2016年10月, Outstanding Contribution in Reviewing, Geochimica et Cosmochimica Acta, Geochimica et Cosmochimica Acta
学会誌・学術雑誌による顕彰

2016年08月, 茨城大学学長学術表彰「奨励賞」, 茨城大学
その他の賞

2015年09月, 日本地球化学会 奨励賞, 日本地球化学会
国内学会・会議・シンポジウム等の賞

2012年03月, 東京大学 大学院理学系研究科 研究奨励賞（博士）, 東京大学 大学院理学系研究科
その他の賞

2011年10月, 日本惑星科学会 最優秀発表賞, 日本惑星科学会
国内学会・会議・シンポジウム等の賞

2010年12月, 質量分析学会同位体比部会 最優秀口頭発表賞, 質量分析学会同位体比部会
国内学会・会議・シンポジウム等の賞

Low-Temperature Aqueous Alteration of Chondrites
Martin R. Lee; Conel M. O’D. Alexander; Addi Bischoff; Adrian J. Brearley; Elena Dobrică; Wataru Fujiya; Corentin Le Guillou; Ashley J. King; Elishevah van Kooten; Alexander N. Krot; Jan Leitner; Yves Marrocchi; Markus Patzek; Michail I. Petaev; Laurette Piani; Olga Pravdivtseva; Laurent Remusat; Myriam Telus; Akira Tsuchiyama; Lionel G. Vacher, Abstract

Chondritic meteorites (chondrites) contain evidence for the interaction of liquid water with the interiors of small bodies early in Solar System history. Here we review the processes, products and timings of the low-temperature aqueous alteration reactions in CR, CM, CI and ungrouped carbonaceous chondrites, the asteroids Ryugu and Bennu, and hydrated dark clasts in different types of meteorites. We first consider the nature of chondritic lithologies and the insights that they provide into alteration conditions, subdivided by the mineralogy and petrology of hydrated chondrites, the mineralogy of hydrated dark clasts, the effects of alteration on presolar grains, and the evolution of organic matter. We then describe the properties of the aqueous fluids and how they reacted with accreted material as revealed by physicochemical modelling and hydrothermal experiments, the analysis of fluid inclusions in aqueously formed minerals, and isotope tracers. Lastly, we outline the chronology of aqueous alteration reactions as determined using the ⁵³Mn-⁵³Cr and ¹²⁹I-¹²⁹Xe systems., Springer Science and Business Media LLC
Space Science Reviews, 2025年02月04日, ［査読有り］

Metasomatic Alteration of Type 3 Ordinary and Carbonaceous Chondrites
A. N. Krot; M. I. Petaev; L. Piani; Y. Marrocchi; W. Fujiya; O. V. Pravdivtseva; E. Dobrică; L. G. Vacher; A. J. King; M. Lee; E. Van Kooten; B. Jacobsen; C. M. O’D. Alexander; A. Bischoff; A. J. Brearley; C. Le Guillou; L. Remusat; J. Leitner; G. R. Huss, Abstract

Metasomatism refers to the process during which a pre-existing rock undergoes compositional and mineralogical transformations associated with chemical reactions triggered by the reaction of fluids which invade the protolith. It changes chemical compositions of minerals, promotes their dissolution and precipitation of new minerals. In this paper, we review metasomatic alteration of type 3 ordinary (H, L, LL) and carbonaceous (CV, CO, CK) chondrites, including (i) secondary mineralization, (ii) physicochemical conditions, (iii) chronology (⁵³Mn-⁵³Cr, ²⁶Al-²⁶Mg, ¹²⁹I-¹²⁹Xe) of metasomatic alteration, (iv) records of metasomatic alteration in H, O, N, C, S, and Cl isotopic systematics, (v) effects of metasomatic alteration on O- and Al-Mg-isotope systematics of primary minerals in chondrules and refractory inclusions, and (vi) sources of water ices in metasomatically altered CV, CO, and ordinary chondrites, and outline future studies., Springer Science and Business Media LLC
Space Science Reviews, 2025年01月20日, ［査読有り］

Thermal metamorphism and volatile evolution in unequilibrated ordinary chondrites: Implications for the delivery of hydrogen to terrestrial planets
L.G. Vacher; J. Eschrig; L. Bonal; W. Fujiya; L. Flandinet; P. Beck, Elsevier BV
Geochimica et Cosmochimica Acta, 2024年12月, ［査読有り］

Zirconium isotope composition indicates s‐process depletion in samples returned from asteroid Ryugu
Maria Schönbächler; Manuela A. Fehr; Tetsuya Yokoyama; Ikshu Gautam; Nao Nakanishi; Yoshinari Abe; Jérôme Aléon; Conel 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; Makiko K. Haba; 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; 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; 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, Abstract

Nucleosynthetic isotope variations are powerful tracers to determine genetic relationships between meteorites and planetary bodies. They can help to link material collected by space missions to known meteorite groups. The Hayabusa 2 mission returned samples from the Cb‐type asteroid (162173) Ryugu. The mineralogical, chemical, and isotopic characteristics of these samples show strong similarities to carbonaceous chondrites and in particular CI chondrites. The nucleosynthetic isotope compositions of Ryugu overlap with CI chondrites for several elements (e.g., Cr, Ti, Fe, and Zn). In contrast to these isotopes, which are of predominately supernovae origin, s‐process variations in Mo isotope data are similar to those of carbonaceous chondrites, but even more s‐process depleted. To further constrain the origin of this depletion and test whether this signature is also present for other s‐process elements, we report Zr isotope compositions for three bulk Ryugu samples (A0106, A0106‐A0107, C0108) collected from the Hayabusa 2 mission. The data are complemented with that of terrestrial rock reference materials, eucrites, and carbonaceous chondrites. The Ryugu samples are characterized by distinct ⁹⁶Zr enrichment relative to Earth, indicative of a s‐process depletion. Such depletion is also observed for carbonaceous chondrites and eucrites, in line with previous Zr isotope work, but it is more extreme in Ryugu, as observed for Mo isotopes. Since s‐process Zr and Mo are coupled in mainstream SiC grains, these distinct s‐process variations might be due to SiC grain depletion in the analyzed materials, potentially caused by incomplete sample digestion, because the Ryugu samples were dissolved on a hotplate only to avoid high blank levels for other elements (e.g., Cr). However, local depletion of SiC grains cannot be excluded. An alternative, equally possible scenario is that aqueous alteration redistributed anomalous, s‐process‐depleted, Zr on a local scale, for example, into Ca‐phosphates or phyllosilicates., Wiley
Meteoritics & Planetary Science, 2024年11月25日, ［査読有り］

Update on the 53Mn-53Cr ages of dolomite in the Ivuna CI chondrite and asteroid Ryugu sample
Shingo Sugawara; Wataru Fujiya; Noriyuki Kawasaki; Naoya Sakamoto; Akira Yamaguchi; Hisayoshi Yurimoto, 責任著者, Elsevier BV
Geochimica et Cosmochimica Acta, 2024年10月, ［査読有り］

The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites
Fridolin Spitzer; Thorsten Kleine; Christoph Burkhardt; Timo Hopp; 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; Kouki Kitajima; Shintaro Komatani; Alexander N. Krot; Ming-Chang Liu; Yuki Masuda; Mayu Morita; Fréderic Moynier; Kazuko Motomura; Izumi Nakai; Kazuhide Nagashima; 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 isotopic compositions of samples returned from Cb-type asteroid Ryugu and Ivuna-type (CI) chondrites are distinct from other carbonaceous chondrites, which has led to the suggestion that Ryugu/CI chondrites formed in a different region of the accretion disk, possibly around the orbits of Uranus and Neptune. We show that, like for Fe, Ryugu and CI chondrites also have indistinguishable Ni isotope anomalies, which differ from those of other carbonaceous chondrites. We propose that this unique Fe and Ni isotopic composition reflects different accretion efficiencies of small FeNi metal grains among the carbonaceous chondrite parent bodies. The CI chondrites incorporated these grains more efficiently, possibly because they formed at the end of the disk’s lifetime, when planetesimal formation was also triggered by photoevaporation of the disk. Isotopic variations among carbonaceous chondrites may thus reflect fractionation of distinct dust components from a common reservoir, implying CI chondrites/Ryugu may have formed in the same region of the accretion disk as other carbonaceous chondrites., American Association for the Advancement of Science (AAAS)
Science Advances, 2024年09月27日, ［査読有り］

Chondrule-like objects and a Ca-Al-rich inclusion from comets or comet-like icy bodies
Takaaki Noguchi; Daisuke Nakashima; Takayuki Ushikubo; Wataru Fujiya; Noriaki Ohashi; John P. Bradley; Tomoki Nakamura; Noriko T. Kita; Peter Hoppe; Hidemi Ishibashi; Makoto Kimura; Naoya Imae, Elsevier BV
Geochimica et Cosmochimica Acta, 2024年09月, ［査読有り］

Pyrrhotites in asteroid 162173 Ryugu: Records of the initial changes on their surfaces with aqueous alteration
Hiroharu Yui; Shu-hei Urashima; Morihiko Onose; Mayu Morita; 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, Elsevier BV
Geochimica et Cosmochimica Acta, 2024年08月, ［査読有り］

Disequilibrium oxygen isotope distribution among aqueously altered minerals in Ryugu asteroid returned samples
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, Abstract

