orgueil and Alais. This result reinforces a link between Ryugu and CI chondrites and an inference that Ryugu’s samples, which avoided terrestrial contamination, are our best proxy to estimate the composition of water at the origin of hydrous minerals in CI-like material. Based on this data and recent literature studies, the contribution of CI chondrites to the hydrogen of Earth’s surficial reservoirs is evaluated to be ∼3%. We conclude that the water responsible for the alteration of Ryugu’s rocks was derived from water ice precursors inherited from the interstellar medium; the ice partially re-equilibrated its hydrogen with the nebular H2 before being accreted on the Ryugu’s parent asteroid.
  • 川﨑 教行
    地球化学 57 1 1 - 12 2023年03月25日 [査読有り][招待有り]
  • Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A. Ishii, John P. Bradley, Kenta K. Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi H. V. Phan, Rolando Rebois, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre-M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Masahiko Arakawa, Atsushi Fujii, Masahiko Hayakawa, Naru Hirata, Naoyuki Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kousuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Ryudo Tsukizaki, Koji Wada, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Ryohta Fukai, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Hiromichi Soejima, Ayako I. Suzuki, Tomohiro Usui, Toru Yada, Daiki Yamamoto, Kasumi Yogata, Miwa Yoshitake, Harold C. Connolly, Dante S. Lauretta, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 7 2 170 - 181 2022年12月19日 
    Abstract Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.
  • Noriyuki Kawasaki, Kazuhide Nagashima, Naoya Sakamoto, Toru Matsumoto, Ken-ichi Bajo, Sohei Wada, Yohei Igami, Akira Miyake, Takaaki Noguchi, Daiki Yamamoto, Sara S. Russell, Yoshinari Abe, Jérôme Aléon, Conel M, O'D. Alexander, Sachiko Amari, Yuri Amelin, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Irelan, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Noriko T. Kita, Kouki Kitajim, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Meenakshi Wadhw, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, 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
    Science Advances 8 50 2022年12月17日 [査読有り][通常論文]
     
    The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16 O-rich (associated with refractory inclusions) and 16 O-poor (associated with chondrules). Both the 16 O-rich and 16 O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16 O-rich to 16 O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.
  • Marine Paquet, Frederic Moynier, Tetsuya Yokoyama, Wei Dai, Yan Hu, Yoshinari Abe, Jérôme Aléon, 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, Wataru Fujiya, 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, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann N. Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, 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
    Nature Astronomy 7 2 182 - 189 2022年12月12日 [査読有り]
     
    Initial analyses showed that asteroid Ryugu’s composition is close to CI (Ivuna-like) carbonaceous chondrites (CCs) – the chemically most primitive meteorites, characterized by near-solar abundances for most elements. However, some isotopic signatures (for example, Ti, Cr) overlap with other CC groups, so the details of the link between Ryugu and the CI chondrites are not yet fully clear. Here we show that Ryugu and CI chondrites have the same zinc and copper isotopic composition. As the various chondrite groups have very distinct Zn and Cu isotopic signatures, our results point at a common genetic heritage between Ryugu and CI chondrites, ruling out any affinity with other CC groups. Since Ryugu’s pristine samples match the solar elemental composition for many elements, their Zn and Cu isotopic compositions likely represent the best estimates of the solar composition. Earth’s mass-independent Zn isotopic composition is intermediate between Ryugu/CC and non-carbonaceous chondrites (NCs), suggesting a contribution of Ryugu-like material to Earth’s budgets of Zn and other moderately volatile elements.
  • Timo Hopp, Nicolas Dauphas, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, 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, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, 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
    Science Advances 8 46 eadd8141  2022年11月18日 [査読有り]
     
    Little is known about the origin of the spectral diversity of asteroids and what it says about conditions in the protoplanetary disk. Here, we show that samples returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguishable from Ivuna-type (CI) chondrites, which are distinct from all other carbonaceous chondrites. Iron isotopes, therefore, demonstrate that Ryugu and CI chondrites formed in a reservoir that was different from the source regions of other carbonaceous asteroids. Growth and migration of the giant planets destabilized nearby planetesimals and ejected some inward to be implanted into the Main Belt. In this framework, most carbonaceous chondrites may have originated from regions around the birthplaces of Jupiter and Saturn, while the distinct isotopic composition of CI chondrites and Ryugu may reflect their formation further away in the disk, owing their presence in the inner Solar System to excitation by Uranus and Neptune.
  • Daiki Yamamoto, Noriyuki Kawasaki, Shogo Tachibana, Michiru Kamibayashi, Hisayoshi Yurimoto
    Geochimica et Cosmochimica Acta 336 104 - 112 2022年11月 [査読有り]
     
    Coarse-grained igneous calcium-aluminum-rich inclusions (CAIs) are suggested to have experienced gas-melt isotope exchange of oxygen during the melting events of their precursors. Therefore, their oxygen isotope variation would preserve information about the high-temperature processes in the earliest Solar System. We experimentally determined oxygen isotope exchange kinetics between CAI analog melt and carbon monoxide (CO) gas at 1420 degrees C and 1460 degrees C under CO gas partial pressures of 0.1, 0.5, and 1 Pa to understand the role of CO gas on the oxygen isotope exchange. We observed oxygen isotope zoning profiles inside the reacted samples that formed through the oxygen isotope exchange reaction at the melt surface and oxygen diffusion in the melt. The zoning profiles were fitted using a three-dimensional spherical diffusion model with time-dependent surface concentration. The oxygen isotope exchange efficiency for colliding CO molecules is estimated to be similar to 3.3 x 10(-4), which is much smaller than that for H2O (0.28). The oxygen diffusion coefficient obtained in this study is similar to that obtained in the oxygen isotope exchange experiments between the CAI melt and H2O, suggesting that the diffusion species in the melt is O2-, despite the surrounding atmospheres.A comparison of the isotope exchange reaction kinetics between (1) CAI melt and CO gas, (2) CAI melt and H2O gas, and (3) CO and H2O gases shows that the reaction rate decreases in the order of (3), (2), and (1). The rapid isotope exchange of the reaction (1) indicates that the oxygen isotopic compositions of H2O and CO should have been equilibrated during the melting and crystallization processes of igneous CAIs. Both H2O and CO change the oxygen isotope compositions of molten CAI in the same direction, although reaction (2) controls the isotope exchange timescale between the CAI melt and surrounding gas. Our dataset demonstrates that type B CAIs having melilite with homogeneous oxygen isotope composition should have been heated for 2-3 days at P-H2 > 100 Pa above the melilite liquidus (similar to 1400 degrees C) in the solar protoplanetary disk. (C) 2022 Elsevier Ltd. All rights reserved.
  • F. Moynier, W. Dai, T. Yokoyama, Y. Hu, M. Paquet, Y. Abe, J. Aléon, C.M.O'D Alexander, S. Amari, Y. Amelin, K.-I. Bajo, M. Bizzarro, A. Bouvier, R.W. Carlson, M. Chaussidon, B.-G. Choi, N. Dauphas, A.M. Davis, T. Di Rocco, W. Fujiya, R. Fukai, I. Gautam, M.K. Haba, Y. Hibiya, H. Hidaka, H. Homma, P. Hoppe, G.R. Huss, K. Ichida, T. Iizuka, T.R. Ireland, A. Ishikawa, M. Ito, S. Itoh, N. Kawasaki, N.T. Kita, K. Kitajima, T. Kleine, S. Komatani, A.N. Krot, M.-C. Liu, Y. Masuda, K.D. McKeegan, M. Morita, K. Motomura, I. Nakai, K. Nagashima, D. Nesvorný, A. Nguyen, L. Nittler, M. Onose, A. Pack, C. Park, L. Piani, L. Qin, S.S. Russell, N. Sakamoto, M. Schönbächler, L. Tafla, H. Tang, K. Terada, Y. Terada, T. Usui, S. Wada, M. Wadhwa, R.J. Walker, K. Yamashita, Q.-Z. Yin, S. Yoneda, E.D. Young, H. Yui, A.-C. Zhang, T. Nakamura, H. Naraoka, T. Noguchi, R. Okazaki, K. Sakamoto, H. Yabuta, M. Abe, A. Miyazaki, A. Nakato, M. Nishimura, T. Okada, T. Yada, K. Yogata, S. Nakazawa, T. Saiki, S. Tanaka, F. Terui, Y. Tsuda, S.-I. Watanabe, M. Yoshikawa, S. Tachibana, H. Yurimoto
    Geochemical Perspectives Letters 24 1 - 6 2022年10月 [査読有り]
     
