Geochemical Perspectives Letters
Geochemical
Perspectives Letters
Geochemical
Perspectives
  • Submit here
  • Track your paper
  • For authors
  • e-Alerts
  • Home
  • About
    • About the journal
    • Editorial Board
    • Publication Policy
    • Publication Ethics
  • Submission & Review
    • Copyright & Permissions
    • Information for Authors
    • Information for Reviewers
  • Current issue
  • All issues
  • Submit
Select Page Menu

by admin | Oct 19, 2022 | mainpost, vol24

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

24

2238

28

June

2022

19

September

2022

19

October

2022

1

6

0

Next article >> << Previous article

The Solar System calcium isotopic composition inferred from Ryugu samples

F. Moynier1,

1Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France

W. Dai1,

1Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France

T. Yokoyama2,

2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan

Y. Hu1,

1Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France

M. Paquet1,

1Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France

Y. Abe3,

3Graduate School of Engineering Materials Science and Engineering, Tokyo Denki University, Tokyo 120-8551, Japan

J. Aléon4,

4Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, Museum National d’Histoire Naturelle, CNRS UMR 7590, IRD, 75005 Paris, France

C.M.O’D. Alexander5,

5Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, 20015, USA

S. Amari6,

6McDonnell Center for the Space Sciences and Physics Department, Washington University, St. Louis, MO 63130, USA

Y. Amelin7,

7Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, GD 510640, China

K.-I. Bajo8,

8Natural History Sciences, IIL, Hokkaido University, Sapporo 001-0021, Japan

M. Bizzarro9,1,

9Centre for Star and Planet Formation, GLOBE Institute, University of Copenhagen, Copenhagen, K 1350, Denmark
1Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France

A. Bouvier10,

10Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth 95447, Germany

R.W. Carlson5,

5Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, 20015, USA

M. Chaussidon1,

1Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France

B.-G. Choi11,

11Department of Earth Science Education, Seoul National University, Seoul 08826, Republic of Korea

N. Dauphas12,

12Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago 60637, USA

A.M. Davis12,

12Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago 60637, USA

T. Di Rocco13,

13Faculty of Geosciences and Geography, University of Göttingen, Göttingen, D-37077, Germany

W. Fujiya14,

14Faculty of Science, Ibaraki University, Mito 310-8512, Japan

R. Fukai15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

I. Gautam2,

2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan

M.K. Haba2,

2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan

Y. Hibiya16,

16General Systems Studies, The University of Tokyo, Tokyo 153-0041, Japan

H. Hidaka17,

17Earth and Planetary Sciences, Nagoya University, Nagoya 464-8601, Japan

H. Homma18,

18Osaka Application Laboratory, SBUWDX, Rigaku Corporation, Osaka 569-1146, Japan

P. Hoppe19,

19Max Planck Institute for Chemistry, Mainz 55128, Germany.

G.R. Huss20,

20Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA

K. Ichida21,

21Analytical Technology, Horiba Techno Service Co., Ltd., Kyoto 601-8125, Japan

T. Iizuka22,

22Earth and Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan

T.R. Ireland23,

23School of Earth and Environmental Sciences, The University of Queensland, St Lucia QLD 4072, Australia

A. Ishikawa2,

2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan

M. Ito24,

24Kochi Institute for Core Sample Research, JAMSTEC, Kochi 783-8502, Japan

S. Itoh25,

25Earth and Planetary Sciences, Kyoto University, Kyoto 606-8502, Japan

N. Kawasaki8,

8Natural History Sciences, IIL, Hokkaido University, Sapporo 001-0021, Japan

N.T. Kita26,

26Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA

K. Kitajima26,

26Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA

T. Kleine27,

27Max Planck Institute for Solar System Research; 37077 Göttingen, Germany

S. Komatani21,

21Analytical Technology, Horiba Techno Service Co., Ltd., Kyoto 601-8125, Japan

A.N. Krot20,

20Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA

M.-C. Liu28,

28Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095, USA

Y. Masuda2,

2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan

K.D. McKeegan28,

28Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095, USA

M. Morita21,

21Analytical Technology, Horiba Techno Service Co., Ltd., Kyoto 601-8125, Japan

K. Motomura29,

29Thermal Analysis, Rigaku Corporation, Tokyo 196-8666, Japan

I. Nakai29,

29Thermal Analysis, Rigaku Corporation, Tokyo 196-8666, Japan

K. Nagashima20,

20Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA

D. Nesvorný30,

30Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA

A. Nguyen31,

31Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, TX 77058, USA

L. Nittler5,

5Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, 20015, USA

M. Onose21,

21Analytical Technology, Horiba Techno Service Co., Ltd., Kyoto 601-8125, Japan

A. Pack13,

13Faculty of Geosciences and Geography, University of Göttingen, Göttingen, D-37077, Germany

C. Park32,

32Earth-System Sciences, Korea Polar Research Institute, Incheon 21990, Korea

L. Piani33,

33Centre de Recherches Pétrographiques et Géochimiques, CNRS - Université de Lorraine, 54500 Nancy, France

L. Qin34,

34University of Science and Technology of China, School of Earth and Space Sciences, Anhui 230026, China

S.S. Russell35,

35Department of Earth Sciences, Natural History Museum, London, SW7 5BD, UK

N. Sakamoto36,

36IIL, Hokkaido University, Sapporo 001-0021, Japan

M. Schönbächler37,

37Institute for Geochemistry and Petrology, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland

L. Tafla28,

28Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095, USA

H. Tang28,

28Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095, USA

K. Terada38,

38Earth and Space Science, Osaka University, Osaka 560-0043, Japan

Y. Terada39,

39Spectroscopy and Imaging, Japan Synchrotron Radiation Research Institute, Hyogo 679-5198 Japan

T. Usui15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

S. Wada8,

8Natural History Sciences, IIL, Hokkaido University, Sapporo 001-0021, Japan

M. Wadhwa40,

40School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA

R.J. Walker41,

41Geology, University of Maryland, College Park, MD 20742, USA

K. Yamashita42,

42Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan

Q.-Z. Yin43,

43Earth and Planetary Sciences, University of California, Davis, CA 95616, USA

S. Yoneda44,

44Science and Engineering, National Museum of Nature and Science, Tsukuba 305-0005, Japan

E.D. Young28,

28Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095, USA

H. Yui45,

45Chemistry, Tokyo University of Science, Tokyo 162-8601, Japan

A.-C. Zhang46,

46School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China

T. Nakamura47,

47Department of Earth Science, Tohoku University, Sendai, 980-8578, Japan

H. Naraoka48,

48Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 819-0395, Japan

T. Noguchi24,

24Kochi Institute for Core Sample Research, JAMSTEC, Kochi 783-8502, Japan

R. Okazaki48,

48Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 819-0395, Japan

K. Sakamoto15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

H. Yabuta49,

49Earth and Planetary Systems Science Program, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan

M. Abe15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

A. Miyazaki15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

A. Nakato15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

M. Nishimura15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

T. Okada15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

T. Yada15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

K. Yogata15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

S. Nakazawa15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

T. Saiki15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

S. Tanaka15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

F. Terui51,

51UTokyo Organization for Planetary and Space Science, University of Tokyo, Tokyo 113-0033, Japan

Y. Tsuda15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

S.-I. Watanabe17,

17Earth and Planetary Sciences, Nagoya University, Nagoya 464-8601, Japan

M. Yoshikawa15,

15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan

S. Tachibana51,

51UTokyo Organization for Planetary and Space Science, University of Tokyo, Tokyo 113-0033, Japan