Oxygen 3‐isotope ratios of magnetite and carbonates in aqueously altered carbonaceous chondrites provide important clues to understanding the evolution of the fluid in the asteroidal parent bodies. We conducted oxygen 3‐isotope analyses of magnetite, dolomite, and breunnerite in two sections of asteroid Ryugu returned samples, A0058 and C0002, using a secondary ion mass spectrometer (SIMS). Magnetite was analyzed by using a lower primary ion energy that reduced instrumental biases due to the crystal orientation effect. We found two groups of magnetite data identified from the SIMS pit morphologies: (1) higher δ¹⁸O (from 3‰ to 7‰) and ∆¹⁷O (~2‰) with porous SIMS pits mostly from spherulitic magnetite, and (2) lower δ¹⁸O (~ −3‰) and variable ∆¹⁷O (0‰–2‰) mostly from euhedral magnetite. Dolomite and breunnerite analyses were conducted using multi‐collection Faraday cup detectors with precisions ≤0.3‰. The instrumental bias correction was applied based on carbonate compositions in two ways, using Fe and (Fe + Mn) contents, respectively, because Ryugu dolomite contains higher amounts of Mn than the terrestrial standard. Results of dolomite and breunnerite analyses show a narrow range of ∆¹⁷O; 0.0‰–0.3‰ for dolomite in A0058 and 0.2‰–0.8‰ for dolomite and breunnerite in C0002. The majority of breunnerite, including large ≥100 μm grains, show systematically lower δ¹⁸O (~21‰) than dolomite (25‰–30‰ and 23‰–27‰ depending on the instrumental bias corrections). The equilibrium temperatures between magnetite and dolomite from the coarse‐grained lithology in A0058 are calculated to be 51 ± 11°C and 78 ± 14°C, depending on the instrumental bias correction scheme for dolomite; a reliable temperature estimate would require a Mn‐bearing dolomite standard to evaluate the instrumental bias corrections, which is not currently available. These results indicate that the oxygen isotope ratios of aqueous fluids in the Ryugu parent asteroid were isotopically heterogeneous, either spatially, or temporary. Initial water ice accreted to the Ryugu parent body might have ∆¹⁷O > 2‰ that was melted and interacted with anhydrous solids with the initial ∆¹⁷O < 0‰. In the early stage of aqueous alteration, spherulitic magnetite and calcite formed from aqueous fluid with ∆¹⁷O ~ 2‰ that was produced by isotope exchange between water (∆¹⁷O > 2‰) and anhydrous solids (∆¹⁷O < 0‰). Dolomite and breunnerite, along with some magnetite, formed at the later stage of aqueous alteration under higher water‐to‐rock ratios where the oxygen isotope ratios were nearly at equilibrium between fluid and solid phases. Including literature data, δ¹⁸O of carbonates decreased in the order calcite, dolomite, and breunnerite, suggesting that the temperature of alteration might have increased with the degree of aqueous alteration., Wiley
Meteoritics & Planetary Science, 2024年04月, ［査読有り］

Pervasive aqueous alteration in the early Solar System revealed by potassium isotopic variations in Ryugu samples and carbonaceous chondrites
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, Elsevier BV
Icarus, 2024年02月, ［査読有り］

Hydrogen in magnetite from asteroid Ryugu
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, Abstract

In order to gain insights on the conditions of aqueous alteration on asteroid Ryugu and the origin of water in the outer solar system, we developed the measurement of water content in magnetite at the micrometer scale by secondary ion mass spectrometry (NanoSIMS) and determined the H and Si content of coarse‐grained euhedral magnetite grains (polyhedral magnetite) and coarse‐grained fibrous (spherulitic) magnetite from the Ryugu polished section A0058‐C1001. The hydrogen content in magnetite ranges between ~900 and ~3300 wt ppm equivalent water and is correlated with the Si content. Polyhedral magnetite has low and homogenous silicon and water content, whereas fibrous magnetite shows correlated Si and water excesses. These excesses can be explained by the presence of hydrous Si‐rich amorphous nanoinclusions trapped during the precipitation of fibrous magnetite away from equilibrium and testify that fibrous magnetite formed from a hydrous gel with possibly more than 20 wt% water. An attempt to determine the water content in sub‐μm framboids indicates that additional calibration and contamination issues must be addressed before a safe conclusion can be drawn, but hints at elevated water content as well. The high water content in fibrous magnetite, expected to be among the first minerals to crystallize at low water–rock ratio, points to the control of water content by local conditions of magnetite precipitation rather than large‐scale alteration conditions. Systematic lithological variations associated with water‐rich and water‐poor magnetite suggest that the global context of alteration may be better understood if local water concentrations are compared with millimeter‐scale distribution of the various morphologies of magnetite. Finally, the high water content in the magnetite precursor gel indicates that the initial O isotopic composition in alteration water must not have been very different from that of the earliest magnetite crystals., Wiley
Meteoritics & Planetary Science, 2024年01月26日, ［査読有り］

Curation protocol of Phobos sample returned by Martian Moons eXploration.
Fukai R.; Usui T.; Fujiya W.; Takano Y.; Bajo K.; Beck A.; Bonato E.; Chabot M. L.; Furukawa Y.; Genda H.; Hibiya Y.; Jourdan F.; Kleine T.; Koike M.; Matsuoka M.; Miura Y. N.; Moynier F.; Okazaki R.; Russell S. S.; Sumino H.; Zolensky M. E.; Sugahara H.; Tachibana S.; Sakamoto K.; Abe M.; Cho Y. and Kuramoto K.
Meteoritics & Planetary Science, 2024年01月, ［査読有り］

Analysis of Cation Composition in Dolomites on the Intact Particles Sampled from Asteroid Ryugu
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, American Chemical Society (ACS)
Analytical Chemistry, 2023年12月29日, ［査読有り］

Neodymium‐142 deficits and samarium neutron stratigraphy of C‐type asteroid (162173) Ryugu
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, 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., Wiley
Meteoritics & Planetary Science, 2023年12月07日, ［査読有り］

Nucleosynthetic s-process depletion in Mo from Ryugu samples returned by Hayabusa2.
Nakanishi N.; Yokoyama T.; Ishikawa A.; Walker R. J.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Guntam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; Morita M.; Motomura K.; Moynier F.; Nakai I.; Nagashima K.; Nguyen A. N.; Nittler L.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Yamashita K.; Yin Q.-Z.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H.
Geochemical Perspectives Letters, 2023年12月, ［査読有り］

The magnesium isotope composition of samples returned from asteroid Ryugu.
Bizzarro M.; M. Schiller M.; Yokoyama T.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Guntam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; Morita M.; Moynier F.; Motomura K.; Nakai I.; Nagashima K.; Nesvorný D.; Nguyen A. N.; Nittler L.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H.
The Astrophysical Journal Letters, 2023年11月, ［査読有り］

Water circulation in Ryugu asteroid affected the distribution of nucleosynthetic isotope anomalies in returned sample.
Yokoyama T.; Wadhwa M.; Iizuka T.; Rai V. Guntam I.; Hibiya Y.; Masuda Y.; Haba M. K.; Fukai R.; Hines R.; Phelan N.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Ireland T. R.; Ishikawa A.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nakai I.; Nagashima K.; Nguyen A. N.; Nittler L.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H.
Science Advances, 2023年11月, ［査読有り］

The oxygen isotopic composition of samples returned from asteroid Ryugu with implications for the nature of the parent planetesimal
Tang H.; Young E. D.; Tafla L.; Park C.; Di Rocco T.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Ito M.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nagashima K.; Nakai I.; Nguyen A. N.; Nittler L.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yokoyama T.; Yoneda S.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H. (2023), We present oxygen isotopic analyses of fragments of the near-Earth C-b-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 Delta'O-17 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 Al-26, 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., IOP Publishing Ltd
The Planetary Science Journal, 2023年08月, ［査読有り］

Carbonate record of temporal change in oxygen fugacity and gaseous species in asteroid Ryugu
Fujiya W.; Kawasaki N.; Nagashima K.; Sakamoto N.; Alexander C. M. O'D.; Kita N. T.; Kitajima K.; Abe Y.; Aléon J.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Itoh S.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nakai I.; Nguyen A.; Nittler L. R.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yokoyama T.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H., 筆頭著者, The Hayabusa2 spacecraft explored asteroid Ryugu and brought its surface materials to Earth. Ryugu samples resemble Ivuna-type (CI) chondrites-the most chemically primitive meteorites-and contain secondary phyllosilicates and carbonates, which are indicative of aqueous alteration. Understanding the conditions (such as temperature, redox state and fluid composition) during aqueous alteration is crucial to elucidating how Ryugu evolved to its present state, but little is known about the temporal changes in these conditions. Here we show that calcium carbonate (calcite) grains in Ryugu and Ivuna samples have variable O-18/O-16 and C-13/C-12 ratios that are, respectively, 24-46 & PTSTHOUSND; and 65-108 & PTSTHOUSND; greater than terrestrial standard values, whereas those of calcium-magnesium carbonate (dolomite) grains are much more homogeneous, ranging within 31-36 & PTSTHOUSND; for oxygen and 67-75 & PTSTHOUSND; for carbon. We infer that the calcite precipitated first over a wide range of temperatures and oxygen partial pressures, and that the proportion of gaseous CO2/CO/CH4 molecules changed temporally. By contrast, the dolomite formed later in a more oxygen-rich and thus CO2-dominated environment when the system was approaching equilibrium. The characteristic isotopic compositions of secondary carbonates in Ryugu and Ivuna are not observed for other hydrous meteorites, suggesting a unique evolutionary pathway for their parent asteroid(s).The asteroid Ryugu experienced aqueous alteration under changing temperature and redox conditions, according to an isotopic analysis of secondary calcite and dolomite grains in samples from Ryugu obtained by the Hayabusa2 spacecraft., NATURE PORTFOLIO
Nature Geoscience, 2023年07月, ［査読有り］