    The Hayabusa2 spacecraft has returned samples from the Cb-type asteroid (162173) Ryugu to Earth. Previous petrological and chemical analyses support a close link between Ryugu and CI chondrites that are presumed to be chemically the most primitive meteorites with a solar-like composition. However, Ryugu samples are highly enriched in Ca compared to typical CI chondrites. To identify the cause of this discrepancy, here we report stable Ca isotopic data (expressed as δ44/40CaSRM915a) for returned Ryugu samples collected from two sites. We found that samples from both sites have similar δ44/40CaSRM915a (0.58 ± 0.03 % and 0.55 ± 0.08 %, 2 s.d.) that fall within the range defined by CIs. This isotopic similarity suggests that the Ca budget of CIs and Ryugu samples is dominated by carbonates, and the variably higher Ca contents in Ryugu samples are due to the abundant carbonates. Precipitation of carbonates on Ryugu likely coincided with a major episode of aqueous activity dated to have occurred ∼5 Myr after Solar System formation. Based on the pristine Ryugu samples, the average δ44/40CaSRM915a of the Solar System is defined to be 0.57 ± 0.04 % (2 s.d.).
  • Jens Barosch, Larry R. Nittler, Jianhua Wang, Conel M. O'D Alexander, Bradley T. De Gregorio, Cecile Engrand, Yoko Kebukawa, Kazuhide Nagashima, Rhonda M. Stroud, Hikaru Yabuta, Yoshinari Abe, Jerome Aleon, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Laure Bejach, Martin Bizzarro, Lydie Bonal, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, George D. Cody, Emmanuel Dartois, Nicolas Dauphas, Andrew M. Davis, Alexandre Dazzi, Ariane Deniset-Besseau, Tommaso Di Rocco, Jean Duprat, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Minako Hashiguchi, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Kanami Kamide, Noriyuki Kawasaki, A. L. David Kilcoyne, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Mutsumi Komatsu, Alexander N. Krot, Ming-Chang Liu, Zita Martins, Yuki Masuda, Jeremie Mathurin, Kevin D. McKeegan, Gilles Montagnac, Mayu Morita, Smail Mostefaoui, Kazuko Motomura, Frederic Moynier, Izumi Nakai, Ann N. Nguyen, Takuji Ohigashi, Taiga Okumura, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Eric Quirico, Laurent Remusat, Sara S. Russell, Naoya Sakamoto, Scott A. Sandford, Maria Schonbachler, Miho Shigenaka, Hiroki Suga, Lauren Tafla, Yoshio Takahashi, Yasuo Takeichi, Yusuke Tamenori, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Maximilien Verdier-Paoletti, Sohei Wada, Meenakshi Wadhwa, Daisuke Wakabayashi, Richard J. Walker, Katsuyuki Yamashita, Shohei Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Shogo Tachibana, Hisayoshi Yurimoto
    ASTROPHYSICAL JOURNAL LETTERS 935 1 2022年08月 [査読有り]
     
    We have conducted a NanoSIMS-based search for presolar material in samples recently returned from C-type asteroid Ryugu as part of JAXA's Hayabusa2 mission. We report the detection of all major presolar grain types with O- and C-anomalous isotopic compositions typically identified in carbonaceous chondrite meteorites: 1 silicate, 1 oxide, 1 O-anomalous supernova grain of ambiguous phase, 38 SiC, and 16 carbonaceous grains. At least two of the carbonaceous grains are presolar graphites, whereas several grains with moderate C isotopic anomalies are probably organics. The presolar silicate was located in a clast with a less altered lithology than the typical extensively aqueously altered Ryugu matrix. The matrix- normalized presolar grain abundances in Ryugu are 4.8(-2.6)(+4.7) ppm for O-anomalous grains, 25(-)(5)(+)(6) ppm for SiC grains, and 11(-3)(+5) ppm for carbonaceous grains. Ryugu is isotopically and petrologically similar to carbonaceous Ivuna-type (CI) chondrites. To compare the in situ presolar grain abundances of Ryugu with CI chondrites, we also mapped Ivuna and Orgueil samples and found a total of 15 SiC grains and 6 carbonaceous grains. No O-anomalous grains were detected. The matrix-normalized presolar grain abundances in the CI chondrites are similar to those in Ryugu: 23(-6)(+7) ppm SiC and 9.0 (+5.4)(-3)(.6) ppm carbonaceous grains. Thus, our results provide further evidence in support of the Ryugu-CI connection. They also reveal intriguing hints of small-scale heterogeneities in the Ryugu samples, such as locally distinct degrees of alteration that allowed the preservation of delicate presolar material.
  • Tetsuya Yokoyama, Kazuhide Nagashima, Izumi Nakai, Edward D. Young, Yoshinari Abe, Jérôme Aléon, 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, Wataru Fujiya, 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, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Hiroharu Yui, Ai-Cheng Zhang, Harold C. Connolly, Dante S. Lauretta, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Masahiko Arakawa, Atsushi Fujii, Masahiko Hayakawa, Naoyuki Hirata, Naru Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kosuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Yuichi Tsuda, Ryudo Tsukizaki, Koji Wada, Sei-ichiro Watanabe, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Hiromichi Soejima, Ayako Suzuki, Toru Yada, Daiki Yamamoto, Kasumi Yogata, Miwa Yoshitake, Shogo Tachibana, Hisayoshi Yurimoto
    Science 379 6634 eabn7850  2022年06月09日 [査読有り]
     
    Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measure the mineralogy, bulk chemical and isotopic compositions of Ryugu samples. They are mainly composed of materials similar to carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37 ± 10°C, (Stat.) (Syst.) million years after formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles the Sun’s photosphere than other natural samples do.
  • Michiru Kamibayashi, Shogo Tachibana, Daiki Yamamoto, Noriyuki Kawasaki, Hisayoshi Yurimoto
    The Astrophysical Journal Letters 923 1 L12 - L12 2021年12月01日 [査読有り][通常論文]
     
    Abstract Calcium–aluminum-rich inclusions (CAIs) are the oldest materials that formed in the protosolar disk. Igneous CAIs experienced melting and subsequent crystallization in the disk during which the evaporation of relatively volatile elements such as Mg and Si occurred. Evaporation from the melt would have played a significant role in the variation of chemical, mineralogical, and petrologic characteristics of the igneous CAIs. In this study, we investigated crystallization of CAI analog melt under disk-like low-pressure hydrogen (PH2) conditions of 0.1, 1, and 10 Pa to constrain the pressure condition of the early solar system in which type B CAIs were formed. At PH2 = 10 Pa, the samples were mantled by melilite crystals, as observed for type B1 CAIs. However, the samples heated at PH2 = 0.1 Pa exhibited random distribution of melilite, as in type B2 CAIs. At the intermediate PH2 of 1 Pa, type-B1-like structure formed when the cooling rate was 5°C hr−1, whereas the formation of type-B2-like structure required a cooling rate faster than 20°C hr−1. The compositional characteristics of melilite in type B1 and B2 CAIs could also be reproduced by experiments. The results of the present study suggest that PH2 required for type-B1-like textural and chemical characteristics is greater than 1 Pa. The hydrogen pressure estimated in this study would impose an important constraint on the physical condition of the protosolar disk where type B CAIs were formed.
  • May Sas, Phil Shane, Noriyuki Kawasaki, Naoya Sakamoto, Georg F. Zellmer, Hisayoshi Yurimoto
    Journal of Volcanology and Geothermal Research 421 107430 - 107430 2021年11月 [査読有り][通常論文]
     
    The sources and processes involved in the genesis of the voluminous rhyolitic magmas of cataclysmic calderaforming eruptions, and the intervening lower-volume intra-caldera extrusions, have been subject to much debate. To better understand generation of high-volume and low-volume silicic eruptions within a single volcanic centre, and how they may differ, we examined ten volumetrically varied high-SiO2 rhyolite eruptions from the Okataina Volcanic Centre (OVC) in Aotearoa New Zealand. The OVC is one of the world'smost recurrently active silicic volcanoes. In the last similar to 600 ky, the OVCwas the focus of three knowncaldera-forming events and numerous intermittent dome-building and fissure eruption episodes, with rhyolitic eruption activity as recent as 1314 CE. To elucidate how mass contributions from the mantle and crust may have fluctuated over the lifespan of the OVC magmatic system, oxygen isotopic ratios (delta O-18) of quartz in rhyolites were investigated for the first time at inter-crystal and intra-crystal scales. Quartz crystals from four eruption episodes (two caldera-forming events, Utu, similar to 557 ka, Rotoiti, similar to 45 ka, and two intra-caldera dome-building events, Rotoma, similar to 9.5 ka, and Kaharoa, similar to 0.7 ka) yielded intra-crystal delta O-18 isotopic homogeneity (+/- 0.23 parts per thousand, 2sd) based on secondary ion mass spectrometry (SIMS). These samples also display inter-crystal and inter-unit homogeneity within slightly lower precision (7.6 +/- 0.5%, 2sd). Whole-crystal quartz from the same four units, as well as six other units (two intra-caldera dome-building episodes, Okareka, similar to 21.8 ka, Whakatane, similar to 5.5 ka, three pre-Rotoiti extra-caldera domes, Round Hill, Haparangi, Kakapiko, and one immediately post-Rotoiti eruption, Earthquake Flat), were then examined using high-precision laser fluorination. Single crystals also yielded mostly homogenous ratios with average delta O-18= 7.6 +/- 0.5 parts per thousand (2sd), which is consistent with intra-crystal SIMS analyses, albeit for a larger set of samples. Stable and radiogenic isotope mixing models using the newly obtained delta O-18 ratios demonstrate that OVC rhyolites can be produced by >= 25% assimilation of a regional (Torlesse-like) metasedimentary endmember by a depletedmantle sourcewith slightly variable amounts of subduction flux, and that any incorporation of hydrothermally alteredmaterial to the systemis limited to<5% in caldera and intra-caldera eruptions. The delta O-18 records of the OVC are among the most homogenous currently known and indicate stable and consistent mantle and crustal contributions across the lifespan of the magmatic system, with assimilation largely occurring prior to segregation of rhyolitic melts within the silicic reservoir. This isotopic homogeneity may be due to a relatively high-volume and constant magma flux at the OVC, which contrasts to other rhyolitic caldera volcanoes with greater isotopic variability. (C) 2021 Elsevier B.V. All rights reserved.
  • Daiki Yamamoto, Noriyuki Kawasaki, Shogo Tachibana, Michiru Kamibayashi, Hisayoshi Yurimoto
    Geochimica et Cosmochimica Acta 314 108 - 120 2021年09月 [査読有り]
  • Noriyuki Kawasaki, Shoichi Itoh, Naoya Sakamoto, Steven B. Simon, Daiki Yamamoto, Hisayoshi Yurimoto
    Meteoritics & Planetary Science 56 6 1224 - 1239 2021年06月07日 [査読有り]
     