H. Yurimoto8

8Natural History Sciences, IIL, Hokkaido University, Sapporo 001-0021, Japan

Affiliations | Corresponding Author | Cite as | Funding information

F. Moynier
Email: moynier@ipgp.fr

1Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France
2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
3Graduate School of Engineering Materials Science and Engineering, Tokyo Denki University, Tokyo 120-8551, Japan
4Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, Museum National d’Histoire Naturelle, CNRS UMR 7590, IRD, 75005 Paris, France
5Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, 20015, USA
6McDonnell Center for the Space Sciences and Physics Department, Washington University, St. Louis, MO 63130, USA
7Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, GD 510640, China
8Natural History Sciences, IIL, Hokkaido University, Sapporo 001-0021, Japan
9Centre for Star and Planet Formation, GLOBE Institute, University of Copenhagen, Copenhagen, K 1350, Denmark
10Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth 95447, Germany
11Department of Earth Science Education, Seoul National University, Seoul 08826, Republic of Korea
12Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago 60637, USA
13Faculty of Geosciences and Geography, University of Göttingen, Göttingen, D-37077, Germany
14Faculty of Science, Ibaraki University, Mito 310-8512, Japan
15ISAS/JSEC, JAXA, Sagamihara 252-5210, Japan
16General Systems Studies, The University of Tokyo, Tokyo 153-0041, Japan
17Earth and Planetary Sciences, Nagoya University, Nagoya 464-8601, Japan
18Osaka Application Laboratory, SBUWDX, Rigaku Corporation, Osaka 569-1146, Japan
19Max Planck Institute for Chemistry, Mainz 55128, Germany.
20Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
21Analytical Technology, Horiba Techno Service Co., Ltd., Kyoto 601-8125, Japan
22Earth and Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan
23School of Earth and Environmental Sciences, The University of Queensland, St Lucia QLD 4072, Australia
24Kochi Institute for Core Sample Research, JAMSTEC, Kochi 783-8502, Japan
25Earth and Planetary Sciences, Kyoto University, Kyoto 606-8502, Japan
26Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA
27Max Planck Institute for Solar System Research; 37077 Göttingen, Germany
28Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095, USA
29Thermal Analysis, Rigaku Corporation, Tokyo 196-8666, Japan
30Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
31Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, TX 77058, USA
32Earth-System Sciences, Korea Polar Research Institute, Incheon 21990, Korea
33Centre de Recherches Pétrographiques et Géochimiques, CNRS - Université de Lorraine, 54500 Nancy, France
34University of Science and Technology of China, School of Earth and Space Sciences, Anhui 230026, China
35Department of Earth Sciences, Natural History Museum, London, SW7 5BD, UK
36IIL, Hokkaido University, Sapporo 001-0021, Japan
37Institute for Geochemistry and Petrology, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland
38Earth and Space Science, Osaka University, Osaka 560-0043, Japan
39Spectroscopy and Imaging, Japan Synchrotron Radiation Research Institute, Hyogo 679-5198 Japan
40School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA
41Geology, University of Maryland, College Park, MD 20742, USA
42Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
43Earth and Planetary Sciences, University of California, Davis, CA 95616, USA
44Science and Engineering, National Museum of Nature and Science, Tsukuba 305-0005, Japan
45Chemistry, Tokyo University of Science, Tokyo 162-8601, Japan
46School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
47Department of Earth Science, Tohoku University, Sendai, 980-8578, Japan
48Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 819-0395, Japan
49Earth and Planetary Systems Science Program, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan
50Kanagawa Institute of Technology, Atsugi 243-0292, Japan
51UTokyo Organization for Planetary and Space Science, University of Tokyo, Tokyo 113-0033, Japan

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.-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., 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., 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.-I., Yoshikawa, M., Tachibana, S., Yurimoto, H. (2022) The Solar System calcium isotopic composition inferred from Ryugu samples. Geochem. Persp. Let. 24, 1–6. https://doi.org/10.7185/geochemlet.2238

IPGP analytical platform PARI, Ile-de-France SESAME Grants 12015908, DIM ACAV+, ERC grant 101001282 (METAL), Labex UnivEarth (FM), JSPS Kaken-hi grants (ST, HY, TY), and the CNES.

Geochemical Perspectives Letters v24 | https://doi.org/10.7185/geochemlet.2238
Received 28 June 2022 | Accepted 19 September 2022 | Published 19 October 2022

Copyright © 2022 The Authors

Published by the European Association of Geochemistry
under Creative Commons License CC BY-NC-ND 4.0

Keywords: asteroid, solar system, calcium, isotopes, Ryugu, Hayabusa2, alteration, carbonates

PDF PDF+SI
  • Share this article

  • Article views:
    581

    Cumulative count of HTML views and PDF downloads.

  • Download Citation
  • Rights & Permissions


top

Abstract

Abstract | Introduction | Samples and Methods | Results and Discussion | Acknowledgements | References | Supplementary Information

The Hayabusa2 spacecraft has returned samples from the Cb-type asteroid (162173) Ryugu to Earth. Previous petrological and chemical analyses support a close link between Ryugu and CI chondrites that are presumed to be chemically the most primitive meteorites with a solar-like composition. However, Ryugu samples are highly enriched in Ca compared to typical CI chondrites. To identify the cause of this discrepancy, here we report stable Ca isotopic data (expressed as δ44/40CaSRM915a) for returned Ryugu samples collected from two sites. We found that samples from both sites have similar δ44/40CaSRM915a (0.58 ± 0.03 ‰ and 0.55 ± 0.08 ‰, 2 s.d.) that fall within the range defined by CIs. This isotopic similarity suggests that the Ca budget of CIs and Ryugu samples is dominated by carbonates, and the variably higher Ca contents in Ryugu samples are due to the abundant carbonates. Precipitation of carbonates on Ryugu likely coincided with a major episode of aqueous activity dated to have occurred ∼5 Myr after Solar System formation. Based on the pristine Ryugu samples, the average δ44/40CaSRM915a of the Solar System is defined to be 0.57 ± 0.04 ‰ (2 s.d.).

Figures and Tables

Figure 1 The δ44/42Ca values plotted against δ44/40Ca values for the various samples analysed in this study, including the Ryugu samples. All the samples fall on a mass dependent line within error. Error bars represent 2 sigma standard deviation.

Figure 2 A comparison of age corrected δ44/40Ca values for the samples analysed here (in colour, see Fig. 1) and from the literature (grey). Ryugu samples from Chambers A and C are similar within error and fall within the range defined by the CI chondrites. The literature data are from Table 1, BSE estimate from Kang et al. (2017) and chondrules data from Amsellem et al. (2017). Error bars are 2 x standard deviation.

Figure 3 δ44/40Ca plotted against the Ca/Al ratio of the samples. The Ca/Al ratios of bulk Chamber A and Chamber C samples from Yokoyama et al. (2022) are used for Ryugu samples in this work and are taken from the average value in Barrat et al. (2012) for Orgueil, as it was not available for specific samples used here.

Table 1 Calcium isotopic data from this study and literature (Simon and DePaolo, 2010; Valdes et al., 2014; Amsellem et al., 2017; Huang and Jacobsen, 2017). 2 s.d. = 2 x standard deviation and 2 s.e. = 2 x standard error (2sd/√n). n is number of measurements.