Abundant presolar grains and primordial organics preserved in carbon-rich exogenous clasts in asteroid Ryugu
Nguyen A. N.; Mane P.; Keller L. P.; Piani L.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nakai I.; Nagashima K.; Nesvorný D.; Nittler L.; Onose M.; Pack A.; Park C.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yokoyama T.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H., 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 (similar to 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., AMER ASSOC ADVANCEMENT SCIENCE
Science Advances, 2023年07月, ［査読有り］

Hydrogen isotopic composition of hydrous minerals in asteroid Ryugu
Piani L.; Nagashima K.; Kawasaki N.; Sakamoto N.; Bajo K.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Itoh S.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nakai I.; Nguyen A.; Nittler L. R.; Onose M.; Pack A.; Park C.; Qin L.; Russell S. S.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yokoyama T.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H., 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/H-Ryugu, to be [165 +/- 19] x 10(-6), which corresponds to delta D-Ryugu = +59 +/- 121 parts per thousand (2 sigma). The hydrous mineral D/H-Ryugu'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 similar to 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 H-2 before being accreted on the Ryugu's parent asteroid., IOP Publishing Ltd
The Astrophysical Journal Letters, 2023年04月, ［査読有り］

Author Correction: Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis (Nature Astronomy, (2022), 7, 2, (182-189), 10.1038/s41550-022-01846-1)
Paquet, M.; Moynier, F.; Yokoyama, T.; Dai, W.; Hu, Y.; Abe, Y.; Al{\'e}on, J.; O?D. Alex; er, C.M.; Amari, S.; Amelin, Y.; Bajo, K.-I.; Bizzarro, M.; Bouvier, A.; Carlson, R.W.; Chaussidon, M.; Choi, B.-G.; Dauphas, N.; Davis, A.M.; Di Rocco, T.; Fujiya, W.; Fukai, R.; Gautam, I.; Haba, M.K.; Hibiya, Y.; Hidaka, H.; Homma, H.; Hoppe, P.; Huss, G.R.; Ichida, K.; Iizuka, T.; Irel; , T.R.; Ishikawa, A.; Ito, M.; Itoh, S.; Kawasaki, N.; Kita, N.T.; Kitajima, K.; Kleine, T.; Komatani, S.; Krot, A.N.; Liu, M.-C.; Masuda, Y.; McKeegan, K.D.; Morita, M.; Motomura, K.; Nakai, I.; Nagashima, K.; Nesvorn?, D.; Nguyen, A.N.; Nittler, L.; Onose, M.; Pack, A.; Park, C.; Piani, L.; Qin, L.; Russell, S.S.; Sakamoto, N.; Sch{\"o}nb{\"a}chler, M.; Tafla, L.; Tang, H.; Terada, K.; Terada, Y.; Usui, T.; Wada, S.; Wadhwa, M.; Walker, R.J.; Yamashita, K.; Yin, Q.-Z.; Yoneda, S.; Young, E.D.; Yui, H.; Zhang, A.-C.; Nakamura, T.; Naraoka, H.; Noguchi, T.; Okazaki, R.; Sakamoto, K.; Yabuta, H.; Abe, M.; Miyazaki, A.; Nakato, A.; Nishimura, M.; Okada, T.; Yada, T.; Yogata, K.; Nakazawa, S.; Saiki, T.; Tanaka, S.; Terui, F.; Tsuda, Y.; Watanabe, S.-I.; Yoshikawa, M.; Tachibana, S.; Yurimoto, H.
Nature Astronomy, 2023年

Oxygen isotopes of anhydrous primary minerals show kinship between asteroid Ryugu and comet 81P/Wild2.
Kawasaki N.; Nagashima K.; Sakamoto N.; Matsumoto T.; Bajo; K.; Wada S.; Igami Y.; Miyake A.; Noguchi T.; Yamamoto D.; Russell; S. S.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Ito M.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nakai I.; Nguyen A.; Nittler L. R.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yokoyama T.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H., 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: 16O-rich (associated with refractory inclusions) and 16O-poor (associated with chondrules). Both the 16O-rich and 16O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16O-rich to 16O-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.
Science Advances, 2022年12月, ［査読有り］

Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis.
Paquet M.; Moynier F.; Yokoyama T.; Dai W.; Hu Y.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Ito M.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Nakai I.; Nagashima K.; Nesvorný D.; Nguyen A.; Nittler L. R.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H., 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.
Nature Astronomy, 2022年12月, ［査読有り］

Heat-induced dolomitization of amorphous calcium magnesium carbonate (ACMC) in a CO2-filled closed System.
Sugawara S.; Fujiya W.; Kagi H.; Yamaguchi A. and Hashizume K.
ACS Omega, 2022年11月, ［査読有り］

The Solar System calcium isotopic composition inferred from Ryugu samples.
Moynier F.; Dai W.; Yokoyama T.; Hu Y; Paquet M.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Ito M.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Nakai I.; Nagashima K.; Nesvorný D.; Nguyen A.; Nittler L. R.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H., European Association of Geochemistry
Geochemical Perspectives Letters, 2022年10月, ［査読有り］

Ryugu’s nucleosynthetic heritage from the outskirts of the Solar System.
Hopp T.; Dauphas N.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Ito M.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nakai I.; Nagashima K.; Nesvorný D.; Nguyen A.; Nittler L. R.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yokoyama T.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Miyazaki A.; Nakato A.; Nishimura M.; Okada T.; Yada T.; Yogata K.; Nakazawa S.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yoshikawa M.; Tachibana S. and Yurimoto H., 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., American Association for the Advancement of Science (AAAS)
Science Advances, 2022年10月, ［査読有り］

Presolar stardust in asteroid Ryugu.
Barosch J.; Nittler L. R.; Wang J.; Alexander C. M. O'D.; De Gregorio B. T.; Engrand C.; Kebukawa Y.; Nagashima K.; Stroud R. M.; Yabuta H.; Abe Y.; Aléon J.; Amari S.; Amelin Y.; Bajo K.; Bejach L.; Bizzarro M.; Bonal L.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Cody G. D.; Dartois E.; Dauphas N.; Davis A. M.; Dazzi A.; Deniset-Besseau A.; Di Rocco T.; Duprat E.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hashiguchi M.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Ito M.; Itoh S.; Kamide K.; Kawasaki N.; Kilcoyne A. L. D.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Komatsu M.; Krot A. N.; Liu M.-C.; Martins Z.; Masuda Y.; Mathurin J.; McKeegan K. D.; Montagnac G.; Morita M.; Mostefaoui S.; Motomura K.; Moynier F.; Nakai I.; Nguyen A.; Ohigashi T.; Okumura T.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Quirico E.; Remusat L.; Russell S. S.; Sakamoto N.; Sandford S. A.; Schönbächler M.; Shigenaka M.; Suga H.; Tafla L.; Takahashi Y.; Takeichi Y.; Tamenori Y.; Tang H.; Terada K.; Terada Y.; Usui T.; Vendier-Paoletti M.; Wada S.; Wadhwa M.; Wakabayashi D.; Walker R. J.; Yamashita K.; Yamashita S.; Yin Q.-Z.; Yokoyama T.; Yoneda S.; Young E. D.; Yui H.; Zhang A.-C.; Abe M.; Miyazaki A.; Nakato A.; Nakazawa S.; Nishimura M.; Okada T.; Saiki T.; Tanaka S.; Terui F.; Tsuda Y.; Watanabe S.; Yada T.; Yogata K.; Yoshikawa M.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Tachibana S. and Yurimoto; H., Abstract

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 ${9.0}_{-3.6}^{+5.4}$ 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., American Astronomical Society
The Astrophysical Journal Letters, 2022年08月, ［査読有り］

Recent advances in our understanding of water and aqueous activity in chondrites.
Vacher L. G. and Fujiya W.
Elements, 2022年06月, ［査読有り］

Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites.
Yokoyama T.; Nagashima K.; Nakai I.; Young E. D.; Abe Y.; Aléon J.; Alexander C. M. O'D.; Amari S.; Amelin Y.; Bajo K.; Bizzarro M.; Bouvier A.; Carlson R. W.; Chaussidon M.; Choi B.-G.; Dauphas N.; Davis A. M.; Di Rocco T.; Fujiya W.; Fukai R.; Gautam I.; Haba M. K.; Hibiya Y.; Hidaka H.; Homma H.; Hoppe P.; Huss G. R.; Ichida K.; Iizuka T.; Ireland T. R.; Ishikawa A.; Ito M.; Itoh S.; Kawasaki N.; Kita N. T. Kitajima K.; Kleine T.; Komatani S.; Krot A. N.; Liu M.-C.; Masuda Y.; McKeegan K. D.; Morita M.; Motomura K.; Moynier F.; Nguyen A.; Nittler L. R.; Onose M.; Pack A.; Park C.; Piani L.; Qin L.; Russell S. S.; Sakamoto N.; Schönbächler M.; Tafla L.; Tang H.; Terada K.; Terada Y.; Usui T.; Wada S.; Wadhwa M.; Walker R. J.; Yamashita K.; Yin Q.-Z.; Yoneda S.; Yui H.; Zhang A.-C.; Connolly; H. C.; Jr. Lauretta D. S.; Nakamura T.; Naraoka H.; Noguchi T.; Okazaki R.; Sakamoto K.; Yabuta H.; Abe M.; Arakawa M.; Fujii A.; Hayakawa M.; Hirata N.; Hirata N.; Honda R.; Honda C.; Hosoda S.; Iijima Y.; Ikeda H.; Ishiguro M.; Ishihara Y.; Iwata T.; Kawahara K.; Kikuchi S.; Kitazato K.; Matsumoto K.; Matsuoka M.; Michikami T.; Mimasu Y.; Miura A.; Morota T.; Nakazawa S.; Namiki N.; Noda H.; Noguchi R.; Ogawa N.; Ogawa K.; Okada T.; Okamoto C.; Ono G.; Ozaki M.; Saiki T.; Sakatani N.; Sawada H.; Senshu H.; Shimaki Y.; Shirai K.; Sugita S.; Takei Y.; Takeuchi H.; Tanaka S.; Tatsumi E.; Terui F.; Tsuda Y.; Tsukizaki R.; Wada K.; Watanabe S.; Yamada M.; Yamada T.; Yamamoto Y.; Yano H.; Yokota Y.; Yoshihara K.; Yoshikawa M.; Yoshikawa K.; Furuya S.; Hatakeda K.; Hayashi T.; Hitomi Y.; Kumagai K.; Miyazaki A.; Nakato A.; Nishimura M.; Soejima H.; Suzuki A.; Yada T.; Yamamoto D.; Yogata K.; Yoshitake M.; Tachibana S. and Yurimoto H., 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., American Association for the Advancement of Science (AAAS)
Science, 2022年06月, ［査読有り］

Hydrothermal activities on C-complex asteroids induced by radioactivity.
Fujiya W.; Higashi H.; Hibiya Y.; Sugawara S.; Yamaguchi A.; Kimura M. and Hashizume K., 筆頭著者,
C-complex asteroids, rich in carbonaceous materials, are potential sources of Earth’s volatile inventories. They are spectrally dark resembling primitive carbonaceous meteorites, and thus, C-complex asteroids are thought to be potential parent bodies of carbonaceous meteorites. However, the substantial number of C-complex asteroids exhibits surface spectra with weaker hydroxyl absorption than water-rich carbonaceous meteorites. Rather, they best correspond to meteorites showing evidence for dehydration, commonly attributed to impact heating. Here, we report an old radiometric age of 4564.7 million years ago for Ca carbonates from the Jbilet Winselwan meteorite analogous to dehydrated C-complex asteroids. The carbonates are enclosed by a high-temperature polymorph of Ca sulfates, suggesting thermal metamorphism at >300°C subsequently after aqueous alteration. This old age indicates the early onset of aqueous alteration and subsequent thermal metamorphism driven by the decay of short-lived radionuclides rather than impact heating. The breakup of original asteroids internally heated by radioactivity should result in asteroid families predominantly consisting of thermally metamorphosed materials. This explains the common occurrence of dehydrated C-complex asteroids., American Astronomical Society
The Astrophysical Journal Letters, 2022年01月, ［査読有り］

Analytical protocols for Phobos regolith samples returned by the Martian Moons eXploration (MMX) mission.
Fujiya W.; Furukawa Y.; Sugahara H.; Koike M.; Bajo K.; Chabot N. L.; Miura Y. N.; Moynier F.; Russell S. S.; Tachibana S.; Takano Y.; Usui T. and Zolensky M. E., 筆頭著者, Japan Aerospace Exploration Agency (JAXA) will launch a spacecraft in 2024 for a sample return mission from Phobos (Martian Moons eXploration: MMX). Touchdown operations are planned to be performed twice at different landing sites on the Phobos surface to collect > 10 g of the Phobos surface materials with coring and pneumatic sampling systems on board. The Sample Analysis Working Team (SAWT) of MMX is now designing analytical protocols of the returned Phobos samples to shed light on the origin of the Martian moons as well as the evolution of the Mars-moon system. Observations of petrology and mineralogy, and measurements of bulk chemical compositions and stable isotopic ratios of, e.g., O, Cr, Ti, and Zn can provide crucial information about the origin of Phobos. If Phobos is a captured asteroid composed of primitive chondritic materials, as inferred from its reflectance spectra, geochemical data including the nature of organic matter as well as bulk H and N isotopic compositions characterize the volatile materials in the samples and constrain the type of the captured asteroid. Cosmogenic and solar wind components, most pronounced in noble gas isotopic compositions, can reveal surface processes on Phobos. Long- and short-lived radionuclide chronometry such as Mn-53-Cr-53 and Rb-87-Sr-87 systematics can date pivotal events like impacts, thermal metamorphism, and aqueous alteration on Phobos. It should be noted that the Phobos regolith is expected to contain a small amount of materials delivered from Mars, which may be physically and chemically different from any Martian meteorites in our collection and thus are particularly precious. The analysis plan will be designed to detect such Martian materials, if any, from the returned samples dominated by the endogenous Phobos materials in curation procedures at JAXA before they are processed for further analyses., SPRINGER
Earth, Planets and Space, 2021年06月, ［査読有り］

Irradiation origin of ¹⁰Be in the solar nebula: Evidence from Li-Be-B and Al-Mg isotope systematics, and REE abundances of CAIs from Yamato-81020 CO3.05 chondrite.
Fukuda K; Hiyagon H; Fujiya W; Kagoshima T; Itano K; Iizuka T; Kita N. T; Sano Y, Elsevier BV
Geochimica et Cosmochimica Acta, 2021年01月, ［査読有り］

The Importance of Phobos Sample Return for Understanding the Mars-Moon System.
Usui, T.; Bajo, K.; Fujiya, W.; Furukawa, Y.; Koike, M.; Miura, Y. N.; Sugahara, H.; Tachibana, S.; Takano, Y.; Kuramoto, K.
Space Science Review, 2020年06月, ［査読有り］

Carbon isotopic evolution of aqueous fluids in CM chondrites: Clues from in-situ isotope analyses within calcite grains in Yamato-791198.
Fujiya W.; Aoki Y.; Ushikubo T.; Hashizume K. and Yamaguchi A., 筆頭著者
Geochimica et Cosmochimica Acta, 2020年04月, ［査読有り］

Origin of the short-lived radionuclide ¹⁰Be and its implications for the astronomical setting of CAI formation in the solar protoplanetary disk.
Fukuda K; Hiyagon H; Fujiya W; Takahata N; Kagoshima T; Sano Y, We report Li?Be?B and Al?Mg isotopic compositions of Ca-Al-rich inclusions (CAIs) in Sayh al Uhaymir 290 (CH) and Isheyevo (CH/CB) metal-rich carbonaceous chondrites. All CAIs studied here do not show resolvable excesses in Mg-26, a decay product of the short-lived radionuclide Al-26, which suggests their formation occurred prior to the injection of Al-26 into the solar system from a nearby stellar source. The inferred initial Be-10/Be-9 ratios obtained for these CAIs range from 0.17;;10(?3) to 6.1;;10(?3), which tend to be much higher and more variable than those of CAIs in CV3 chondrites. The high Be-10/Be-9 ratios suggest that Be-10 was most likely synthesized through solar cosmic-ray irradiation. The lithium isotopic compositions of these CAIs are nearly chondritic, independent of their initial Be-10/Be-9 ratios. This can be explained by the irradiation targets being of chondritic composition; in other words, targets were most likely not solid CAI themselves, but their precursors in solar composition. The larger variations in Be-10/Be-9 ratios observed in CH and CH/CB CAIs than in CV CAIs may reflect more variable cosmic-ray fluxes from the earlier, more active Sun at an earlier evolutionary stage (class 0-I) for the former, and a later, less active stage of the Sun (class II) for the latter. If this is the case, our new Be?B and Al?Mg data set implies that the earliest formed CAIs tend to be transported into the outer part of the solar protoplanetary disk, where the parent bodies of metal-rich chondrites likely accreted., IOP PUBLISHING LTD
The Astrophysical Journal, 2019年11月, ［査読有り］

Migration of D-type asteroids from the outer Solar System inferred from carbonate in meteorites.
Fujiya W; Hoppe P; Ushikubo T; Fukuda K; Lindgren P; Lee M. R; Koike M; Shirai K; Sano Y, 筆頭著者, Recent dynamical models of Solar System evolution and isotope studies of rock-forming elements in meteorites have suggested that volatile-rich asteroids formed in the outer Solar System beyond Jupiter’s orbit, despite being currently located in the main asteroid belt1–4. The ambient temperature under which asteroids formed is a crucial diagnostic to pinpoint the original location of asteroids and is potentially determined by the abundance of volatiles they contain. In particular, abundances and 13C/12C ratios of carbonates in meteorites record the abundances of carbon-bearing volatile species in their parent asteroids. However, the sources of carbon for these carbonates remain poorly understood5–8. Here we show that the Tagish Lake meteorite contains abundant carbonates with consistently high 13C/12C ratios. The high abundance of 13C-rich carbonates in Tagish Lake excludes organic matter as their main carbon source5,9. Therefore, the Tagish Lake parent body, presumably a D-type asteroid10, must have accreted a large amount of 13C-rich CO2 ice. The estimated 13C/12C and CO2/H2O ratios of ice in Tagish Lake are similar to those of cometary ice11,12. Thus, we infer that at least some D-type asteroids formed in the cold outer Solar System and were subsequently transported into the inner Solar System owing to an orbital instability of the giant planets1,3.
Nature Astronomy, 2019年10月, ［査読有り］