    Coarse-grained, igneous Ca-Al-rich inclusions (CAIs) in CV chondrites formed through multiple melting events. We conducted in situ O-isotope analysis and Al-Mg systematics by secondary ion mass spectrometry of relict and overgrown minerals from a partial melting event in an Allende Type B CAI, Golfball. Golfball has a Type B CAI bulk composition and a unique structure: a fassaite-rich mantle enclosing a melilite-rich core. Many of the blocky melilite crystals in the core have irregularly shaped, Al-rich (Åk5–15) cores enclosed in strongly zoned (Åk30–70) overgrowths. Since the Al-rich melilite grains could not have formed from a melt of Golfball, they are interpreted as relict grains that survived later melting events. The O-isotopic compositions of the blocky melilite crystals plot along the carbonaceous chondrite anhydrous mineral line, ranging between Δ17O ~ −14‰ and −5‰. The Al-rich relict melilite grains and their overgrowths exhibit the same O-isotopic compositions, while the O-isotopic compositions are varied spatially among melilites. We found that the O-isotopic compositions steeply change across several melilite crystals within few tens of micrometers, indicating the O-isotopic compositions of the melt could not have been homogenized during the partial melting in that scale. According to the time scale of O self-diffusivity in the melt, the cooling rate of the partial melting event is calculated to be >6 × 104 K h−1. Al-Mg isotope data for core minerals plot on a straight line on an Al-Mg evolution diagram. A mineral isochron for Golfball gives initial 26Al/27Al of (4.42 ± 0.20) × 10–5 and initial δ26Mg* of −0.035 ± 0.050‰. The chemical and O-isotopic compositions of melilite and those initial values imply that its precursor consisted of fluffy Type A and/or fine-grained CAIs. The partial melting event for Golfball may have occurred in very short order after the precursor formation.
  • Akimasa Suzumura, Noriyuki Kawasaki, Yusuke Seto, Hisayoshi Yurimoto, Shoichi Itoh
    GEOCHIMICA ET COSMOCHIMICA ACTA 303 51 - 65 2021年06月 [査読有り]
     
    We report the in-situ oxygen isotopic distributions corresponding to the petrographic-mineralogical observation on a compact Type A (CTA) Ca-Al-rich inclusion (CAI), KU-N-02, from a reduced CV3 chondrite, Northwest Africa 7865. The CTA has an igneous texture and mainly consists of spinel, melilite, and Al-Ti-rich clinopyroxene (fassaite). Oxygen isotopic compositions of the constituent minerals plot along the carbonaceous chondrite anhydrous mineral line. The spinel grains are poikilitically enclosed in the melilite and fassaite and are uniformly O-16-rich (Delta O-17 = approximately - 23 parts per thousand). The fassaite is texturally classified into two types: blocky fassaite and intergranular fassaite. The blocky fassaite crystals exhibit growth zoning as they change from Ti-rich to Ti-poor along the inferred directions of crystal growth from core to rim, while the oxygen isotopic compositions change from O-16-poor (Delta O-17 = approximately - 6 parts per thousand) to O-16-rich (Delta O-17 = approximately - 23 parts per thousand) with crystal growth. The intergranular fassaite crystals exist between the melilite crystals and exhibit variable Ti abundance and oxygen isotopic compositions. Additionally, their relationships between Ti contents and oxygen isotopic composition are similar to those of the blocky fassaite. The melilite grains are homogeneously O-16-poor (Delta O-17 = approximately - 2 parts per thousand), irrespective of their akermanite (angstrom k) content. Each melilite grain generally exhibits growth zoning with increasing angstrom k contents from core to rim, although the melilite contains angstrom k-rich patches within single crystal. angstrom k-rich patches often include two types of fassaite: small blebby crystals attached to spinel crystals and round crystals. The oxygen isotopic compositions of the angstrom k-rich patch and blebby fassaite are O-16-poor (Delta O-17 = approximately - 2 parts per thousand), similar to that of the host melilite. On the other hand, the round fassaite exhibits significant variation in oxygen isotopic compositions ranging from Delta O-17= -23 parts per thousand to -4 parts per thousand, which are different from those of the host melilite. These petrographic textures and oxygen isotopic variations indicate the presence of a solid precursor with variable oxygen isotopic compositions for the CTA. The spinel and round fassaite grains are relicts of the precursor that melted in the O-16-poor nebular gas, resulting in the crystallization of the host melilite from the O-16-poor melt. The angstrom k-rich patches and blebby fassaite crystallized from melts trapped by the growing host melilite crystals. The blocky and intergranular fassaite crystallized after the melilite did, and the oxygen isotopic composition of the melt changed to O-16-rich during the crystallization process, suggesting that the oxygen isotopic composition of the surrounding nebular gas could be varied. The inferred oxygen isotopic evolution for CTA is consistent with those inferred for Type B CAIs, suggesting that coarse-grained igneous CAIs formed in a similar nebular environment regardless of precursor chemistry. (C) 2021 Elsevier Ltd. All rights reserved.
  • Yoko Kebukawa, Sachio Kobayashi, Noriyuki Kawasaki, Ying Wang, Hisayoshi Yurimoto, George D. Cody
    METEORITICS & PLANETARY SCIENCE 56 3 440 - 454 2021年03月 [査読有り]
     
    The large variations in hydrogen isotope ratios found in insoluble organic matter (IOM) in chondritic meteorites may be attributed to hydrogen isotopic exchange between IOM and water during aqueous alteration. We conducted D-H exchange experiments (1) during synthesis of IOM simulant (hereafter called chondritic organic analog, COA) from formaldehyde, glycolaldehyde, and ammonia with water, and (2) with the synthesized COA with a secondary reservoir of water. The changes in the D/H ratios obtained by infrared spectra of the COA suggest that most of the hydrogen in the COA is derived from water during synthesis. We further investigated the kinetics of D-H exchange between D-rich COA and D-poor water, as well as the opposite case, D-poor COA and D-rich water. To help assess understanding exchange kinetics, two-dimensional isotope imaging obtained using isotope microscope revealed that no gradient D-H exchange profiles were present in the COA grains, indicating that the rate-limiting step for D-H exchange is not diffusion. Thus, the changes in D/(D + H) ratios were fit by the first-order reaction rate law. Apparent kinetic parameters-the rate constants, the activation energies, and the frequency factors-were obtained with the Arrhenius equation. Using these kinetic expressions, hydrogen isotopic exchange profiles were estimated for time and temperature behavior. The D-H exchange between organic matter and water is apparently relatively fast and this implies that the aqueous alteration temperatures should have been very low, likely close to 0 degrees C to maintain hydrogen isotopic disequilibrium between organic matter and liquid water for millions of years.
  • Noriyuki Kawasaki, Changkun Park, Shigeyuki Wakaki, Hwayoung Kim, Sunyoung Park, Toshihiro Yoshimura, Kazuya Nagaishi, Hyun Na Kim, Naoya Sakamoto, Hisayoshi Yurimoto
    GEOCHEMICAL JOURNAL 55 4 283 - 287 2021年 [査読有り]
     