Figure 1 Figure 2 Figure 3 Table 1

View all figures and tables





top

Introduction

Abstract | Introduction | Samples and Methods | Results and Discussion | Acknowledgements | References | Supplementary Information


In December 2020, the JAXA Hayabusa2 spacecraft returned to Earth with the first samples collected from a Cb-type asteroid, (162173) Ryugu (Tachibana et al., 2022

Tachibana, S., Sawada, H., Okazaki, R., Takano, Y., Sakamoto, K. et al. (2022) Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth. Science 375, 1011–1016. https://doi.org/10.1126/science.abj8624

; Yada et al., 2022

Yada, T., Abe, M., Okada, T., Nakato, A., Yogata, K. et al. (2022) Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu. Nature Astronomy 6, 214–220. https://doi.org/10.1038/s41550-021-01550-6

). Chemical, mineralogical, petrological, and isotopic analyses of these samples suggest that they are closely related to CI chondrites. In particular, their bulk Cr and Ti isotopic signatures and the chemical abundances of most elements are within the range of CI chondrites (Nakamura E. et al., 2022

Nakamura, E., Kobayashi, K., Tanaka, R., Kunihiro, T., Kitagawa, H. et al. (2022) On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective. Proceedings of the Japan Academy, Series B. 6, 227–282. https://doi.org/10.2183/pjab.98.015

; Yokoyama et al., 2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

). Among meteorites, CI chondrites have chemical compositions that most closely resemble the Sun; therefore, they are the most representative samples of the solar nebula composition with the exception of volatile elements (Palme et al., 2014

Palme, H., Lodders, K., Jones, A. (2014) 2.2 - Solar System abundances of the elements. In: Holland, H.D., Turekian, K.K. (Exec. Eds.) Treatise on Geochemistry (Second Edition). Elsevier, Oxford, 15–36. https://doi.org/10.1016/B978-0-08-095975-7.00118-2

). Given that the Ryugu samples did not experience any terrestrial alteration, they are likely the chemically most pristine Solar System samples available estimating the original isotopic compositions of most elements in the Solar System (Yokoyama et al., 2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

).

Despite many aspects of similarities with the CIs, the Ryugu samples display an apparent excess of Ca by over 50 %, which may be related to a heterogeneous distribution of carbonates (dolomite and calcite) (Nakamura T. et al., 2022

Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M. et al. (2022) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science. https://doi.org/10.1126/science.abn8671

; Yokoyama et al., 2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

) between Ryugu, Orgueil and other CIs. Calcium is a major constituent of carbonates and can be isotopically fractionated during aqueous alteration and carbonate precipitation, leading to more than 1 ‰ variations in the 44Ca/40Ca ratio in terrestrial carbonates (e.g., Fantle and Tipper, 2014

Fantle, M.S., Tipper, E.T. (2014) Calcium isotopes in the global biogeochemical Ca cycle: Implications for development of a Ca isotope proxy. Earth-Science Reviews 129, 148–177. https://doi.org/10.1016/j.earscirev.2013.10.004

; Blättler and Higgins, 2017

Blättler, C., Higgins, J. (2017) Testing Urey’s carbonate–silicate cycle using the calcium isotopic composition of sedimentary carbonates. Earth and Planetary Science Letters 479, 241–251. https://doi.org/10.1016/j.epsl.2017.09.033

). In addition, Ca exhibits large isotopic variations among bulk carbonaceous chondrites (CC), with the 44Ca/40Ca ratio spanning a range of 1 ‰. This range is likely related to a combination of the variable modal abundances of refractory inclusions among CC (Hezel et al., 2008

Hezel, DC., Russell, S.S., Ross, A.J., Kearsley, A.T. (2008) Modal Abundances of CAIs: Implications for bulk chondrite element abundances and fractionations. Meteoritics & Planetary Science 43, 1879–1894. https://doi.org/10.1111/j.1945-5100.2008.tb00649.x

) that can be enriched in the lighter Ca isotopes by several per mille (Niederer and Papanastassiou, 1984

Niederer, F.R., Papanastassiou, D.A. (1984) Ca isotopes in refractory inclusions. Geochimica et Cosmochimica Acta 48, 1279–1293. https://doi.org/10.1016/0016-7037(84)90062-0

; Huang et al., 2012

Huang, S., Farkas, J., Yu, G., Petaev, M.I., Jacobsen, S.B. (2012) Calcium isotopic ratios and rare earth elements abundances from refractory inclusions from the Allende CV3 chondrite. Geochimica et Cosmochimica Acta 77, 252–265. https://doi.org/10.1016/j.gca.2011.11.002

) and the heterogeneous distribution of carbonates (Simon and DePaolo, 2010

Simon, J.I., DePaolo, D.J. (2010) Stable calcium isotopic composition of meteorites and rocky planets. Earth and Planetary Science Letters 289, 457–466. https://doi.org/10.1016/j.epsl.2009.11.035

; Valdes et al., 2014

Valdes, M., Moreira, M., Foriel, J., Moynier, F. (2014) The nature of Earth’s building blocks as revealed by calcium isotopes. Earth and Planetary Science Letters 394, 135–145. https://doi.org/10.1016/j.epsl.2014.02.052

; Dauphas and Pourmand, 2015

Dauphas, N., Pourmand, A. (2015) Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect. Geochimica et Cosmochimica Acta 163, 234–261. https://doi.org/10.1016/j.gca.2015.03.037

). Therefore, stable Ca isotopes could be useful for investigating the origin of Ca excess in Ryugu samples compared to CIs.

Here we have analysed the stable Ca isotopic compositions of Ryugu samples collected from the first and second touchdown sites, using the collision cell equipped multicollection inductively-coupled plasma mass spectrometer (CC-MC-ICP-MS), Nu Sapphire.

top

Samples and Methods

Abstract | Introduction | Samples and Methods | Results and Discussion | Acknowledgements | References | Supplementary Information


The samples returned by the Hayabusa2 spacecraft consist of ∼5 g of materials from the Ryugu asteroid recovered during two touchdowns (Tachibana et al., 2022

Tachibana, S., Sawada, H., Okazaki, R., Takano, Y., Sakamoto, K. et al. (2022) Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth. Science 375, 1011–1016. https://doi.org/10.1126/science.abj8624

; Yada et al., 2022

Yada, T., Abe, M., Okada, T., Nakato, A., Yogata, K. et al. (2022) Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu. Nature Astronomy 6, 214–220. https://doi.org/10.1038/s41550-021-01550-6

). Approximately 3 g of samples representing the surface materials of Ryugu were collected during the first touchdown and stored in Chamber A. Approximately 2 g of samples likely representing a mixture of materials from the surface and subsurface were collected into Chamber C at a site that was close to the crater formed by the Small Carry-on Impactor, a kinetic impact experiment of the Hayabusa2 mission (Saiki et al., 2017

Saiki, S., Imamura, H., Arakawa, M., Wada, K., Takagi, Y., Hayakawa, M., Shirai, K., Yano, H., Okamoto, C. (2017) The Small Carry-on Impactor (SCI) and the Hayabusa2 Impact Experiment. Space Science Reviews 208, 165–186. https://doi.org/10.1007/s11214-016-0297-5

; Arakawa et al., 2020

Arakawa, M., Saiki, T., Wada, K., Ogawa, K., Kadono, T. et al. (2020) An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime. Science 368, 67–71. https://doi.org/10.1126/science.aaz1701

). Two Ryugu samples, A0106-A0107 (Chamber A) and C0108 (Chamber C), were analysed in this study (for information on the mineralogy see https://jaxa.repo.nii.ac.jp/?action=repository_uri&item_id=48255&file_id=31&file_no=1).

Sample A0106-A0107 was prepared from a mixed aggregate of A0106 (1.6 mg) and A0107 (27.3 mg). In addition to the Ryugu samples, fusion-crust free bulk samples of six CC, Orgueil (CI1), Alais (CI1), Tarda (C2-ungrouped), Tagish Lake (C2-ungrouped), Murchison (CM2), and Allende (CV3), were analysed in the same way for comparison. See Table S-1 for the weights and providers of the meteorite samples. All samples were dissolved in PFA vials with a mixture of concentrated HF and HNO3 at the Tokyo Institute of Technology (Yokoyama et al., 2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

).