Oxygen isotopic ratios of primordial water in carbonaceous chondrites
Wataru Fujiya, In this work, I estimate the δ18O and δ17O values of primordial water in CM chondrites to be 55 ± 13 and 35 ± 9‰ respectively, based on whole-rock O and H data. Also, I found that the O and/or H data of Antarctic meteorites are biased, which is attributed to terrestrial weathering. This characteristic O isotopic ratio of water together with corresponding water abundances in CM chondrites are consistent with the origin of water as ice processed by photochemical reactions at the outer regions of the solar nebula, where mass-independent O isotopic fractionation and water destruction may have occurred. Another possible mechanism to produce the inferred O isotopic ratio of water would be O isotopic fractionation between water vapor and ice, which likely occurred near the condensation front of H2O (snow line) in the solar nebula. The inferred O isotopic ratio of water suggests that carbonate in CM chondrites formed at low temperatures of <
150 °C. The O isotopic ratios of primordial water in chondrites other than CM chondrites are not well constrained., Elsevier B.V.
Earth and Planetary Science Letters, 2018年01月01日, ［査読有り］

Beryllium-boron relative sensitivity factors for melilitic glasses measured with a NanoSIMS ion microprobe
Kohei Fukuda; Wataru Fujiya; Hajime Hiyagon; Yoshiki Makino; Naoji Sugiura; Naoto Takahata; Takafumi Hirata; Yuji Sano, The short-lived radionuclide 10Be (t1/2 = 1.4 Myr) present in the Early Solar System (ESS) provides important information about the astrophysical environment in which the solar system formed. However, the origin of 10Be in the ESS remains controversial. To reveal its origin, it is important to determine precise and accurate 10Be abundances in meteoritic components. The initial 10Be/9Be ratio can be estimated using ion microprobe analysis and a 10B/11B-9Be/11B correlation. The relative sensitivities for Be and B must be determined to obtain 9Be/11B ratios of unknowns. Here, we report Be/B relative sensitivities for synthetic melilitic glasses and silica-rich NIST SRM 610 glass measured with a Nano SIMS ion microprobe. The Be/B relative sensitivities for melilitic glasses are identical to that of the NIST 610 glass within uncertainties, which suggests that the matrix effects, at least between the NIST 610 glass and melilite, are not significant with respect to Be-B measurements. The present results confirm that the observed variations in the 10Be/9Be ratios for CV calcium-aluminum-rich inclusions (CAIs) are real and the origin of 10Be must be attributed to irradiation by the active early sun. It is also inferred that the 10Be/9Be ratios of fractionation and unidentified nuclear effect (FUN) CV CAIs are not significantly lower than those for normal (non-FUN) CV CAIs, suggesting similar formation conditions., The Physiological Society of Japan
Geochemical Journal, 2018年, ［査読有り］

隕石に見られる水質変成作用の年代学と母天体内での物質進化
藤谷渉
地球化学, 2017年03月, ［査読有り］

Boron abundances and isotopic ratios of olivine grains on Itokawa returned by the Hayabusa spacecraft
Wataru Fujiya; Peter Hoppe; Ulrich Ott, We report the B abundances and isotopic ratios of two olivine grains from the S-type asteroid Itokawa sampled by the Hayabusa spacecraft. Olivine grains from the Dar al Gani (DaG) 989 LL6 chondrite were used as a reference. Since we analyzed polished thin sections in both cases, we expect the contribution from the solar wind B (rich in B-10) to be minimal because the solar wind was implanted only within very thin layers of the grain surface. The Itokawa and DaG 989 olivine grains have homogeneous B abundances (similar to 400ppb) and B-11/B-10 ratios compatible with the terrestrial standard and bulk chondrites. The observed homogeneous B abundances and isotopic ratios of the Itokawa olivine grains are likely the result of thermal metamorphism which occurred in the parent asteroid of Itokawa, which had a similar composition as LL chondrites. The chondritic B isotopic ratios of the Itokawa samples suggest that they contain little cosmogenic B (from cosmic-ray spallation reactions) rich in B-10. This observation is consistent with the short cosmic-ray exposure ages of Itokawa samples inferred from the small concentrations of cosmogenic Ne-21. If other Itokawa samples have little cosmogenic B as well, the enrichment in B-10 found previously on the surface of another Itokawa particle (as opposed to the bulk grain study here) may be attributed to implanted solar wind B., WILEY-BLACKWELL
METEORITICS & PLANETARY SCIENCE, 2016年09月, ［査読有り］

エポックメイキングな隕石たち(その８): タギシュ・レイク隕石～D型小惑星由来の隕石～
藤谷渉
日本惑星科学会誌「遊・星・人」, 2016年09月, ［査読有り］

Sources of water and aqueous activity on the chondrite parent asteroids.
Krot A. N; Alexander C. M. O’D; Nagashima K; Ciesla F. J; Fujiya W; Bonal L
In Asteroids IV (P. Michel et al., eds.), 2015年12月, ［査読有り］

Comprehensive study of carbon and oxygen isotopic compositions, trace element abundances, and cathodoluminescence intensities of calcite in the Murchison CM chondrite
Wataru Fujiya; Naoji Sugiura; Yves Marrocchi; Naoto Takahata; Peter Hoppe; Kotaro Shirai; Yuji Sano; Hajime Hiyagon, We have performed in situ analyses of C and O isotopic compositions, trace element concentrations, and cathodoluminescence (CL) intensities on calcite in Murchison, a weakly altered CM chondrite. We found that the trace element (Mg, Mn, and Fe) concentrations are heterogeneous within single calcite grains. Grain to grain heterogeneity is even more pronounced. The analyzed calcite grains can be separated into two distinct types with respect to their C isotopic ratios, trace element concentrations, and CL characteristics: Calcite grains with higher delta C-13(PDB) values (similar to 7 parts per thousand) have low trace element concentrations and uniformly dark CL, while grains with lower delta C-13(PDB) values (similar to 35 parts per thousand) have higher trace element concentrations and CL zoning. In contrast to the C isotopic ratios, O isotopic ratios are similar for both types of calcites (delta(18)(OSMOW) similar to 34 parts per thousand).
The O isotopic ratios, trace element concentrations, and CL characteristics provide no evidence for C-isotope evolution in fluids from a single C reservoir by Rayleigh-type isotope fractionation (i.e., removal of C-bearing gaseous species). Also, it seems difficult to explain the O and C isotopic compositions of the two types of calcites by their formation at different temperatures from a single fluid. Instead, the delta C-13(PDB) variation suggests the presence of at least two C reservoirs with different isotopic ratios in the aqueous fluids from which the calcites precipitated. The C reservoirs with lower delta C-13 values are likely to be organic matter. The same holds for the C reservoirs with higher d delta C-13 values which might have significant contributions from the C-13-enriched grains identified in meteoritic insoluble organic matter. Thermodynamic calculations show that calcite with lower Fe concentrations formed under more reduced conditions than calcite with higher Fe concentrations. If this is the case, the C-13-rich organic grains may have been destroyed and dissolved in the fluids under more reduced conditions than other organic components. The fact that the two types of calcites were found in different domains in the same thin section suggests that microenvironments with diverse physicochemical conditions such as redox states were present at scales of 100' s mu m. (C) 2015 Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
GEOCHIMICA ET COSMOCHIMICA ACTA, 2015年07月, ［査読有り］

Sulfur in presolar silicon carbide grains from asymptotic giant branch stars
Peter Hoppe; Katharina Lodders; Wataru Fujiya, We studied 14 presolar SiC mainstream grains for C-, Si-, and S-isotopic compositions and S elemental abundances. Ten grains have low levels of S contamination and CI chondrite-normalized S/Si ratios between 2x10(-5) and 2x10(-4). All grains have S-isotopic compositions compatible within 2 sigma of solar values. Their mean S isotope composition deviates from solar by at most a few percent, and is consistent with values observed for the carbon star IRC+10216, believed to be a representative source star of the grains, and the interstellar medium. The isotopic data are also consistent with stellar model predictions of low-mass asymptotic giant branch (AGB) stars. In a S-33 versus S-34 plot the data fit along a line with a slope of 1.8 +/- 0.7, suggesting imprints from galactic chemical evolution. The observed S abundances are lower than expected from equilibrium condensation of CaS in solid solution with SiC under pressure and temperature conditions inferred from the abundances of more refractory elements in SiC. Calcium to S abundance ratios are generally above unity, contrary to expectations for stoichiometric CaS solution in the grains, possibly due to condensation of CaC2 into SiC. We observed a correlation between Mg and S abundances suggesting solid solution of MgS in SiC. The low abundances of S in mainstream grains support the view that the significantly higher abundances of excess S-32 found in some Type AB SiC grains are the result of insitu decay of radioactive Si-32 from born-again AGB stars that condensed into AB grains., WILEY-BLACKWELL
METEORITICS & PLANETARY SCIENCE, 2015年06月, ［査読有り］