    Instrumental mass fractionation of Mg-isotopes and the relative sensitivity factor (RSF) for Al-27/Mg-24 ratios for in situ analysis by secondary ion mass spectrometry were investigated for minerals in Ca-Al-rich inclusions (CAIs) of meteorites, to verify systematic errors in Al-Mg chronological systematics of CAIs. We synthesized seventeen glasses with different chemical compositions that imitate those for CAI minerals and measured their Al-Mg isotopic compositions. In particular, the variation range of RSFs for six melilite glasses almost covering chemical compositions of CAI melilite is 2.0 +/- 0.3%, indicating that systematic error for Al-27/Mg-24 for melilite is less than 2.0 +/- 0.3% and likely corresponds to that of an Al-26-Mg-26 relative age of similar to 0.01 Myr for melilite-rich CAIs. Our data strongly support the robustness of variations in initial Al-26/Al-27 ratios among CAIs, corresponding to a formation age spread of similar to 0.4 Myr at the very beginning of the Solar System formation.
  • Takayuki Nonoyama, Lei Wang, Masumi Tsuda, Yuki Suzuki, Ryuji Kiyama, Kazunori Yasuda, Shinya Tanaka, Kousuke Nagata, Ryosuke Fujita, Naoya Sakamoto, Noriyuki Kawasaki, Hisayoshi Yurimoto, Jian Ping Gong
    Advanced healthcare materials 10 3 e2001731  2020年11月16日 [査読有り]
     
    Tough double network (DN) hydrogels are promising substitutes of soft supporting tissues such as cartilage and ligaments. For such applications, it is indispensable to robustly fix the hydrogels to bones with medically feasible methods. Recently, robustly bonding the DN hydrogels to defected bones of rabbits in vivo has been proved successful. The low crystalline hydroxyapatite (HAp) of calcium-phosphate-hydroxide salt coated on the surface layer of the DN hydrogels induced spontaneous osteogenesis penetrating into the semi-permeable hydrogels to form a gel/bone composite layer. In this work, the 44 Ca isotope-doped HAp/DN hydrogel is implanted in a defect of rabbit femoral bone and the dynamic osteogenesis process at the gel/bone interface is analyzed by tracing the calcium isotope ratio using isotope microscopy. The synthetic HAp hybridized on the surface layer of DN gel dissolves rapidly in the first two weeks by inflammation, and then the immature bone with a gradient structure starts to form in the gel region, reutilizing the dissolved Ca ions. These results reveal, for the first time, that synthetic HAp is reutilized for osteogenesis. These facts help to understand the lifetime of bone absorbable materials and to elucidate the mechanism of spontaneous, non-toxic, but strong fixation of hydrogels to bones.
  • Sohei Wada, Noriyuki Kawasaki, Changkun Park, Hisayoshi Yurimoto
    GEOCHIMICA ET COSMOCHIMICA ACTA 288 161 - 175 2020年11月 [査読有り]
     
    Fine-grained Ca-Al-rich inclusions (FGIs) in CV chondrites are suggested to be condensates from the solar nebular gas and thus captured O-isotopes from the gas. We conducted a combined study of petrographic observations and in situ O-isotope analysis using secondary ion mass spectrometry for an FGI, named HKD01, from the reduced CV chondrite Northwest Africa 8613. HKD01 has an irregular shape and petrographically three-layered structures: a hibonite-rich core, a spinel-rich core, and a mantle. Each petrographic domain contains melilite, hibonite, and spinel with variable proportions of those minerals. The O-isotopic compositions of the constituent minerals plotted along the slope-1 line on an O three-isotope diagram ranged between Delta O-17 similar to 23 parts per thousand and 1 parts per thousand. Hibonite and spinel are uniformly O-16-rich (Delta O-17 = similar to 23 parts per thousand) irrespective of their occurrences, while melilite crystals exhibit wide O-isotope variations ranging between 4 O-17 similar to -23 parts per thousand and 1 parts per thousand. The O-isotopic composition in a melilite crystal changes abruptly within similar to 2 mu m, indicating that disturbances of O-isotopes in melilite after condensation are less than similar to 2 mu m. Because the melilite in the FGI typically has grain sizes of 5-10 mu m, the abrupt change of O-isotopic composition demonstrates that melilite crystals in the FGI preserve the O-isotopic composition of the nebular gas from which they condensed. In the mantle, aggregates of melilite crystals, having relatively large grain sizes (10-25 mu m) and oscillatory chemical zoning, exhibit O-16-poor compositions with small variations ranging between Delta O-17 similar to -4 and 1 parts per thousand. Among them, a large melilite crystal (similar to 20 mu m) with homogeneously O-16-poor composition (Delta O-17 similar to 0 parts per thousand) across the single crystal was found. The coexistence of O-16-poor and O-16-rich melilite crystals without O-isotope disturbances in the FGI reveals that O-16-poor (Delta O-17 similar to 0 parts per thousand) nebular gas existed in the formation region of the FGI HKD01 in addition to O-16-rich (Delta O-17 similar to-23 parts per thousand) nebular gas. (C) 2020 Elsevier Ltd. All rights reserved.
  • Yong Xiong, Ai-Cheng Zhang, Noriyuki Kawasaki, Chi Ma, Naoya Sakamoto, Jia-Ni Chen, Li-Xin Gu, Hisayoshi Yurimoto
    METEORITICS & PLANETARY SCIENCE 55 10 2184 - 2205 2020年10月 [査読有り]
     
    Calcium-aluminum-rich 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-mantle-rim) texture. The core is dominant in area and mainly consists of Y-rich perovskite and Zr-rich davisite, with minor refractory metal nuggets, Zr,Sc-rich oxide minerals (calzirtite and tazheranite), and Fe-rich 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-dominant alloy in Os,Ir-dominant alloy or are composed of Os,Ir,Ru,Fe-alloy and Fe,Ni,Ir-alloy with troilite, scheelite, gypsum, and molybdenite. The later four phases are apparently secondary minerals. The Zr,Sc,Y-rich core is surrounded by a discontinuous layer of closely intergrown hibonite and spinel. The CAIs are rimmed by Fe-rich spinel and Al-rich 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-rich 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-rich diopside are(16)O-rich (Delta O-17 similar to-22 parts per thousand) whereas perovskite and davisite are O-16-poor (Delta O-17 similar to-3 parts per thousand). Such oxygen isotope heterogeneity suggests that the UR inclusion formed in the various degrees of(16)O-rich nebular setting or was originally O-16-rich and then experienced oxygen isotope exchange with(16)O-poor fluid on the CV3 chondrite parent body.
  • Noriyuki Kawasaki, Sohei Wada, Changkun Park, Naoya Sakamoto, Hisayoshi Yurimoto
    GEOCHIMICA ET COSMOCHIMICA ACTA 279 1 - 15 2020年06月 [査読有り][通常論文]
     
    Fine-grained Ca-Al-rich inclusions (FGIs) in CV chondrites are suggested to be condensates formed directly from the solar nebular gas. Al-Mg mineral isochrons of seven FGIs from reduced CV chondrites Efremovka, Vigarano, Thiel Mountains 07007, and Northwest Africa 8613 were obtained via in situ Al-Mg isotope measurements using secondary ion mass spectrometry. The slopes of the mineral isochrons for seven FGIs exhibit statistically significant variations in initial Al-26/Al-27 ratios, (Al-26/Al-27)(0), ranging from (5.19 +/- 0.17) to (3.35 +/- 0.21) x 10(-5), which correspond to a relative age spread of 0.44 +/- 0.07 Myr. Inferred upper limit of (Al-26/Al-27)(0) for the FGIs is identical to the Solar System (Al-26/Al-27)(0) of similar to 5.2 x 10(-5) as determined by whole-rock Al-Mg isochron studies for CAIs in CV chondrites. The intercepts of the mineral isochrons, the initial Mg-26/Mg-24 ratios the FGIs formed with, are consistent with Mg-isotope evolution path of a solar-composition nebular gas. The observed variations in (Al-26/Al-27)(0) for FGIs are essentially similar to those (similar to 5.2 to similar to 4.2 x 10(-5)) for coarse-grained, igneous CAIs of CV chondrites that are formed by melting and solidification. If Al-26 was distributed homogeneously in the forming region, then our data indicate that thermal processes of condensation and melting for CAI formation occurred contemporaneously and continued for at least similar to 0.4 Myr at the very beginning of the Solar System. Alternatively, the observed variations in (Al-26/Al-27)(0) also indicate the possibility of heterogeneous distributions of Al-26 in the forming region, corresponding to a range of over at least 3.4 x 10(-5) < (Al-26/Al-27)(0) < 5.2 x 10(-5). (C) 2020 Elsevier Ltd. All rights reserved.
  • Daiki Yamamoto, Shogo Tachibana, Noriyuki Kawasaki, Hisayoshi Yurimoto
    METEORITICS & PLANETARY SCIENCE 55 6 1281 - 1292 2020年06月 [査読有り][通常論文]
     