After dissolution, aliquots of ∼0.15 % of the solutions containing ∼5 μg of Ca were transferred and dedicated for our study. All the sample aliquots were dried and redissolved in 0.4 ml of 4 mol/L HNO3 in preparation for Ca chemical purification and isotopic measurements at the Institut de Physique du Globe, following Dai et al.

Dai, W., Moynier, F., Paquet, M., Moureau, J., Debret, B., Siebert, J., Gerard, Y., Zhao, Y. (2021) Calcium isotope measurements using a collision cell (CC)-MC-ICP-MS. Chemical Geology 590, 120688. https://doi.org/10.1016/j.chemgeo.2021.120688

(2022

Dai, W., Moynier, F., Paquet, M., Moureau, J., Debret, B., Siebert, J., Gerard, Y., Zhao, Y. (2021) Calcium isotope measurements using a collision cell (CC)-MC-ICP-MS. Chemical Geology 590, 120688. https://doi.org/10.1016/j.chemgeo.2021.120688

) (see Supplementary Information).

We report both the mass dependent deviation and the radiogenic ingrowth on 40Ca from the decay of 40K. For mass dependent deviation, the data are reported as δx/yCa:




with x and y = 40, 42, 43 or 44. Since most of the published Ca isotope data are measured against the SRM 915a standard, the δ44/40Ca values reported here are re-normalised to SRM915a to facilitate comparison.

The radiogenic ingrowth on 40Ca is reported using the epsilon notation,




with (40Ca/44Ca)n representing the 40Ca/44Ca ratio corrected from the mass dependent isotopic fractionation after being normalised to the 42Ca/44Ca ratio using the exponential law and 42Ca/44Ca = 0.31221 (Russell et al., 1978

Russell, W.A., Papanastassiou, D.A., Tombrello, T.A. (1978) Ca isotope fractionation on the Earth and other solar system materials. Geochimica et Cosmochimica Acta 42, 1075–1090. https://doi.org/10.1016/0016-7037(78)90105-9

).

The effect of concentration mismatch on the Sapphire is more significant than on traditional MC-ICP-MS (Moynier et al., 2021

Moynier, F., Hu, Y., Wang, K., Zhao, Y., Gérard, Y., Deng, Z., Moureau, J., Li, W., Simon, J.I., Teng, F.-Z. (2021) Potassium isotopic composition of various samples using a dual-path collision-cell-capable multiple-collector inductively coupled plasma mass spectrometer. Chemical Geology 571, 120144. https://doi.org/10.1016/j.chemgeo.2021.120144

), and all the samples were analysed with Ca concentrations within 1 % of the standard.

top

Results and Discussion

Abstract | Introduction | Samples and Methods | Results and Discussion | Acknowledgements | References | Supplementary Information


The Ca isotopic compositions of the two Ryugu samples and the six CC are reported in Table 1, along with literature values for the chondrites where available. The radiogenic ingrowth on 40Ca from 40K decay was corrected using the K and Ca abundances of the samples (from Yokoyama et al., 2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

) and δ44/40Ca (age corrected) ratios are also presented in Table 1. The following discussion focuses on these corrected mass dependent isotopic variations. The δ44/40Ca difference between SRM915b and SRM915a is 0.72 ‰ (Heuser and Eisenhauer, 2008

Heuser, A., Eisenhauer, A. (2008) The calcium isotope composition (delta Ca-44/40) of NIST SRM 915b and NIST SRM 1486. Geostandards and Geoanalytical Research 32, 311–315. https://doi.org/10.1111/j.1751-908X.2008.00877.x

). Neither the Ryugu samples nor the meteorites analysed here show any 40Ca anomalies (after age corrections), which is consistent with the literature (e.g., Simon and DePaolo, 2010

Simon, J.I., DePaolo, D.J. (2010) Stable calcium isotopic composition of meteorites and rocky planets. Earth and Planetary Science Letters 289, 457–466. https://doi.org/10.1016/j.epsl.2009.11.035

; Huang and Jacobsen, 2017

Huang, S., Jacobsen, S.B. (2017) Calcium isotopic compositions of chondrites. Geochimica et Cosmochimica Acta 201, 364–376. https://doi.org/10.1016/j.gca.2016.09.039

).

Table 1 Calcium isotopic data from this study and literature (Simon and DePaolo, 2010

Simon, J.I., DePaolo, D.J. (2010) Stable calcium isotopic composition of meteorites and rocky planets. Earth and Planetary Science Letters 289, 457–466. https://doi.org/10.1016/j.epsl.2009.11.035

; Valdes et al., 2014

Valdes, M., Moreira, M., Foriel, J., Moynier, F. (2014) The nature of Earth’s building blocks as revealed by calcium isotopes. Earth and Planetary Science Letters 394, 135–145. https://doi.org/10.1016/j.epsl.2014.02.052

; Amsellem et al., 2017

Amsellem, E., Moynier, F., Pringle, E., Bouvier, A., Chen, H., Day, J.M.D. (2017) Testing the chondrule-rich accretion model for planetary embryos using calcium isotopes. Earth and Planetary Science Letters 469, 75–83. https://doi.org/10.1016/j.epsl.2017.04.022

; Huang and Jacobsen, 2017

Huang, S., Jacobsen, S.B. (2017) Calcium isotopic compositions of chondrites. Geochimica et Cosmochimica Acta 201, 364–376. https://doi.org/10.1016/j.gca.2016.09.039

). 2 s.d. = 2 x standard deviation and 2 s.e. = 2 x standard error (2sd/√n). n is number of measurements.
Sample namesδ40/44CaSRM915b2 s.d.δ42/44CaSRM915b2 s.d.δ43/44CaSRM915b2 s.d.ϵ40Ca2 s.enδ44/40CaSRM915aδ44/40CaSRM915a
(age corrected)
Ryugu C01080.220.030.120.030.040.07−0.170.2550.500.58
Ryugu A0106-A01070.230.080.110.050.060.070.090.2260.490.55
Murchison0.120.070.020.070.010.100.850.4650.600.67
Murchison (Valdes+) 0.84
Murchison (Huang+.) 0.72
Allende0.360.050.100.080.060.131.470.7940.360.39
Allende (Simon+) 0.52 0.58 2 0.49 0.54
Allende (Valdes+) 0.55
Allende (Amsellem+) 0.26
Allende (Amsellem+) 0.10
Allende (Amsellem+) 0.44
Allende (Huang+) 0.28
Alais0.410.060.170.060.100.080.560.3460.310.42
Tarda0.340.060.150.070.050.070.250.3760.380.45
Tagish Lake0.300.030.130.030.060.070.330.2660.420.48
Orgueil0.300.040.130.020.060.080.440.4040.420.48
Orgueil (Amsellem+) 0.45
Orgueil (Valdes+) 0.65
Orgueil (Huang+)0.75


In a plot of δ44/42Ca vs. δ44/40Ca (age corrected), the data fall along a mass dependent line, regardless of whether the slope for equilibrium fractionation (1/2.1 as shown in Fig. 1) or kinetic fractionation is used. Likewise, variations between δ44/42Ca and δ44/43Ca are mass dependent within error (Fig. S-2). Therefore, the Ca isotopic variations observed among the samples analysed primarily reflect mass dependent isotopic fractionation.