Correlated accretion ages and epsilon Cr-54 of meteorite parent bodies and the evolution of the solar nebula
Naoji Sugiura; Wataru Fujiya, We look at the relationship between the value of epsilon Cr-54 in bulk meteorites and the time (after calcium-aluminum-rich inclusion, CAI) when their parent bodies accreted. To obtain accretion ages of chondrite parent bodies, we estimated the maximum temperature reached in the insulated interior of each parent body, and estimated the initial Al-26/Al-27 for this temperature to be achieved. This initial Al-26/Al-27 corresponds to the time (after CAI formation) when cold accretion of the parent body would have occurred, assuming Al-26/Al-27 throughout the solar system began with the canonical value of 5.2x10(-5). In cases of iron meteorite parent bodies, achondrite parent bodies, and carbonaceous chondrite parent bodies, we use published isotopic ages of events (such as core formation, magma crystallization, and growth of secondary minerals) in each body's history to obtain the probable time of accretion. We find that epsilon Cr-54 correlates with accretion age: the oldest accretion ages (1 +/- 0.5Ma) are for iron and certain other differentiated meteorites with epsilon Cr-54 of -0.75 +/- 0.5, and the youngest ages (3.5 +/- 0.5Ma) are for hydrated carbonaceous chondrites with epsilon Cr-54 values of 1.5 +/- 0.5. Despite some outliers (notably Northwest Africa [NWA] 011 and Tafassasset), we feel that the correlation is significant and we suggest that it resulted from late, localized injection of dust with extremely high epsilon Cr-54., WILEY-BLACKWELL
METEORITICS & PLANETARY SCIENCE, 2014年05月, ［査読有り］

Ion microprobe Al-Mg dating for a single plagioclase grain in an Efremovka chondrule.
Sano Y.; Takada M.; Takahata N.; Fujiya W. and Sugiura N., We report here technical details of Al-26-Mg-26 dating of single plagioclase grains located in a chondrule of the Efremovka CV3 chondrite using a high spatial resolution secondary ion mass spectrometer (NanoSIMS). A ca. 500 pA mass filtered O-16(-) primary beam was used to sputter 5-7 mu m diameter craters. Secondary positive beams were extracted for mass analysis. We detected Al-27(++) (at mass 13.5), Mg-24(+), Mg-25(+), and Mg-26(+) simultaneously under a static magnetic field for the first session. To obtain accurate Mg isotopic ratios but at the expense of a longer analytical time, we have also measured,, (Mg-24 Mg-25 Mg-26) using a single detector with a magnet scanning mode. Apparent Mg-26 excesses were observed in small plagioclase grains (#1 and #4) of the chondrule. A positive correlation between the Al/Mg ratio and the excesses 26Mg engender a Al-26-Mg-26 isochron with an initial Al-26/Al-27 ratio of (3.3 +/- 1.3) x 10(-6) for #1 and (1.7 +/- 1.4) x 10-6 for #4. In contrast, large plagioclase grains (#2 and #3) show no resolvable excesses Mg-26. The initial Al-26/Al-27 ratios of -(0.13 +/- 0.71) x 10-6 (#2) and -(0.12 +/- 1.26) x 10(-6) (#3) are consistent with zero. A substantial difference exists among the initial Al-26/Al-27 ratios of individual grains in the same Efremovka chondrule, which may be attributable to parent body alteration of the meteorite. Careful treatment is necessary to calculate the formation age combining the data from different grains, even in a single chondrule., GEOCHEMICAL SOC JAPAN
Geochemical Journal, 2014年03月, ［査読有り］

EVIDENCE FOR RADIOGENIC SULFUR-32 IN TYPE AB PRESOLAR SILICON CARBIDE GRAINS?
Wataru Fujiya; Peter Hoppe; Ernst Zinner; Marco Pignatari; Falk Herwig, We report C, Si, and S isotope measurements on 34 presolar silicon carbide grains of Type AB, characterized by C-12/C-13 < 10. Nitrogen, Mg-Al-, and Ca-Ti-isotopic compositions were measured on a subset of these grains. Three grains show large S-32 excesses, a signature that has been previously observed for grains from supernovae (SNe). Enrichments in S-32 may be due to contributions from the Si/S zone and the result of S molecule chemistry in still unmixed SN ejecta or due to incorporation of radioactive Si-32 from C-rich explosive He shell ejecta. However, a SN origin remains unlikely for the three AB grains considered here, because of missing evidence for Ti-44, relatively low Al-26/Al-27 ratios (a few times 10(-3)), and radiogenic S-32 along with low C-12/C-13 ratios. Instead, we show that born-again asymptotic giant branch (AGB) stars that have undergone a very-late thermal pulse (VLTP), known to have low C-12/C-13 ratios and enhanced abundances of the light s-process elements, can produce Si-32, which makes such stars attractive sources for AB grains with S-32 excesses. This lends support to the proposal that at least some AB grains originate from born-again AGB stars, although uncertainties in the born-again AGB star models and possible variations of initial S-isotopic compositions in the parent stars of AB grains make it difficult to draw a definitive conclusion., IOP PUBLISHING LTD
ASTROPHYSICAL JOURNAL LETTERS, 2013年10月, ［査読有り］

Mn-Cr ages of carbonates in CI chondrites and the Tagish Lake ungrouped carbonaceous chondrite.
Fujiya W.; Sugiura N.; Sano Y. and Hiyagon H., 筆頭著者, Mn-53-Cr-53 ages have been measured for dolomites in three CI chondrites and an ungrouped C2 chondrite Tagish Lake. For an accurate age determination, we utilized, in contrast to previous works, a matrix-matched carbonate standard to appropriately correct the observed Mn/Cr ratios. The Mn-Cr data of the dolomites most likely represent isochrons with chronological significances and the obtained ages are concentrated in 4563.8-4562.5 million years ago (4.4-5.7 million years after the birth of the solar system). The ages of the Cl and Tagish Lake dolomites are very similar to those of carbonates in CM chondrites, although CI and CM chondrites are likely to have different alteration histories. The similar carbonate ages in various carbonaceous chondrites suggest that the aqueous activities in hydrous asteroids initiated almost concurrently. If this is the case, the most plausible heat source for the aqueous alteration is the decay energy of short-lived radionuclides, especially Al-26. We carried out a model calculation for the thermal history of the CI chondrite parent body assuming that Al-26 is the dominant heat source. By two different approaches to estimate the accretion time of the CI chondrite parent body, we conclude that it accreted 3.0-3.9 million years after the birth of the solar system. This is also likely to be the case for the CM chondrite and Tagish Lake parent bodies, because the result of the calculation is not sensitive to the ice abundance. Therefore, we stress that near the condensation front of water ice, meteorite parent bodies with abundant ice accreted almost simultaneously at 3-4 million years after CAI formation. Combining our Mn-Cr ages of the dolomites with those of breunnerites reported previously (the youngest one is 4554.6 million years ago), we found that the aqueous alteration in the Cl chondrite parent body lasted for at least 9 million years. Therefore, the parent body should be large enough ( > 50 km in radius) so that the internal heat had been kept for 9 million years. (C) 2012 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Earth and Planetary Science Letters, 2013年01月, ［査読有り］

隕石中の炭酸塩の年代測定から探る含水小惑星の形成と進化
藤谷渉, 太陽系の最初期に誕生した微惑星のうち,特に水や揮発性元素,有機物に富むもの(現在のC,D型小惑星)の形成過程を解明するため,隕石中の炭酸塩に対して,高精度かつ高確度のマンガン・クロム年代測定を行った.分析した4種類のCMコンドライトおよび4種類のCIコンドライト中の炭酸塩は太陽系形成から430-570万年後というほぼ同一の形成年代を示した.炭酸塩は水の存在する環境で形成し,酸素同位体などから形成したときの温度がわかっている.短寿命放射性核種の壊変熱を熱源と仮定して微惑星形成以後の熱史を数値計算し,炭酸塩の形成年代にその温度の水が存在するように微惑星の形成年代に制約を与えたところ,CM, CIコンドライトの母天体は太陽系形成から約350万年後に形成したことが明らかになった., 日本惑星科学会
日本惑星科学会誌「遊・星・人」, 2012年12月, ［査読有り］

Exploring the neutrino mass hierarchy probability with meteoritic supernova material, v-process nucleosynthesis, and theta(13) mixing
G. J. Mathews; T. Kajino; W. Aoki; W. Fujiya; J. B. Pitts, There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced v-process B-11 and or Li-7 encapsulated in the grains. The synthesis of B-11 and Li-7 via neutrino-induced nucleon emission (the v process) in supernovas is sensitive to the neutrino mass hierarchy for finite sin(2)2 theta(13) > 0.001. This sensitivity arises because, when there is 13 mixing, the average electron neutrino energy for charged-current neutrino reactions is larger for a normal mass hierarchy than for an inverted hierarchy. Recent constraints on theta(13) from the Daya Bay, Double Chooz, MINOS, RENO, and T2K collaborations all suggest that indeed sin(2)2 theta(13) > 0.001. We examine the possible implications of these new results based upon a Bayesian analysis of the uncertainties in the measured meteoritic material and the associated supernova nucleosynthesis models. We show that although the uncertainties are large, they hint at a marginal preference for an inverted neutrino mass hierarchy. We discuss the possibility that an analysis of more X grains enriched in Li and B along with a better understanding of the relevant stellar nuclear and neutrino reactions could eventually reveal the neutrino mass hierarchy., AMER PHYSICAL SOC
PHYSICAL REVIEW D, 2012年05月, ［査読有り］