    Oxygen isotope exchange experiments between tens of nanometer-sized amorphous enstatite grains and water vapor were carried out under a condition of protoplanetary disk-like low water vapor pressure in order to investigate the survivability of distinct oxygen isotope signatures of presolar silicate grains in the protosolar disk. Oxygen isotope exchange between amorphous enstatite and water vapor proceeded at 923-1003 K and 0.3 Pa of water vapor through diffusive isotope exchange in the amorphous structure. The rate of diffusive isotope exchange is given by D (m(2) s(-1)) = (5.0 +/- 0.2) x 10(-21) exp[-161.3 +/- 1.7 (kJ mol(-1)) R-1 (1/T-1/1200)]. The activation energy for the diffusive isotope exchange for amorphous enstatite is the same as that for amorphous forsterite within the analytical uncertainties, but the isotope exchange rate is similar to 30 times slower in amorphous enstatite because of the difference in frequency factor of the reaction. The reaction kinetics indicates that 0.1-1 mu m-sized presolar amorphous silicate dust with enstatite and forsterite compositions would avoid oxygen isotope exchange with protosolar disk water vapor only if they were kept at temperatures below similar to 500-650 K within the lifetime of the disk gas.
  • Ai-Cheng Zhang, Noriyuki Kawasaki, Minami Kuroda, Yang Li, Hua-Pei Wang, Xue-Ning Bai, Naoya Sakamoto, Qing-Zhu Yin, Hisayoshi Yurimoto
    GEOCHIMICA ET COSMOCHIMICA ACTA 275 48 - 63 2020年04月 [査読有り][通常論文]
     
    Most meteorites are believed to be chips from planetesimals and can provide clues to constrain the chemical evolution and dynamic history of the early Solar System. In this study, we report two unique fragments (ALF-1 and ALF-2) enclosed in the CH3 carbonaceous chondrite Sayh al Uhaymir 290. These two fragments are dominated by Ca,Fe-rich olivine with various amounts of Al,Ti-rich augite, anorthite, oxide minerals, Ca-phosphate mineral, FeNi metal, enstatite, and less Al,Ti-rich augite. The Ca-Mg-Fe systematics and Fe/Mn ratios of olivine grains in the two fragments are similar to that of the volcanic angrites. These similar features imply that the parent body of the two fragments might have bulk chemistry, oxygen fugacity, and differentiation resembling the angrite parent body. However, high-precision SIMS measurements reveal oxygen isotope compositions Delta O-17 = 0.91 +/- 0.18 parts per thousand (2 sigma) of olivine in the two fragments are distinctly different from that of known angrite meteorites, possibly representing a new type of basaltic planetesimal.The two fragments also have a few mineralogical features distinct from angrite meteorites. They include: (1) the lack of a typical igneous texture; (2) the coexistence of two spatially associated Al,Ti-rich augites with different contents of CaO, Al2O3, MgO, and P2O5; (3) the presence of an enstatite-dominant rim in ALF-1; (4) the presence of a Cr,Mn-rich margin in ALF-1; and (5) complex microscale heterogeneity in oxide minerals. We argue that these features could be due to complex thermal histories in their parent body and/or after ejection from their parent body. Among these features, the Mn,Cr-rich margin and the enstatite-dominant rim in ALF-1 can be best explained with thermal events in nebular settings. This implies that the differentiation of the parent body of the two fragments might have taken place prior to the dissipation of the nebular gas. (C) 2020 Elsevier Ltd. All rights reserved.
  • Ai-Cheng Zhang, Noriyuki Kawasaki, Huiming Bao, Jia Liu, Liping Qin, Minami Kuroda, Jian-Feng Gao, Li-Hui Chen, Ye He, Naoya Sakamoto, Hisayoshi Yurimoto
    NATURE COMMUNICATIONS 11 1 2020年03月 [査読有り][通常論文]
     
    Diogenites are a group of meteorites that are derived from the interior of the largest protoplanet Vesta. They provide a unique opportunity to understanding together the internal structure and dynamic evolution of this protoplanet. Northwest Africa (NWA) 8321 was suggested to be an unbrecciated noritic diogenite meteorite, which is confirmed by our oxygen and chromium isotopic data. Here, we find that olivine in this sample has been partly replaced by orthopyroxene, troilite, and minor metal. The replacement texture of olivine is unambiguous evidence of sulfur-involved metasomatism in the interior of Vesta. The presence of such replacement texture suggests that in NWA 8321, the olivine should be of xenolith origin while the noritic diogenite was derived from partial melting of pre-existing rocks and had crystallized in the interior of Vesta. The post-Rheasilvia craters in the north-polar region on Vesta could be the potential source for NWA 8321.
  • Jean Bollard, Noriyuki Kawasaki, Naoya Sakamoto, Mia Olsen, Shoichi Itoh, Kirsten Larsen, Daniel Wielandt, Martin Schiller, James N. Connelly, Hisayoshi Yurimoto, Martin Bizzarro
    GEOCHIMICA ET COSMOCHIMICA ACTA 260 62 - 83 2019年09月 [査読有り][通常論文]
     
    Chondrites are fragments of asteroids that avoided melting and, thus, provide a record of the material that accreted to form protoplanets. The dominant constituent of chondrites are millimeter-sized chondrules formed by transient heating events in the protoplanetary disk. Some chondritic components, including chondrules, contain evidence of the extinct short-lived radionuclide Al-26 (half-life of 0.73 Myr). The decay of Al-26 is postulated to have been an important heat source promoting asteroidal melting and differentiation. Thus, understanding the Al-26 inventory in the accretion regions of differentiated asteroids is critical to constrain the accretion timescales of protoplanets. The current paradigm asserts that the canonical Al-26/Al-27 ratio of similar to 5 x 10(-5) recorded by the oldest dated solids, calcium-aluminium refractory inclusions, represents that of the bulk Solar System. We report, for the first time, the Al-26-Mg-26 systematics of chondrules from the North West Africa (NWA) 5697 L 3.10 ordinary chondrite and Allende CV3(OXA) (Vigarano type) carbonaceous chondrite that have been previously dated by U-corrected Pb-Pb dating. Eight chondrules, which record absolute ages ranging from 4567.57 +/- 0.56 to 4565.84 +/- 0.72 Ma, define statistically-significant internal isochron relationships corresponding to initial (Al-26/Al-27) ([Al-26/Al-27](0)) ratios in their precursors at the time of CAI formation at 4567.3 +/- 0.16 Ma ranging from (3.92(+4.53)(-2.95)) x 10(-6) to (2.74(+1.30)(-1.09)) x 10(-5). These initial ratios are much lower than those predicted by the Pb-Pb ages, corresponding to age mismatches between the Pb-Pb and Al-26-Mg-26 systems ranging from 0.69(+0.54)(-0.44) to 2.71(+0.66)(-0.59) Myr. All chondrules record Cr-54/Cr-52 compositions indicating an origin from inner Solar System precursor material and, as such, we interpret the age mismatch to reflect a reduced initial abundance of Al-26 in the chondrule precursors, similar to that proposed for the angrite parent body. In particular, the range of [Al-26/Al-27](0) ratios essentially defines two groups, which are apparently correlated with the absolute ages of the chondrules. A first group, charactertized by chondrules with absolute Pb-Pb ages identical to CAIs, defines a mean [Al-26/Al-27](0), value of (4.75(+1.99)(-1.21)) x 10(-6) whereas a second group, with absolute ages similar to 1 Myr younger than CAIs, record a mean mean [Al-26/Al-27](0) of (1.82(+0.57)(-0.40)) x 10(-5).We interpret this systematic variability in [Al-26/Al-27](0) values as reflecting progressive inward transport and admixing of dust of solar composition and Al-26 content from the outer disk during chondrule recycling and remelting. Finally, a reduced [Al-26/Al-27](0) ratio in chondrule precursors impacts our understanding of the accretion timescales of differentiated planetesimals if chondrules are indeed representative of inner disk material. Using the average [Al-26/Al-27](0) ratio of (1.36 +/- 0.72) x 10(-5) defined by the eight chondrules, thermal modelling constrains the accretion of differentiated planetesimals formed with this Al-26 inventory from similar to 0.1 to similar to 0.9 Myr after Solar System formation to ensure melting by Al-26 decay. (C) 2019 The Authors. Published by Elsevier Ltd.
  • May Sas, Noriyuki Kawasaki, Naoya Sakamoto, Phil Shane, Georg F. Zellmer, Adam J. R. Kent, Hisayoshi Yurimoto
    CHEMICAL GEOLOGY 513 153 - 166 2019年05月 [査読有り][通常論文]
     