Figure 1 The δ44/42Ca values plotted against δ44/40Ca values for the various samples analysed in this study, including the Ryugu samples. All the samples fall on a mass dependent line within error. Error bars represent 2 sigma standard deviation.
Full size image


The meteorite data reported here are consistent with literature values (Fig. 2 and Table 1), but it should be noted that literature Ca isotopic values are variable, especially for Orgueil and Allende. The variability may reflect interlaboratory bias, but more likely it reflects isotopic heterogeneity at the sample scale analysed. This is particularly the case for Allende, which contains abundant calcium-aluminum-rich inclusions (CAIs). Since our Allende sample was obtained from the Smithsonian Museum’s large batch of homogenised powder, and our measured Ca isotopic composition falls in the middle of the range previously reported, it is likely representative of the bulk (Fig. 2). For Orgueil, part of the interlaboratory variability may be controlled by the variable distribution of secondary phases produced by aqueous alteration since Ca may be isotopically fractionated during alteration and carbonate precipitation (Blättler and Higgins, 2017

Blättler, C., Higgins, J. (2017) Testing Urey’s carbonate–silicate cycle using the calcium isotopic composition of sedimentary carbonates. Earth and Planetary Science Letters 479, 241–251. https://doi.org/10.1016/j.epsl.2017.09.033

). However, none of the studies that report Ca isotopic data include the Ca contents of their Orgueil analyses. We report here the first δ44/40Ca values for Tarda and Tagish Lake, which are within error of one another and overlap with Orgueil.


Figure 2 A comparison of age corrected δ44/40Ca values for the samples analysed here (in colour, see Fig. 1) and from the literature (grey). Ryugu samples from Chambers A and C are similar within error and fall within the range defined by the CI chondrites. The literature data are from Table 1, BSE estimate from Kang et al. (2017)

Kang, J.T., Ionov, D.A., Liu, F., Zhang, C.L., Golovin, A.V., Qin, L.-P., Zhang, Z.-F., Huang, F. (2017) Calcium isotopic fractionation in mantle peridotites by melting and metasomatism and Ca isotope composition of the Bulk Silicate Earth. Earth and Planetary Science Letters 474, 128–137. https://doi.org/10.1016/j.epsl.2017.05.035

and chondrules data from Amsellem et al. (2017)

Amsellem, E., Moynier, F., Pringle, E., Bouvier, A., Chen, H., Day, J.M.D. (2017) Testing the chondrule-rich accretion model for planetary embryos using calcium isotopes. Earth and Planetary Science Letters 469, 75–83. https://doi.org/10.1016/j.epsl.2017.04.022

. Error bars are 2 x standard deviation.
Full size image


The two Ryugu samples have Ca isotopic compositions within error of one another (δ44/40Ca = 0.58 ± 0.03 ‰ for C0108 and 0.55 ± 0.08 ‰ for A0106-A0107; uncertainties represent 2 s.e. for n = 5 and 6, respectively). They are also within the range of published δ44/40Ca values for CIs (Fig. 2). Notably, Ryugu sample A0106-A0107 (Ca/Al ∼ 1.9) has almost twice the amount of Ca compared to the average CI (Ca/Al ∼ 1.06) (Fig. 3), and ∼20 % more than Ryugu sample C0108 (Ca/Al ∼ 1.55). If the excess Ca in A0106-A0107 is mainly stored in secondary carbonates (Yokoyama et al., 2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

and our discussion below), then these carbonates must contribute significantly to the bulk Ca isotopic composition. Therefore, our results imply that the Ca isotopic composition of the Ryugu samples and CIs are not significantly modified by the dissolution of primary Ca-bearing phases and precipitation as carbonates during aqueous alteration. One reason for the similar Ca isotopic compositions in Ryugu samples and CIs is that their Ca isotopic compositions are mostly dominated by the high abundance and the composition of the carbonates.


Figure 3 δ44/40Ca plotted against the Ca/Al ratio of the samples. The Ca/Al ratios of bulk Chamber A and Chamber C samples from Yokoyama et al.

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

(2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

) are used for Ryugu samples in this work and are taken from the average value in Barrat et al.

Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C. et al. (2012) Geochemistry of CI chondrites: Major and trace elements, and Cu and Zn Isotopes. Geochimica et Cosmochimica Acta 83, 79–92. https://doi.org/10.1016/j.gca.2011.12.011

(2012

Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C. et al. (2012) Geochemistry of CI chondrites: Major and trace elements, and Cu and Zn Isotopes. Geochimica et Cosmochimica Acta 83, 79–92. https://doi.org/10.1016/j.gca.2011.12.011

) for Orgueil, as it was not available for specific samples used here.
Full size image


Several studies have quantified the modal abundances of minerals in CIs, but there is no systematic study and consensus on the Ca carriers. Calcium sulfates are usually not detected in CIs but can be present at up to ∼1 vol. % (e.g., Endress and Bischoff, 1996

Endress, M., Bishoff, A. (1996) Carbonates in CI chondrites: Clues to parent body evolution. Geochimica et Cosmochimica Acta 60, 489–507. https://doi.org/10.1016/0016-7037(95)00399-1

; Morlok, et al., 2006

Morlok, A., Bischoff, A., Stephan, T., Floss, C., Zinner, E., Jessberger, E.K. (2006) Brecciation and chemical heterogeneities of CI chondrites. Geochimica et Cosmochimica Acta 70, 5371–5394. https://doi.org/10.1016/j.gca.2006.08.007

). Even when present, they were suggested to have formed during terrestrial alteration (Gounelle and Zolensky, 2001

Gounelle, M., Zolensky, M. (2001) A terrestrial origin for sulfate veins in CI1 chondrites. Meteoritics & Planetary Science. 36, 1321–1329. https://doi.org/10.1111/j.1945-5100.2001.tb01827.x

). Ca-rich phosphates exist in CI chondrites (Morlok et al., 2006

Morlok, A., Bischoff, A., Stephan, T., Floss, C., Zinner, E., Jessberger, E.K. (2006) Brecciation and chemical heterogeneities of CI chondrites. Geochimica et Cosmochimica Acta 70, 5371–5394. https://doi.org/10.1016/j.gca.2006.08.007

), but they appear to be quite rare (0–0.05 vol. %; King et al., 2015

King, A., Schofield, P.F., Howard, K., Russell, S.S. (2015) Modal mineralogy of CI and CI-like chondrites by X-ray diffraction. Geochimica et Cosmochimica Acta 165, 148–160. https://doi.org/10.1016/j.gca.2015.05.038

; Alfing et al., 2019

Alfing, J., Patsek, M., Bischoff, A. (2019) Geochemistry Modal abundances of coarse-grained (>5μm) components within CI-chondrites and their individual clasts - Mixing of various lithologies on the CI parent body(ies). Geochemistry 39, 3–16. https://doi.org/10.1016/j.chemer.2019.08.004

) and therefore are unlikely to have a strong control on the total Ca budget. Thus, carbonates are the most likely major carriers of Ca in CIs (Endress and Bischoff, 1996

Endress, M., Bishoff, A. (1996) Carbonates in CI chondrites: Clues to parent body evolution. Geochimica et Cosmochimica Acta 60, 489–507. https://doi.org/10.1016/0016-7037(95)00399-1

; Morlok et al., 2006

Morlok, A., Bischoff, A., Stephan, T., Floss, C., Zinner, E., Jessberger, E.K. (2006) Brecciation and chemical heterogeneities of CI chondrites. Geochimica et Cosmochimica Acta 70, 5371–5394. https://doi.org/10.1016/j.gca.2006.08.007