SULFUR MOLECULE CHEMISTRY IN SUPERNOVA EJECTA RECORDED BY SILICON CARBIDE STARDUST
Peter Hoppe; Wataru Fujiya; Ernst Zinner, We studied about 3400 presolar silicon carbide (SiC) grains from the Murchison CM2 meteorite for C- and Si-isotopic compositions. Among these grains we identified 7 unusual or type C SiC (U/C) grains, characterized by isotopically heavy Si, and 36 supernova type X SiC grains, characterized by isotopically light Si. Selected U/C and X grains were also measured for S-, Mg-Al-, and Ca-Ti-isotopic compositions. We show that the U/C grains incorporated radioactive Ti-44, which is evidence that they formed in the ejecta of Type II supernova (SNII) explosions. Abundances of radioactive Al-26 and Ti-44 are compatible with those observed in X grains. U/C and X grains carry light S with enrichments in S-32 of up to a factor of 2.7. The combination of heavy Si and light S observed in U/C grains is not consistent with abundance predictions of simple supernova models. The isotope data suggest preferential trapping of S from the innermost supernova zones, the production site of radioactive Ti-44, by the growing silicon carbide particles. A way to achieve this is by sulfur molecule chemistry in the still unmixed ejecta. This confirms model predictions of molecule formation in SNII ejecta and shows that sulfur molecule chemistry operates in the harsh and hot environments of stellar explosions., IOP PUBLISHING LTD
ASTROPHYSICAL JOURNAL LETTERS, 2012年02月, ［査読有り］

Evidence for the late formation of hydrous asteroids from young meteoritic carbonates
Wataru Fujiya; Naoji Sugiura; Hideyuki Hotta; Koji Ichimura; Yuji Sano, The accretion of small bodies in the Solar System is a fundamental process that was followed by planet formation. Chronological information of meteorites can constrain when asteroids formed. Secondary carbonates show extremely old Mn-53-Cr-53 radiometric ages, indicating that some hydrous asteroids accreted rapidly. However, previous studies have failed to define accurate Mn/Cr ratios; hence, these old ages could be artefacts. Here we develop a new method for accurate Mn/Cr determination, and report a reliable age of 4,563.4+0.4/-0.5 million years ago for carbonates in carbonaceous chondrites. We find that these carbonates have identical ages, which are younger than those previously estimated. This result suggests the late onset of aqueous activities in the Solar System. The young carbonate age cannot be explained if the parent asteroid accreted within 3 million years after the birth of the Solar System. Thus, we conclude that hydrous asteroids accreted later than differentiated and metamorphosed asteroids., NATURE PUBLISHING GROUP
NATURE COMMUNICATIONS, 2012年01月, ［査読有り］

In-situ chromium isotope measurement of chromium-rich fine grains in the Murchison CM2 chondrite.
Fujiya W.; Sugiura N.; Takahata N. and Hiyagon H., 筆頭著者, Isotopic anomalies of Cr-54 have been reported in bulk chondrites. Stepwise dissolution experiments have suggested the presence of a carrier of the Cr-54 anomaly, probably of presolar origin. Although stepwise dissolution experiments and ion microprobe studies of Cr-rich grains have revealed, to some extent, the carrier of anomalous Cr-54, the nature of the carrier is not yet well understood. In this study, we attempted to detect the carrier phases. We performed an in-situ measurement of Cr isotopic compositions of small (similar to 1 mu m or less in size) Cr-bearing grains in the Murchison CM2 chondrite using a NanoSIMS 50 ion microprobe. Cr-54 has an isobaric interference of Fe-54, which makes the measurement of Cr-54/Cr-52 isotopic ratios difficult. In order to evaluate the contribution of Fe-54, the abundance of Fe-56 was measured. Even after large corrections for Fe-54, (delta Cr-54 values of Cr-rich grains were determined with a precision of similar to 30 parts per thousand.
No grain out of similar to 200 Cr-rich grains was confirmed to be a presolar grain with a large Cr-54 anomaly. If the carrier of the Cr-54 anomaly is Cr-rich, this result implies a low abundance and a huge isotopic anomaly of the carrier, and/or its extremely fine grain size. In the former case, the maximum abundance of the presolar Cr-rich grains is roughly estimated to be similar to 1 ppm. In that case the minimum isotopic anomaly would be similar to 90 parts per thousand., GEOCHEMICAL SOC JAPAN
Geochemical Journal, 2011年08月, ［査読有り］

HINTS FOR NEUTRINO-PROCESS BORON IN PRESOLAR SILICON CARBIDE GRAINS FROM SUPERNOVAE
Wataru Fujiya; Peter Hoppe; Ulrich Ott, We have studied more than 1000 presolar silicon carbide (SiC) grains from the Murchison CM2 chondrite for C- and Si-isotopic compositions. Twelve SiC X grains, characterized by strong enrichments in Si-28 and believed to originate from Type II Supernovae (SNeII), were also measured for Li- and B-isotopic compositions. None of these grains show resolvable isotope anomalies in Li or B. For the seven X grains without Li and B contributions from nearby or attached SiC grains of distinct origins we find on average Li-7/Li-6 = 11.83 +/- 0.29 (solar system: 12.06) and B-11/B-10 = 4.68 +/- 0.31 (solar system: 4.03). The average Li-7/Li-6 is compatible with the solar system ratio and the lithium in the X grains is likely largely dominated by contaminating Li of laboratory or meteoritic origin. Also, most of the boron in X grains appears to be contamination but the small B-11 excess of similar to 16%, significant at the 2 sigma level, can be considered a hint for the presence of boron produced by the neutrino process in the parent SNeII. Despite this finding, a quantitative comparison of the B isotope and abundance data of X grains with model predictions reveals deficiencies in our current understanding of the details of B production in SNeII as well as on B chemistry and condensation in SNII ejecta., IOP PUBLISHING LTD
ASTROPHYSICAL JOURNAL LETTERS, 2011年03月, ［査読有り］

Mn/Cr relative sensitivity for calcium carbonate measured with a NanoSIMS.
Sugiura N.; Ichimura K.; Fujiya W. and Takahata N., Mn/Cr relative sensitivities for a synthetic calcite and a terrestrial olivine (San Carlos olivine) were measured using spot and rasterized modes with a NanoSIMS ion probe Counting rates of Ca-43(+), Cr-52(+) Cr-53(+) and Mn-55(+) from the synthetic calcite by spot analysis mode decreased with time (and depth of crater) This may be Interpreted as due to charge-up of the deep crater formed by primary ion bombardment because of poor conductivity of carbonate The relative Mn/Cr sensitivity of carbonate measured by spot analysis mode decreased with time It may be necessary to use a time dependent relative sensitivity factor for chronological studies of meteoritic carbonates The time-averaged RSF for the calcite spot analysis is significantly lower than that for San Carlos olivine The instrumental isotopic fractionation of the Cr-53/Cr-52 ratio measured with the NanoSIMS 50 seems to be different between the calcite and San Carlos olivine, GEOCHEMICAL SOC JAPAN
Geochemical Journal, 2010年12月, ［査読有り］

隕石中の炭酸塩のMn-Cr年代測定　　　　　　　　　　　　　　　
藤谷渉,杉浦直治,市村康治,高畑直人,佐野有司, 筆頭著者
日本惑星科学会誌「遊・星・人」, 2010年06月, ［査読有り］

火星衛星探査計画MMX・SAWTによる帰還試料の初期記載・初期分析の検討
深井 稜汰; 臼井 寛裕; 藤谷 渉; 高野 淑識; 馬上 謙一; 小池 みずほ; 三浦 弥生; Andrew Beck; Enrica Bonato; Nancy L. Chabot; Frederic Moynier; Sara S. Russell; 玄田 英典; 古川 善博; 松岡 萌; 菅原 春菜; 橘 省吾; Michael E. Zolensky; 坂本 佳奈子; 安部 正真
日本地球化学会年会要旨集, 2022年

LI-BE-B AND AL-MG ISOTOPIC COMPOSITIONS IN CH AND CH/CB CAIS: IMPLICATION FOR THE ORIGIN OF (BE)-B-10 IN THE EARLY SOLAR SYSTEM
K. Fukuda; W. Fujiya; H. Hiyagon; N. Takahata; T. Kagoshima; N. Sugiura; Y. Sano
METEORITICS & PLANETARY SCIENCE, 2017年08月

AN ION MICROPROBE STUDY OF BE-B ISOTOPE SYSTEMATICS IN MELILITE-RICH CAIS BASED ON NEWLY DETERMINED Be/B RELATIVE SENSITIVITY FACTORS FOR MELILITIC GLASS STANDARDS.
K. Fukuda; W. Fujiya; H. Hiyagon; N. Sugiura; N. Takahata; Y. Sano
METEORITICS & PLANETARY SCIENCE, 2016年08月

Carbon and O isotopic ratios, trace element abundances and cathodoluminescence observation of calcite in Murchison.
W. Fujiya; N. Sugiura; Y. Marrocchi; N. Takahata; P. Hoppe; K. Shirai; Y. Sano; H. Hiyagon
METEORITICS & PLANETARY SCIENCE, 2014年09月

S11-06P マーチソン(CM2)隕石から抽出したヒボナイト包有物のNanoSIMSによるAl-Mg同位体分析(一般ポスターセッション1,ポスター発表)
佐々木 翔吾; 比屋根 肇; 藤谷 渉; 高畑 直人; 佐野 有司
日本惑星科学会秋期講演会予稿集, 2011年10月23日

SP1-03 隕石中の炭酸塩の年代測定から探る含水小惑星の形成と進化(特別セッション1<最優秀発表賞>,口頭発表)
藤谷 渉; 杉浦 直治; 佐野 有司; 比屋根 肇
日本惑星科学会秋期講演会予稿集, 2011年10月23日

ALTERATION HISTORY IN THE CI CHONDRITE PARENT BODY INFERRED FROM Mn-Cr DATING OF CAROBNATES
W. Fujiya; N. Sugiura; Y. Sano
METEORITICS & PLANETARY SCIENCE, 2011年07月