    We investigated the potential of multi-collector secondary ion mass spectrometry (MC-SIMS) as a tool for obtaining Sr isotopic compositions in plagioclase, a ubiquitous mineral in igneous rocks that serves as a recorder of crystallization history. MC-SIMS allows for high spatial resolution analysis (similar to 12 mu m in this study) of isotopes, and therefore improves the temporal scale at which fluctuations in crystallization conditions can be recognized, ultimately improving our understanding of rates of magmatic processes. Plagioclase crystals from two young rhyolitic deposits from two major eruptive complexes, Tarawera and Haroharo, of the Okataina Volcanic Centre in New Zealand were analysed. Results were corrected for matrix effects using linear modelling of MC-SIMS data versus An contents, as well as Sr-87/Sr-86 ratios acquired via laser ablation inductively-coupled plasma mass spectrometry (LA-MC-ICP-MS). Corrected MC-SIMS Sr isotopic ratios had an average 2 sigma uncertainty of +/- 0.0008 per spot, and were homogeneous in Okataina plagioclase at high spatial resolutions. Average LA-MC-ICP-MS Sr-87/Sr-86 ratios of plagioclase from both intra-caldera volcanic complexes (Tarawera Sr-87/Sr-86 = 0.7056 and Haroharo Sr-87/Sr-86 = 0.7054) suggest similar magma sources and similar assimilation and fractional crystallization processes for the two complexes. Overall homogeneity of plagioclase (excluding relict cores) indicates no significant changes in contributions (i.e., crustal assimilation, mafic influx) to the system during the majority of plagioclase crystal growth. Furthermore, lack of Sr-87/Sr-86 ratio fluctuations in plagioclase rims suggest interaction between the resident silicic magma and the intruding mafic magma that triggered the eruptions was largely limited to volatile and heat transfer. Using appropriate standards and analysis, this MC-SIMS method can be used to detect short-lived, open-system events in magma reservoirs where differences in Sr-87/Sr-86 isotopic ratios are significant.
  • Noriyuki Kawasaki, Changkun Park, Naoya Sakamoto, Sun Young Park, Hyun Na Kim, Minami Kuroda, Hisayoshi Yurimoto
    EARTH AND PLANETARY SCIENCE LETTERS 511 25 - 35 2019年04月 [査読有り][通常論文]
     
    Al-Mg mineral isochrons of three Ca-Al-rich inclusions (CAIs) that formed primarily by condensation, one fine-grained, spinel-rich inclusion and two fluffy Type A CAIs, from the reduced CV chondrites Efremovka and Vigarano were obtained by in situ Al-Mg isotope measurements using secondary ion mass spectrometry. The slope of the isochron obtained for the fine-grained, spinel-rich inclusion gives an initial Al-26/Al-27 value, (Al-26/Al-27)(0), of (5.19 +/- 0.17) x 10(-5). This is essentially identical to the Solar System initial Al-26/Al-27 determined by whole-rock Al-Mg isochron studies for CAIs in CV chondrites. In contrast, the isochron slopes for the two fluffy Type A CAIs from their Al-Mg mineral isochrons, (4.703 +/- 0.082) x 10(-5) and (4.393 +/- 0.084) x 10(-5), are significantly lower than the Solar System initial value. The range of (Al-26/Al-27)(0) values of the three CAIs, from (5.19 +/- 0.17) to (4.393 +/- 0.084) x 10(-5), corresponds to a formation age spread of 0.17 +/- 0.04 Myr. This formation age spread is similar to that of igneous CAIs from CV chondrites. The data suggest that condensation and melting of minerals occurred in the hot nebular gas contemporaneously for similar to 0.2 Myr at the very beginning of our Solar System, if Al-26 was distributed homogeneously in the CAI forming region. Alternatively, the observed variations in (Al-26/Al-27)(0) among fluffy Type A CAIs would also raise a possibility of heterogeneous distributions of Al-26 in the forming region. (C) 2019 Elsevier B.V. All rights reserved.
  • Noriyuki Kawasaki, Steven B. Simon, Lawrence Grossman, Naoya Sakamoto, Hisayoshi Yurimoto
    GEOCHIMICA ET COSMOCHIMICA ACTA 221 318 - 341 2018年01月 [査読有り][通常論文]
     
    TS34 is a Type B1 Ca-Al-rich inclusion (CAI) from the Allende CV3 chondrite, consisting of spinel, melilite, Ti-Al-rich clinopyroxene (fassaite) and minor anorthite in an igneous texture. Oxygen and magnesium isotopic compositions were measured by secondary ion mass spectrometry in spots of known chemical composition in all major minerals in TS34. Using the sequence of formation from dynamic crystallization experiments and from chemical compositions of melilite and fassaite, the oxygen isotopic evolution of the CAI melt was established. Oxygen isotopic compositions of the constituent minerals plot along the carbonaceous chondrite anhydrous mineral line. The spinel grains are uniformly O-16-rich (Delta O-17= -22.7 +/- 1.7%, 2SD), while the melilite grains are uniformly O-16-poor (Delta O-17= -2.8 +/- 1.8 parts per thousand) irrespective of their akermanite content and thus their relative time of crystallization. The fassaite crystals exhibit growth zoning overprinting poorly-developed sector zoning; they generally grow from Ti-rich to Ti-poor compositions. The fassaite crystals also show continuous variations in Delta O-17 along the inferred directions of crystal growth, from 16O-poor (Delta O-17 similar to-3 parts per thousand) to O-16-rich (Delta O-17 similar to-23 parts per thousand), covering the full range of oxygen isotopic compositions observed in TS34. The early-crystallized O-16-poor fassaite and the melilite are in oxygen isotope equilibrium and formed simultaneously. The correlation of oxygen isotopic compositions with Ti content in the fassaite imply that the oxygen isotopic composition of the CAI melt evolved from O-16-poor to O-16-rich during fassaite crystallization, presumably due to oxygen isotope exchange with a surrounding O-16-rich nebular gas. Formation of spinel, the liquidus phase in melts of this composition, predates crystallization of all other phases, so its O-16-rich composition is a relic of an earlier stage. Anorthite exhibits oxygen isotopic compositions between Delta O-17 similar to-2 parts per thousand and -9 parts per thousand, within the range of those of fassaite, indicating co-crystallization of these two minerals during the earliest to intermediate stage of fassaite growth. The melilite and fassaite yield an Al-26-Mg-26 mineral isochron with an initial value of (Al-26/Al-27)(0) = (5.003 +/- 0.075) x 10(-5), corresponding to a relative age of 0.05 +/- 0.02 Myr from the canonical Al-Mg age of CAIs. These data demonstrate that both O-16-rich and O-16-poor reservoirs existed in the solar nebula at least similar to 0.05 Myr after the birth of the Solar System. (C) 2017 The Author(s). Published by Elsevier Ltd.
  • Noriyuki Kawasaki, Shoichi Itoh, Naoya Sakamoto, Hisayoshi Yurimoto
    GEOCHIMICA ET COSMOCHIMICA ACTA 201 201 83 - 102 2017年03月 [査読有り][通常論文]
     
    Fluffy Type A Ca-Al-rich inclusions (CAIs) containing reversely zoned melilite crystals are suggested to be aggregates of direct condensates from solar nebular gas. We conducted an investigation of Al-26-Mg-26 systematics of a fluffy Type A CAI from Vigarano, named V2-01, with known oxygen isotopic distributions of reversely zoned melilite crystals; we also conducted oxygen isotope measurements of coexisting minerals. Two of six reversely zoned melilite crystals show continuous variations in magnesium isotopic composition, with delta Mg-25 decreasing along the inferred direction of crystal growth, which supports the idea that they originated through condensation. Petrography suggests that the constituent minerals of V2-01 formed in the following order: first spinel and fassaite enclosed by melilite, then reversely zoned melilite crystals, and spinel and diopside in the Wark-Lovering rim. The spinel enclosed by melilite has O-16-rich compositions (Delta O-17 similar to -24 parts per thousand) and on an Al-Mg evolutionary diagram plots along model isochron with an initial value of (Al-26/Al-27)(0) = (5.6 +/- 0.2) X 10(-5). The fassaite enclosed by melilite crystals shows variable oxygen isotopic compositions (Delta O-17 similar to -12 parts per thousand and -17 parts per thousand) and plots on an isochron with (Al-26/Al-27)(0) = (5.6 +/- 0.2) X 10(-5). The oxygen isotopic compositions of reversely zoned melilite showed continuous variations in Delta O-17 along the inferred direction of crystal growth, suggesting that surrounding nebular gas, during the formation of the reversely zoned melilite, changed from O-16-poor (Delta O-17 values larger than -10 parts per thousand) to O-16-rich (Delta 17 O similar to -25 parts per thousand). The six reversely zoned melilite crystals show indistinguishable initial Al-26/Al-27 values with an average (Al-26/Al-27)(0) of (4.7 +/- 0.3) X 10(-5), which is clearly distinguishable from the value of enclosed spinel and fassaite, indicating a younger formation age than the enclosed spinel and fassaite. The spinel and diopside from the Wark-Lovering rim show O-16-rich compositions (Delta O-17 similar to -23 parts per thousand) with (Al-26/Al-27)(0) = (4.5 +/- 0.4) X 10(-5). The values of (Al-26/Al-27)(0) are consistent with the formation sequence inferred from petrography. The formation period for the V2-01 CAI is estimated to be 0.18 +/- 0.07 Myr from the difference in initial (Al-26/Al-27) values. These data suggest that the oxygen isotopic composition of solar nebular gas surrounding the CAI changed from O-16-rich to O-16-poor and back to O-16-rich during the first similar to 0.2 Myr of Solar System formation. (C) 2016 Elsevier Ltd. All rights reserved.
  • Noriyuki Kawasaki, Chizu Kato, Shoichi Itoh, Shigeyuki Wakaki, Motoo Ito, Hisayoshi Yurimoto
    GEOCHIMICA ET COSMOCHIMICA ACTA 169 99 - 114 2015年11月 [査読有り][通常論文]
     