, Alfing et al., 2019

Alfing, J., Patsek, M., Bischoff, A. (2019) Geochemistry Modal abundances of coarse-grained (>5μm) components within CI-chondrites and their individual clasts - Mixing of various lithologies on the CI parent body(ies). Geochemistry 39, 3–16. https://doi.org/10.1016/j.chemer.2019.08.004

). Scanning electron microscopic (SEM) analyses of 18 sections of CIs (including Orgueil) point to an average carbonate abundance of ∼5 vol. % and the carbonates are dominated by dolomite (Endress and Bischoff, 1996

Endress, M., Bishoff, A. (1996) Carbonates in CI chondrites: Clues to parent body evolution. Geochimica et Cosmochimica Acta 60, 489–507. https://doi.org/10.1016/0016-7037(95)00399-1

). However, analyses of CO2 released by phosphoric acid dissolution of ∼100 mg of Orgueil only returned ∼0.1 wt. % of carbonate C (Alexander et al., 2015

Alexander, C.M.O’D., Bowden, R., Fogel, M.L., Howard, K. (2015) Carbonate abundances and isotopic compositions in chondrites. Meteoritics & Planetary Science 50, 810–833. https://doi.org/10.1111/maps.12410

), which is equivalent to ∼0.8 wt. % carbonate (although carbonate abundance in Ivuna estimated by a similar method is three times higher). X-ray diffraction (detection limit ∼1 vol. %) did not reveal carbonates in three Orgueil samples (from 50 to 200 mg), but 2 vol. % in Alais (200 mg) and 3 vol. % in Ivuna (50 mg) (King et al., 2015

King, A., Schofield, P.F., Howard, K., Russell, S.S. (2015) Modal mineralogy of CI and CI-like chondrites by X-ray diffraction. Geochimica et Cosmochimica Acta 165, 148–160. https://doi.org/10.1016/j.gca.2015.05.038

), while Bland et al.

Bland, P., Cressey, G., Menzies, O. (2010) Modal mineralogy of carbonaceous chondrites by X-ray diffraction and Mossbauer spectroscopy. Meteoritics and Planetary Science 39, 3–16. https://doi.org/10.1111/j.1945-5100.2004.tb00046.x

(2004

Bland, P., Cressey, G., Menzies, O. (2010) Modal mineralogy of carbonaceous chondrites by X-ray diffraction and Mossbauer spectroscopy. Meteoritics and Planetary Science 39, 3–16. https://doi.org/10.1111/j.1945-5100.2004.tb00046.x

) detected no carbonates in Orgueil (200–300 mg samples). Given the variability in the modal mineralogy in the literature, Alfing et al.

Alfing, J., Patsek, M., Bischoff, A. (2019) Geochemistry Modal abundances of coarse-grained (>5μm) components within CI-chondrites and their individual clasts - Mixing of various lithologies on the CI parent body(ies). Geochemistry 39, 3–16. https://doi.org/10.1016/j.chemer.2019.08.004

(2009

Alfing, J., Patsek, M., Bischoff, A. (2019) Geochemistry Modal abundances of coarse-grained (>5μm) components within CI-chondrites and their individual clasts - Mixing of various lithologies on the CI parent body(ies). Geochemistry 39, 3–16. https://doi.org/10.1016/j.chemer.2019.08.004

) focused on phases >5 μm (which only represent ∼6 vol. % of CIs) and found ∼0.5 wt. % of carbonates in CIs. A variability in the abundance of carbonates in CIs is consistent with variable Ca concentrations (from 0.77 to 0.96 wt. %) measured even in large (0.5–1 g) Orgueil bulk samples (Barrat et al., 2012

Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C. et al. (2012) Geochemistry of CI chondrites: Major and trace elements, and Cu and Zn Isotopes. Geochimica et Cosmochimica Acta 83, 79–92. https://doi.org/10.1016/j.gca.2011.12.011

). Considering that the most abundant carbonates in Orgueil are dolomites with ∼20 wt. % Ca (Endress and Bishoff, 1996

Endress, M., Bishoff, A. (1996) Carbonates in CI chondrites: Clues to parent body evolution. Geochimica et Cosmochimica Acta 60, 489–507. https://doi.org/10.1016/0016-7037(95)00399-1

), the presence of ∼4 wt. % carbonates in CIs would be sufficient to dominate their Ca budget, less if calcites or aragonites are involved. Despite the variability in carbonate abundances of CIs reported in the literature, we suggest that the major fraction of Ca in CIs is stored in carbonates.

Nakamura, T. et al.

Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M. et al. (2022) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science. https://doi.org/10.1126/science.abn8671

(2022

Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M. et al. (2022) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science. https://doi.org/10.1126/science.abn8671

) estimated the mineral abundances and compositions of the main phases of the Ryugu samples by SEM observations of two ∼10 mm2 sections from a sample from the second touchdown site (sample C0002) (see their Tables S6 and S7). No Ca sulfates were found in these sections, and a simple mass balance using their data shows that carbonates account for 75–80 % of the Ca budget, with apatite and phyllosilicates accommodating the remaining Ca more or less equally. This calculation may underestimate the Ca fraction in carbonates because the samples also contain small Ca carbonate grains (e.g., Table S7 of Nakamura T. et al., 2022

Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M. et al. (2022) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science. https://doi.org/10.1126/science.abn8671

), the abundances of which could not be quantified here. C0002 is the third largest sample among all returned grains containing the major lithology (Nakamura T. et al., 2022

Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M. et al. (2022) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science. https://doi.org/10.1126/science.abn8671

), suggesting that the Ca budget in the Ryugu samples is dominated by carbonates. It should be noted that another study also found several vol. % of carbonate minerals in samples from both touchdown sites, with a large variability in Ca content between ∼1 mg grains (Nakamura E. et al., 2022

Nakamura, E., Kobayashi, K., Tanaka, R., Kunihiro, T., Kitagawa, H. et al. (2022) On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective. Proceedings of the Japan Academy, Series B. 6, 227–282. https://doi.org/10.2183/pjab.98.015

) and a correlation between Ca content and the dolomite abundances of the grains (Fig. S-1). The two heaviest Ca isotopic compositions for Orgueil samples from Valdes et al.

Valdes, M., Moreira, M., Foriel, J., Moynier, F. (2014) The nature of Earth’s building blocks as revealed by calcium isotopes. Earth and Planetary Science Letters 394, 135–145. https://doi.org/10.1016/j.epsl.2014.02.052

(2014

Valdes, M., Moreira, M., Foriel, J., Moynier, F. (2014) The nature of Earth’s building blocks as revealed by calcium isotopes. Earth and Planetary Science Letters 394, 135–145. https://doi.org/10.1016/j.epsl.2014.02.052

) (0.65 ± 0.17 ‰, 2 s.d.) and Huang and Jacobsen

Huang, S., Jacobsen, S.B. (2017) Calcium isotopic compositions of chondrites. Geochimica et Cosmochimica Acta 201, 364–376. https://doi.org/10.1016/j.gca.2016.09.039

(2017

Huang, S., Jacobsen, S.B. (2017) Calcium isotopic compositions of chondrites. Geochimica et Cosmochimica Acta 201, 364–376. https://doi.org/10.1016/j.gca.2016.09.039

) (0.75 ± 0.11 ‰, 2 s.d.) may reflect different proportions of carbonates. Unfortunately, these two studies did not report the Ca contents of their Orgueil fractions, so it is not possible to test this hypothesis.