AL-MG DATING OF A CHONDRULE IN EFREMOVKA USING NANOSIMS
Y. Sano; N. Takahata; N. Sugiura; W. Fujiya
METEORITICS & PLANETARY SCIENCE, 2009年07月

A PRELIMINARY STUDY ON (MN)-M-55/(CR)-C-52 RELATIVE SENSITIVITY FOR A SYNTHETIC CALCITE: IMPLICATIONS
N. Sugiura; K. Ichimura; W. Fujiya; N. Takahata; Y. Sano
METEORITICS & PLANETARY SCIENCE, 2009年07月

生命起源の事典 = Origin of life
薮田, ひかる; 川村, 邦男; 赤沼, 哲史; 木賀, 大介; 根本, 直人; 古川, 善博; 横堀, 伸一; 生命の起原および進化学会, 分担執筆
朝倉書店, 2024年04月
9784254160789

53Mn-53Cr ages of dolomite in Ryugu samples and the thermal history of the Ryugu parent body　　　　　　　　　　　　　　　
Fujiya W.; Ushikubo T.; Sugawara S.; Yamaguchi A.; Fukuda K.; Lee M. R.; Terada K.; Bland P. A.; Travis B. J.
Hayabusa 2024 Symposium, 2024年11月

Oxygen isotopic compositions of dolomite in Ryugu samples: Constraints on the thermal history of the Ryugu parent body.　　　　　　　　　　　　　　　
Fujiya W.; Ushikubo T.; Sugawara S.; Yamaguchi A.; Fukuda K.; Lee M. R.; Terada K.; Bland P. A.; Travis B. J.
87th Annual Meteoritical Society Meeting, 2024年07月

Oxygen isotopic composition of dolomite in Ryugu: New insights into the thermal history of the Ryugu parent body　　　　　　　　　　　　　　　
Fujiya W.; Ushikubo T.; Sugawara S.; Yamaguchi A.; Fukuda K.; Lee M. R.; Terada K.; Bland P. A. and Travis B. J
Hayabusa 2023 Symposium, 2023年11月

On the Mn-Cr dating of Ryugu carbonates using ion-implanted standard materials　　　　　　　　　　　　　　　
Fujiya W.; Kogiso R.; Sugawara S. and Hashizume K.
86th Annual Meteoritical Society Meeting, 2023年08月

Chronology of metasomatic/aqueous alteration　　　　　　　　　　　　　　　
Fujiya W.; Krot A. N. and Pravdivtseva O. V.
ISSI Workshop on “Evolution of the Solar System: Constraints from Meteorites”, 2023年06月

Scientific importance of the sample analyses of Phobos regolith and the analytical protocols of returned samples by the MMX mission　　　　　　　　　　　　　　　
Fujiya W.; Furukawa Y.; Sugahara H.; Koike M.; Bajo K.; Chabot N. L.; Miura Y. N.; Moynier F.; Russell S. S.; Tachibana S.; Takano Y.; Usui T. and Zolensky M. E.
Hayabusa 2021 Symposium, 2021年11月, ［招待有り］

Small body exploration for understanding of Earth’s building blocks　　　　　　　　　　　　　　　
Fujiya W.
ISAS Planetary Exploration Workshop 2021, 2021年09月, ［招待有り］

小惑星と火星圏の物質輸送（MMX）　　　　　　　　　　　　　　　
藤谷渉
第22回 惑星圏研究会, 2021年02月, ［招待有り］

Material transport in the Solar System: Insights from MMX sample analysis　　　　　　　　　　　　　　　
Fujiya W.
4th MMX Science Team Meeting, 2021年02月, ［招待有り］

Evolution of thermally metamorphosed C-complex asteroids inferred from a heated CM chondrite Jbilet Winselwan　　　　　　　　　　　　　　　
Fujiya W; Higashi H; Hibiya Y; Sugawara S; Yamaguchi A; Kimura M; Hashizume K
JpGU-AGU Joint Meeting 2020: Virtual, 2020年07月, ［招待有り］

「惑星材料・揮発性物質の分布・供給」のマイルストーン　　　　　　　　　　　　　　　
藤谷渉
惑星科学探査の将来構想検討会：RFI回答文書改訂2019, 2019年10月, ［招待有り］

小惑星の揮発性物質存在量　　　　　　　　　　　　　　　
藤谷渉
2019年度日本地球化学会年会, 2019年09月, ［招待有り］

Primitive meteorites with abundant water.　　　　　　　　　　　　　　　
Fujiya W
JSPS Core-to-Core Program “Planet2” Symposium 2017, 2017年02月, ［招待有り］

水質変成の年代学と物質進化　　　　　　　　　　　　　　　
藤谷渉
衝突研究会2016, 2016年11月, ［招待有り］

プレソーラー炭化ケイ素粒子の硫黄同意体組成、元素存在度　　　　　　　　　　　　　　　
藤谷渉
「プレソーラー粒子から探る星間ダストの進化と太陽系の起源」研究会, 2016年09月, ［招待有り］

Current status and future prospect of isotope cosmochemistry and mass spectrometry.　　　　　　　　　　　　　　　
Fujiya W
Pre-Forum Meeting on Future Cosmochemistry for the JSPS “Science in Japan Forum 2016, 2016年06月, ［招待有り］

含水コンドライト母天体の形成年代・場所　　　　　　　　　　　　　　　
藤谷渉
日本地球惑星科学連合大会2015年大会, 2015年05月, ［招待有り］

Lithium, boron and light noble gas analyses on the surface of the Itokawa asteroidal regolith returned by the Hayabusa mission.　　　　　　　　　　　　　　　
Fujiya W; Hoppe P; Ott U; Meier M. M. M
Hayabusa 2013: Symposium of the Solar System Materials, 2013年10月, ［招待有り］

日本地球惑星科学連合

日本惑星科学会

日本地球化学会

American Geophysical Union

Geochemical Society

The Meteoritical Society

原始惑星系円盤外縁部に存在した太陽系第三世界の初期状態の解明
基盤研究(A)
東北大学
2024年04月 - 2029年03月

宇宙塵と小天体の中間赤外分光の比較と分析から解明する太陽系小天体の大規模軌道変化
基盤研究(A)
京都大学
2024年04月 - 2029年03月

マルチタイムスケール局所年代分析手法の開発： 太陽系年代学の高度化を目指して
基盤研究(A)
大阪大学
2023年04月 - 2028年03月

水熱変成作用を受けた炭素質コンドライト隕石から探るC型小惑星の熱進化
基盤研究(B)
茨城大学
2022年04月 - 2025年03月

深宇宙プローブとしての窒素同位体研究
基盤研究(A)
茨城大学
2020年04月 - 2025年03月

イオン注入を利用した二次イオン質量分析法の高感度化への挑戦
挑戦的研究(萌芽)
茨城大学
2020年07月 - 2024年03月

彗星塵とされてきた宇宙塵は彗星起源なのか？：分析と分光観測からのアプローチ
基盤研究(A)
2019年04月 - 2024年03月

惑星の成り立ちと進化に関する研究　　　　　　　　　　　　　　　
特⾊研究加速イニシアティブ
2021年04月 - 2022年03月

惑星探査計画で回収される地球外物質の分析手法の開発　　　　　　　　　　　　　　　
特⾊研究加速イニシアティブ
2020年04月 - 2021年03月

含水微惑星の衝突年代から読み解く惑星への水の供給ダイナミクス
新学術領域研究(研究領域提案型)
茨城大学
2018年04月 - 2020年03月

微小炭酸塩鉱物の局所高精度同位体比分析による地球惑星表層環境研究への挑戦
挑戦的研究(萌芽)
国立研究開発法人海洋研究開発機構
2017年06月 - 2020年03月

月岩石中カリ長石に含まれる窒素・水素同位体から解読する水惑星・地球の起源と進化
基盤研究(B)
茨城大学
2017年04月 - 2020年03月

隕石中の炭酸塩の微小領域分析から探る始原的有機物の同位体組成とその起源
若手研究(B)
茨城大学
2016年04月 - 2020年03月

高精度Mn－Cr年代測定を用いた微惑星の形成と進化過程の解明
特別研究員奨励費
東京大学
2011年 - 2012年

いん石からひもとく太陽系の歴史、地球のなりたち　　　　　　　　　　　　　　　
出演
特定非営利活動法人ひと・まちねっとわーく, いばらき子ども大学, 2024年12月07日

　　　隕石誕生 木星の外でも　　　　　　　　　　　　　　　
読売新聞社, 読売新聞, 2019年07月28日, 新聞・雑誌

　　　40億年前に土星や天王星が大移動？ 隕石の分析で　　　　　　　　　　　　　　　
日本放送協会, おはよう日本, 2019年07月13日, テレビ・ラジオ番組

　　　小惑星 木星の外側で誕生→移動？　　　　　　　　　　　　　　　
中日新聞東京本社, 東京新聞, 2019年07月03日, 新聞・雑誌

　　　小惑星の大きな移動、隕石分析で解明 茨城大など　　　　　　　　　　　　　　　
日本経済新聞社, 日本経済新聞, 2019年07月02日, 新聞・雑誌

　　　小惑星誕生に新年代測定法 東大理学系研究科博士課程の藤谷さんら提案　　　　　　　　　　　　　　　
朝日新聞社, 朝日新聞, 2012年01月30日, 新聞・雑誌

　　　水を含む小惑星の形成、太陽系誕生の３５０万年後、東大チームが分析・解明　　　　　　　　　　　　　　　
日本経済新聞社, 日本経済新聞, 2012年01月18日, 新聞・雑誌