    Disequilibrium oxygen isotopic distributions of Ca-Al-rich inclusions (CAIs) correspond to multiple melting events in the solar nebula. Al-26-Mg-26 systematics may be applicable for age differences among such melting events. We have carried out a coordinated study of detailed petrographic observations and in-situ oxygen and magnesium isotope measurements for a Type C CAI, EK1-04-2, from the Allende CV3 meteorite to determine the melting events and their ages. The CAI consists mainly of spinel, anorthite, olivine, and pyroxene, and has a core and mantle structure. Petrography of the core suggests that the crystallization sequence of the core minerals is from spinel, anorthite, olivine, and to pyroxene. The mantle has the same mineral assemblage as the core, and shows incomplete melting and solidification textures. Oxygen isotopic compositions of the minerals are distributed along the carbonaceous chondrite anhydrous mineral (CCAM) line (delta O-18 = -44 parts per thousand to +9 parts per thousand), which indicates to preserve a chemical disequilibrium status in the CAI. Spinel shows a O-16-rich signature (delta O-18 similar to -43 parts per thousand), while anorthite is O-16-poor (delta O-18 similar to+8 parts per thousand). Olivine and pyroxene in the core have the same oxygen isotopic composition (delta O-18 similar to-15 parts per thousand), which indicates their equilibrium. Olivine and pyroxene in the mantle have variable oxygen isotopic compositions and are slightly depleted in O-16 (delta O-18 = -13 parts per thousand to -4 parts per thousand) compared with the same minerals in the core. The Al-26-Mg-26 systematics is consistent with the disequilibrium status observed according to the petrography and oxygen isotopes. Spinel is plotted on a line of (Al-26/Al-27)(0) = (3.5 +/- 0.2) x 10(-5), anorthite is plotted on a line of (-1 +/- 5) x 10(-7), and olivine and pyroxene in the core are plotted on a line of (-1 +/- 7)x 10(-6). Plots of olivine and pyroxene in the mantle are scattered below the isochron of these minerals in the core. This study indicates that the EK1-04-2 Type C CAI underwent multiple heating events after the formation of its CAI precursor. The precursor CAI was formed similar to 0.4 Myr after the formation of the Solar System defined by canonical CAI formation. At least 1.6 Myr after the precursor CAI formation, the CAI was partially melted and the melt exchanged oxygen isotopes with surrounding O-16-poor nebular gas. O-16-poor olivine and pyroxene in the core crystallized from the melt. Subsequently, Al-rich chondrules accreted onto the CAI, and the CAI experienced partial melting again and recrystallized to form the mantle. The oxygen and magnesium isotopes in anorthite were redistributed during thermal metamorphism in the Allende parent body. Our study reveals that the CAI had been retained in the solar nebula for at least 1.6 Myr and underwent multiple melting events in the nebula, and oxygen and Al-26-Mg-26 systematics has been partially disturbed depending on crystal sizes by metamorphism on the parent body. (C) 2015 Elsevier Ltd. All rights reserved.
  • Takuo Okuchi, Narangoo Purevjav, Naotaka Tomioka, Jung-Fu Lin, Takahiro Kuribayashi, Louise Schoneveld, Huijeong Hwang, Naoya Sakamoto, Noriyuki Kawasaki, Hisayoshi Yurimoto
    AMERICAN MINERALOGIST 100 7 1483 - 1492 2015年07月 [査読有り][通常論文]
     
    The presence of water in the Earth's deep mantle is an issue of increasing interest in the field of high-pressure mineralogy. An important task for further advancing research in the field is to create homogeneous single crystals of candidate deep-mantle water-bearing minerals of 1 mm or larger in size, which is required for applying them for the time-of-flight (TOE) single-crystal Laue diffraction method with a third-generation neutron instrument. In this study, we perform several experiments to demonstrate an improved methodology for growing hydrous crystals of such large sizes at relevant transition zone and lower-mantle conditions via very slow cooling over a maximum period of 1 day. Successfully synthesized crystals using this methodology include dense hydrous magnesium silicate (DHMS) phase E, hydrous wadsleyite, hydrous ringwoodite, and bridgmanite (silicate perovskite). It is also demonstrated that these hydrous crystals can be grown from deuterium enriched starting materials in addition to those having a natural hydrogen isotope ratio.Magnitudes of chemical and crystallographic heterogeneities of the product crystals were characterized by comprehensive analysis of X-ray precession photography, single-crystal X-ray diffraction (SCXRD), field-emission scanning electron microscope (FE-SEM), electron probe microanalyzer (EPMA), secondary ion mass spectroscopy (SIMS)(,) powder X-ray diffraction (PXRD), and TOF neutron powder diffraction (TOF-NPD). The product crystals were confirmed to be inclusion free and crystallographically homogeneous. Compositional and isotopic differences of major elements and hydrogen isotope abundances were lower than 1 and 3%, respectively, among intracrystals and intercrystals within each recovered sample capsule. Phase E crystals up to 600 mu m in the largest dimension were grown at a constant temperature of 1100 degrees C kept for 3 h. Using a lattice parameter-to-temperature relation of phase E, the thermal gradient in the sample capsules for the phase E synthesis has been evaluated to be 20 degrees C/mm. Hydrous wadsleyite crystals up to 1100 gm in the largest dimension were grown at 1390 degrees C with a temperature reduction of 70 degrees C during heating for 10 h. Hydrous ringwoodite crystals up to 1000 mu m in the largest dimension were grown at around 1400 degrees C with a temperature reduction of 110 degrees C during heating for 12 h. Bridgmanite crystals up to 600 mu m in the largest dimension were grown at 1700 degrees C with a temperature reduction of 30 degrees C during heating for 12 h. A TOF single-crystal diffraction instrument has been successfully used for analyzing one of the hydrous wadsleyite crystals, which demonstrated that single crystals appropriate for their expected usage are created using the method proposed in the present study.
  • Noriyuki Kawasaki, Naoya Sakamoto, Hisayoshi Yurimoto
    METEORITICS & PLANETARY SCIENCE 47 12 2084 - 2093 2012年12月 [査読有り][通常論文]
     
    Different oxygen isotopic reservoirs have been recognized in the early solar system. Fluffy type A Ca-Al-rich inclusions (CAIs) are believed to be direct condensates from a solar nebular gas, and therefore, have acquired oxygen from the solar nebula. Oxygen isotopic and chemical compositions of melilite crystals in a type A CAI from Efremovka CV3 chondrite were measured to reveal the temporal variation in oxygen isotopic composition of surrounding nebular gas during CAI formation. The CAI is constructed of two domains, each of which has a core-mantle structure. Reversely zoned melilite crystals were observed in both domains. Melilite crystals in one domain have a homogeneous 16O-poor composition on the carbonaceous chondrite anhydrous mineral (CCAM) line of delta 18O = 510 parts per thousand, which suggests that the domain was formed in a 16O-poor oxygen isotope reservoir of the solar nebula. In contrast, melilite crystals in the other domain have continuous variations in oxygen isotopic composition from 16O-rich (delta 18O = -40 parts per thousand) to 16O-poor (delta 18O = 0 parts per thousand) along the CCAM line. The oxygen isotopic composition tends to be more 16O-rich toward the domain rim, which suggests that the domain was formed in a variable oxygen isotope reservoir of the solar nebula. Each domain of the type A CAI has grown in distinct oxygen isotope reservoir of the solar nebula. After the domain formation, domains were accumulated together in the solar nebula to form a type A CAI.
  • Hisayoshi Yurimoto, Ken-ichi Abe, Masanao Abe, Mitsuru Ebihara, Akio Fujimura, Minako Hashiguchi, Ko Hashizume, Trevor R. Ireland, Shoichi Itoh, Juri Katayama, Chizu Kato, Junichiro Kawaguchi, Noriyuki Kawasaki, Fumio Kitajima, Sachio Kobayashi, Tatsuji Meike, Toshifumi Mukai, Keisuke Nagao, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Changkun Park, Naoya Sakamoto, Yusuke Seto, Masashi Takei, Akira Tsuchiyama, Masayuki Uesugi, Shigeyuki Wakaki, Toru Yada, Kosuke Yamamoto, Makoto Yoshikawa, Michael E. Zolensky
    SCIENCE 333 6046 1116 - 1119 2011年08月 [査読有り][通常論文]
     
    Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in O-16 relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid.