The similar Ca isotopic compositions between the two Ryugu samples and CIs are most simply explained if the Ca excesses observed in the bulk Ryugu samples are due to the heterogeneous distribution of carbonates, and if these carbonates have similar Ca isotopic compositions to the bulk samples. This explanation is consistent with an episode of fluid circulation and carbonate precipitation in the Ryugu samples that occurred 2.5 to 5 Myr after CAIs formation, as dated using 53Mn-53Cr chronometry in carbonate phases (Nakamura E. et al., 2022

Nakamura, E., Kobayashi, K., Tanaka, R., Kunihiro, T., Kitagawa, H. et al. (2022) On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective. Proceedings of the Japan Academy, Series B. 6, 227–282. https://doi.org/10.2183/pjab.98.015

; Yokoyama et al., 2022

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

). Hence, at present the average of the two Ryugu samples (0.57 ± 0.04 ‰, 2 s.d.) represents the best estimate of Ryugu’s and Solar System Ca isotopic composition. Future work should test whether this value is representative of the whole body by analysing other Ryugu fragments containing fewer carbonate phases and less total Ca, such as the Ryugu material in section 5 from C0002 (Nakamura T. et al., 2022

Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M. et al. (2022) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science. https://doi.org/10.1126/science.abn8671

), which only contains ∼75 % of its Ca in carbonates.

top

Acknowledgements

Abstract | Introduction | Samples and Methods | Results and Discussion | Acknowledgements | References | Supplementary Information


This work was partly supported by the IPGP analytical platform PARI, Ile-de-France SESAME Grants 12015908, DIM ACAV+, the ERC grant 101001282 (METAL), Labex UnivEarth (FM), JSPS Kaken-hi grants (ST, HY, TY) and the CNES. We thank Dominik Hezel and one anonymous reviewer for constructive comments that helped improve the manuscript.

Editor: Anat Shahar

top

References

Abstract | Introduction | Samples and Methods | Results and Discussion | Acknowledgements | References | Supplementary Information

Alfing, J., Patsek, M., Bischoff, A. (2019) Geochemistry Modal abundances of coarse-grained (>5μm) components within CI-chondrites and their individual clasts - Mixing of various lithologies on the CI parent body(ies). Geochemistry 39, 3–16. https://doi.org/10.1016/j.chemer.2019.08.004
Show in context

Ca-rich phosphates exist in CI chondrites (Morlok et al., 2006), but they appear to be quite rare (0–0.05 vol. %; King et al., 2015; Alfing et al., 2019) and therefore are unlikely to have a strong control on the total Ca budget.
View in article
Thus, carbonates are the most likely major carriers of Ca in CIs (Endress and Bischoff, 1996; Morlok et al., 2006, Alfing et al., 2019).
View in article


Alexander, C.M.O’D., Bowden, R., Fogel, M.L., Howard, K. (2015) Carbonate abundances and isotopic compositions in chondrites. Meteoritics & Planetary Science 50, 810–833. https://doi.org/10.1111/maps.12410
Show in context

However, analyses of CO2 released by phosphoric acid dissolution of ∼100 mg of Orgueil only returned ∼0.1 wt. % of carbonate C (Alexander et al., 2015), which is equivalent to ∼0.8 wt. % carbonate (although carbonate abundance in Ivuna estimated by a similar method is three times higher).
View in article


Amsellem, E., Moynier, F., Pringle, E., Bouvier, A., Chen, H., Day, J.M.D. (2017) Testing the chondrule-rich accretion model for planetary embryos using calcium isotopes. Earth and Planetary Science Letters 469, 75–83. https://doi.org/10.1016/j.epsl.2017.04.022
Show in context

Calcium isotopic data from this study and literature (Simon and DePaolo, 2010; Valdes et al., 2014; Amsellem et al., 2017; Huang and Jacobsen, 2017).
View in article
The literature data are from Table 1, BSE estimate from Kang et al. (2017) and chondrules data from Amsellem et al. (2017). Error bars are 2 x standard deviation.
View in article


Arakawa, M., Saiki, T., Wada, K., Ogawa, K., Kadono, T. et al. (2020) An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime. Science 368, 67–71. https://doi.org/10.1126/science.aaz1701
Show in context

Approximately 2 g of samples likely representing a mixture of materials from the surface and subsurface were collected into Chamber C at a site that was close to the crater formed by the Small Carry-on Impactor, a kinetic impact experiment of the Hayabusa2 mission (Saiki et al., 2017; Arakawa et al., 2020).
View in article


Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C. et al. (2012) Geochemistry of CI chondrites: Major and trace elements, and Cu and Zn Isotopes. Geochimica et Cosmochimica Acta 83, 79–92. https://doi.org/10.1016/j.gca.2011.12.011
Show in context

The Ca/Al ratios of bulk Chamber A and Chamber C samples from Yokoyama et al. (2022) are used for Ryugu samples in this work and are taken from the average value in Barrat et al. (2012) for Orgueil, as it was not available for specific samples used here.
View in article
A variability in the abundance of carbonates in CIs is consistent with variable Ca concentrations (from 0.77 to 0.96 wt. %) measured even in large (0.5–1 g) Orgueil bulk samples (Barrat et al., 2012).
View in article


Bland, P., Cressey, G., Menzies, O. (2010) Modal mineralogy of carbonaceous chondrites by X-ray diffraction and Mossbauer spectroscopy. Meteoritics and Planetary Science 39, 3–16. https://doi.org/10.1111/j.1945-5100.2004.tb00046.x
Show in context

X-ray diffraction (detection limit ∼1 vol. %) did not reveal carbonates in three Orgueil samples (from 50 to 200 mg), but 2 vol. % in Alais (200 mg) and 3 vol. % in Ivuna (50 mg) (King et al., 2015), while Bland et al. (2004) detected no carbonates in Orgueil (200–300 mg samples).
View in article


Blättler, C., Higgins, J. (2017) Testing Urey’s carbonate–silicate cycle using the calcium isotopic composition of sedimentary carbonates. Earth and Planetary Science Letters 479, 241–251. https://doi.org/10.1016/j.epsl.2017.09.033
Show in context

Calcium is a major constituent of carbonates and can be isotopically fractionated during aqueous alteration and carbonate precipitation, leading to more than 1 ‰ variations in the 44Ca/40Ca ratio in terrestrial carbonates (e.g., Fantle and Tipper, 2014; Blättler and Higgins, 2017).
View in article
For Orgueil, part of the interlaboratory variability may be controlled by the variable distribution of secondary phases produced by aqueous alteration since Ca may be isotopically fractionated during alteration and carbonate precipitation (Blättler and Higgins, 2017).
View in article


Dai, W., Moynier, F., Paquet, M., Moureau, J., Debret, B., Siebert, J., Gerard, Y., Zhao, Y. (2021) Calcium isotope measurements using a collision cell (CC)-MC-ICP-MS. Chemical Geology 590, 120688. https://doi.org/10.1016/j.chemgeo.2021.120688
Show in context

All the sample aliquots were dried and redissolved in 0.4 ml of 4 mol/L HNO3 in preparation for Ca chemical purification and isotopic measurements at the Institut de Physique du Globe, following Dai et al. (2022) (see Supplementary Information).
View in article


Dauphas, N., Pourmand, A. (2015) Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect. Geochimica et Cosmochimica Acta 163, 234–261. https://doi.org/10.1016/j.gca.2015.03.037
Show in context

This range is likely related to a combination of the variable modal abundances of refractory inclusions among CC (Hezel et al., 2008) that can be enriched in the lighter Ca isotopes by several per mille (Niederer and Papanastassiou, 1984; Huang et al., 2012) and the heterogeneous distribution of carbonates (Simon and DePaolo, 2010; Valdes et al., 2014; Dauphas and Pourmand, 2015).
View in article


Endress, M., Bishoff, A. (1996) Carbonates in CI chondrites: Clues to parent body evolution. Geochimica et Cosmochimica Acta 60, 489–507. https://doi.org/10.1016/0016-7037(95)00399-1
Show in context