その他活動・業績

受賞

  • 2021年 日本地球化学会奨励賞

共同研究・競争的資金等の研究課題

  • 微惑星における水の活動時期の年代測定
    日本学術振興会：科学研究費助成事業 挑戦的研究(萌芽)
    研究期間 : 2022年06月 -2025年03月 
    代表者 : 川崎 教行
  • 初期太陽系における微惑星の形成年代の測定
    山田科学振興財団：研究援助
    研究期間 : 2022年08月 -2024年03月
  • 小惑星リュウグウの進化史の解明
    北海道科学技術総合振興センター ノーステック財団：若手研究人材・ネットワーク育成補助金（ノースタレント補助金）
    研究期間 : 2022年08月 -2023年03月
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2020年04月 -2023年03月 
    代表者 : 馬上 謙一, 川崎 教行
     
    プレソーラー炭化ケイ素(SiC)は炭素星やAGB星の星周で形成したと考えられている. これらの星では太陽系とは異なる核反応が進行しているため，太陽系とは異なる同位体組成を持つ．またこれらの星周で形成したSiCは高エネルギー粒子を含む恒星風や星間での銀河宇宙線が照射されていると考えられる．SiCに残されている恒星風起源希ガスの深さ方向のプロファイルは恒星風のエネルギーを反映していると考えられる．本研究では同位体ナノスコープを用いたプレソーラーSiC中のHe測定を行い，深さ方向の分布を測定した． プレソーラーSiCはMurchison 隕石から抽出したKJGグループを用いた． SiCスタンダード基盤を用いて，He-4， C-12，13， Si-28, 29, 30が定量できるような同位体ナノスコープの分析条件を確立した．そして，KJG粒子の深さ方向分析によってHe-4の深さ方向の分布を見積もることができた．KJGのHe-4深さ方向分析の結果，主要元素であるSiとCはスタンダードと同様のイオン強度が一定なプロファイルが得られた．そして， He-4もKJGから検出され，更に，深さ方向に分布が見られた．これは恒星風がHeイオン注入されていることを示唆しており，初めて実験的に太陽系外の恒星風を検証する手法を提示することができた． 現在の同位体ナノスコープでの炭素・シリコン同位体比測定精度はプレソーラーSiCが持っている同位体異常と同程度であることがわかった．SiとCの同位体は，SiCが形成した恒星の化学組成や大きさに依存しているため，SiCの形成環境を知る重要な手掛かりとなる．そのため，SiCの起源決定には，CAMECA ims-1280HR を用いた高精度Si，C同位体比測定を行うことにした．
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2019年04月 -2023年03月 
    代表者 : 橘 省吾, 瀧川 晶, 川崎 教行, 圦本 尚義
     
    本研究では「太陽型ダスト」から「地球型ダスト」への星間ダストの変身を担った太陽系最初期の化学過程(地球型ダストの誕生)に注目し，太陽系最初期のケイ酸塩・酸化物ダストとガス（H2O, CO）との酸素同位体交換反応の速度やメカニズムを実験で決定し，酸素同位体交換に必要な原始惑星系円盤の物理化学条件を定量的に決定する．また，酸素同位体交換反応によって，酸素同位体組成は地球型になったが，金属元素同位体組成は恒星周ダストのままである（円盤ガス中の金属元素存在度は低く，同位体交換が進まない）太陽系原材料ダストを始原隕石中に発見し，初期太陽系での酸素同位体交換反応による地球型ダスト誕生過程の証明をめざす（これまでの分析手法では，発見が困難であった）．今年度は，FeOを含むかんらん石組成の非晶質ケイ酸塩の結晶化速度の決定に加え，酸素同位体交換速度の推定をおこなった．FeOを含むかんらん石組成の非晶質ケイ酸塩の結晶化速度は，FeOを含まないかんらん石組成の非晶質ケイ酸塩に比べ，3-4桁結晶化速度が速いが，酸素同位体交換速度は一桁程度しか速くないことが予察的結果として，得られた．この結果はFeOを含むかんらん石組成の非晶質ケイ酸塩は原始惑星系円盤で結晶化が速やかに起こり，酸素同位体交換が十分に起きない可能性を示す．すなわち，このような組成のダストが初期太陽系には存在しなかった（非晶質ケイ酸塩への鉄の混入は小天体形成後に起きた）ことを示唆する．酸素同位体交換速度の決定を今後進める．また，一酸化炭素と非晶質ケイ酸塩との酸素同位体交換実験，非晶質アルミナと水蒸気の酸素同位体交換実験も進めた．
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2018年04月 -2020年03月 
    代表者 : 川崎 教行
     
    初期太陽系円盤の高温のガスから凝縮したダストの形成年代を系統的に測定し，その分布を明らかにすることが研究の目的である。始原的なコンドライト隕石に含まれる細粒CAI（Ca-Al-rich inclusion）は，約1700-1400 Kの太陽組成ガスから凝縮した鉱物の集合体であるといわれている。本研究では，始原的なコンドライト隕石である，CV3 reducedコンドライト中の細粒CAIのAl-Mg形成年代を，二次イオン質量分析法による局所同位体分析で系統的に測定する。本年度は以下の研究成果が得られた。 1. 走査電子顕微鏡を用いて，CV3 reducedコンドライト隕石から，Al-Mg形成年代を測定可能な細粒CAIを8つ見繕った。 2. 二次イオン質量分析計の光学系の調整を見直すことで，Al-Mg形成年代測定時における二次イオンの透過効率を，これまで（Kawasaki et al., 2018, GCA）の約2倍に向上させた。これにより細粒CAI中の微小鉱物結晶の年代測定が可能となった。 3. 見繕った8つの細粒CAIのうち，5つの細粒CAIのAl-Mg形成年代の測定を完了した。測定は北海道大学のマルチコレクター型質量分析計（Cameca ims-1280HR）を用いて行った。それぞれの細粒CAIについて得られたAl-Mg鉱物アイソクロンの傾きから，初生26Al/27Al比が得られ，(5.19 ± 0.17) × 10^-5から (3.35 ± 0.21) × 10^-5の広がりを示すことがわかった。この初生26Al/27Al比の広がりは，44 ± 7万年の形成年代幅に相当する。本研究により得られた細粒CAIの初生26Al/27Al比の広がりは，初期太陽系円盤の高温のガスからのダストの高温凝縮プロセスが，太陽系形成最初期の少なくとも約40万年間続いていたことを示す。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2016年04月 -2018年03月 
    代表者 : 川崎 教行
     
    本研究は，隕石中の難揮発性包有物CAIの形成年代の精密測定から，初期太陽系円盤の高温環境における，CAIダスト凝縮プロセスの継続期間を明らかにした。三つの高温凝縮物CAIの形成年代に成功し，一つは太陽系誕生時（±5万年）に形成したものであったが，他二つは，その10±4万年後と17±4万年後に，それぞれ形成したものであった。高温凝縮物CAIの中で，太陽系誕生時と有意に異なる形成年代をもつものが初めて発見された。本研究により，初期太陽系円盤において，ダスト凝縮プロセスと溶融プロセスが，太陽系誕生から少なくとも約20万年間，同時に起き続けていたことが示唆された。
  • 日本学術振興会：科学研究費助成事業
    研究期間 : 2014年04月 -2016年03月 
    代表者 : 川﨑 教行
     
    26Alは半減期約70万年で26Mgへと放射壊変する短寿命放射性核種である。初期太陽系において26Alが存在していた証拠が隕石中のCAIやコンドリュールなどから発見されたが，その起源はよくわかっていない。同じようなPb-Pb形成年代をもつCAIとコンドリュールが，それぞれ異なる初生26Al量をもつことを，前年度までの研究で明らかとなった。これにより，初期太陽系円盤内における26Al量の不均一分布が示された。本年度，形成時の26Al量が我々により測定済みであるコンドリュールの，TIMSを用いたPb-Pb年代測定が共同研究者らにより引続き行われた。得られたPb-Pb年代を用いて，コンドリュール前駆物質の26Al量を見積もると，初生26Al/27Al同位体比が比較的高い集団と低い集団とに大別された。コンドリュール形成領域内においても，26Al量が不均一であることがわかり，26Alの起源研究に一石を投じる結果となった。 本年度は並行して，SIMSによるCAIのAl-Mg年代測定を行った。初期太陽系星雲の最内縁部とされるCAI形成領域では，26Al量が均一であったことがこれまでに示されている。年代測定の結果，アエンデ隕石のType C CAIは，太陽系誕生から200万年後以上後に加熱により再溶融し，ヴィガラノ隕石産fluffy Type A CAIは，約20万年かけて凝縮・集積を経て形成，アエンデ隕石産Type B1 CAIは，太陽系誕生から約5万年後に加熱により再溶融していたことがそれぞれわかった。後者二つのCAIの酸素同位体組成を同じくSIMSにより分析した結果，太陽系誕生から，少なくとも，5から20万年の間，CAIダスト周囲のガスの酸素同位体組成が，太陽に近い組成と地球に近い組成との間で，何度も入れ替わり変化していたことが明らかとなった。

教育活動情報

主要な担当授業

  • 地球惑星科学実験Ⅲ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 時系列解析，インバージョン，数値計算，同位体，環境化学，分析化学，電子顕微鏡，隕石，結晶成長，地質温度・圧力計，海洋プレートの沈み込み，付加体，褶曲・断層の形成，マグマ，相転移，結晶学，X線回折，鉱物合成
  • 地球惑星科学実験Ⅰ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 地球惑星固体物質、偏光顕微鏡、岩石学、鉱物学、火成岩、堆積岩、隕石
  • 地球惑星科学Ⅱ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 宇宙，惑星，大気と海洋の運動と構造，気候変動，地球環境

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