Calcium sulfates are usually not detected in CIs but can be present at up to ∼1 vol. % (e.g., Endress and Bischoff, 1996; Morlok, et al., 2006).
View in article
Thus, carbonates are the most likely major carriers of Ca in CIs (Endress and Bischoff, 1996; Morlok et al., 2006, Alfing et al., 2019).
View in article
Scanning electron microscopic (SEM) analyses of 18 sections of CIs (including Orgueil) point to an average carbonate abundance of ∼5 vol. % and the carbonates are dominated by dolomite (Endress and Bischoff, 1996).
View in article
Considering that the most abundant carbonates in Orgueil are dolomites with ∼20 wt. % Ca (Endress and Bishoff, 1996), the presence of ∼4 wt. % carbonates in CIs would be sufficient to dominate their Ca budget, less if calcites or aragonites are involved.
View in article


Fantle, M.S., Tipper, E.T. (2014) Calcium isotopes in the global biogeochemical Ca cycle: Implications for development of a Ca isotope proxy. Earth-Science Reviews 129, 148–177. https://doi.org/10.1016/j.earscirev.2013.10.004
Show in context

Calcium is a major constituent of carbonates and can be isotopically fractionated during aqueous alteration and carbonate precipitation, leading to more than 1 ‰ variations in the 44Ca/40Ca ratio in terrestrial carbonates (e.g., Fantle and Tipper, 2014; Blättler and Higgins, 2017).
View in article


Gounelle, M., Zolensky, M. (2001) A terrestrial origin for sulfate veins in CI1 chondrites. Meteoritics & Planetary Science. 36, 1321–1329. https://doi.org/10.1111/j.1945-5100.2001.tb01827.x
Show in context

Even when present, they were suggested to have formed during terrestrial alteration (Gounelle and Zolensky, 2001).
View in article


Heuser, A., Eisenhauer, A. (2008) The calcium isotope composition (delta Ca-44/40) of NIST SRM 915b and NIST SRM 1486. Geostandards and Geoanalytical Research 32, 311–315. https://doi.org/10.1111/j.1751-908X.2008.00877.x
Show in context

The following discussion focuses on these corrected mass dependent isotopic variations. The δ44/40Ca difference between SRM915b and SRM915a is 0.72 ‰ (Heuser and Eisenhauer, 2008).
View in article


Hezel, DC., Russell, S.S., Ross, A.J., Kearsley, A.T. (2008) Modal Abundances of CAIs: Implications for bulk chondrite element abundances and fractionations. Meteoritics & Planetary Science 43, 1879–1894. https://doi.org/10.1111/j.1945-5100.2008.tb00649.x
Show in context

This range is likely related to a combination of the variable modal abundances of refractory inclusions among CC (Hezel et al., 2008) that can be enriched in the lighter Ca isotopes by several per mille (Niederer and Papanastassiou, 1984; Huang et al., 2012) and the heterogeneous distribution of carbonates (Simon and DePaolo, 2010; Valdes et al., 2014; Dauphas and Pourmand, 2015).
View in article


Huang, S., Jacobsen, S.B. (2017) Calcium isotopic compositions of chondrites. Geochimica et Cosmochimica Acta 201, 364–376. https://doi.org/10.1016/j.gca.2016.09.039
Show in context

Neither the Ryugu samples nor the meteorites analysed here show any 40Ca anomalies (after age corrections), which is consistent with the literature (e.g., Simon and DePaolo, 2010; Huang and Jacobsen, 2017).
View in article
Calcium isotopic data from this study and literature (Simon and DePaolo, 2010; Valdes et al., 2014; Amsellem et al., 2017; Huang and Jacobsen, 2017).
View in article
The two heaviest Ca isotopic compositions for Orgueil samples from Valdes et al. (2014) (0.65 ± 0.17 ‰, 2 s.d.) and Huang and Jacobsen (2017) (0.75 ± 0.11 ‰, 2 s.d.) may reflect different proportions of carbonates.
View in article


Huang, S., Farkas, J., Yu, G., Petaev, M.I., Jacobsen, S.B. (2012) Calcium isotopic ratios and rare earth elements abundances from refractory inclusions from the Allende CV3 chondrite. Geochimica et Cosmochimica Acta 77, 252–265. https://doi.org/10.1016/j.gca.2011.11.002
Show in context

This range is likely related to a combination of the variable modal abundances of refractory inclusions among CC (Hezel et al., 2008) that can be enriched in the lighter Ca isotopes by several per mille (Niederer and Papanastassiou, 1984; Huang et al., 2012) and the heterogeneous distribution of carbonates (Simon and DePaolo, 2010; Valdes et al., 2014; Dauphas and Pourmand, 2015).
View in article


Kang, J.T., Ionov, D.A., Liu, F., Zhang, C.L., Golovin, A.V., Qin, L.-P., Zhang, Z.-F., Huang, F. (2017) Calcium isotopic fractionation in mantle peridotites by melting and metasomatism and Ca isotope composition of the Bulk Silicate Earth. Earth and Planetary Science Letters 474, 128–137. https://doi.org/10.1016/j.epsl.2017.05.035
Show in context

The literature data are from Table 1, BSE estimate from Kang et al. (2017) and chondrules data from Amsellem et al. (2017). Error bars are 2 x standard deviation.
View in article


King, A., Schofield, P.F., Howard, K., Russell, S.S. (2015) Modal mineralogy of CI and CI-like chondrites by X-ray diffraction. Geochimica et Cosmochimica Acta 165, 148–160. https://doi.org/10.1016/j.gca.2015.05.038
Show in context

Ca-rich phosphates exist in CI chondrites (Morlok et al., 2006), but they appear to be quite rare (0–0.05 vol. %; King et al., 2015; Alfing et al., 2019) and therefore are unlikely to have a strong control on the total Ca budget.
View in article
X-ray diffraction (detection limit ∼1 vol. %) did not reveal carbonates in three Orgueil samples (from 50 to 200 mg), but 2 vol. % in Alais (200 mg) and 3 vol. % in Ivuna (50 mg) (King et al., 2015), while Bland et al. (2004) detected no carbonates in Orgueil (200–300 mg samples).
View in article
Nakamura, T. et al. (2022) estimated the mineral abundances and compositions of the main phases of the Ryugu samples by SEM observations of two ∼10 mm2 sections from a sample from the second touchdown site (sample C0002) (see their Tables S6 and S7).
View in article


Morlok, A., Bischoff, A., Stephan, T., Floss, C., Zinner, E., Jessberger, E.K. (2006) Brecciation and chemical heterogeneities of CI chondrites. Geochimica et Cosmochimica Acta 70, 5371–5394. https://doi.org/10.1016/j.gca.2006.08.007
Show in context

Calcium sulfates are usually not detected in CIs but can be present at up to ∼1 vol. % (e.g., Endress and Bischoff, 1996; Morlok, et al., 2006).
View in article
Ca-rich phosphates exist in CI chondrites (Morlok et al., 2006), but they appear to be quite rare (0–0.05 vol. %; King et al., 2015; Alfing et al., 2019) and therefore are unlikely to have a strong control on the total Ca budget.
View in article
Thus, carbonates are the most likely major carriers of Ca in CIs (Endress and Bischoff, 1996; Morlok et al., 2006, Alfing et al., 2019).
View in article


Moynier, F., Hu, Y., Wang, K., Zhao, Y., Gérard, Y., Deng, Z., Moureau, J., Li, W., Simon, J.I., Teng, F.-Z. (2021) Potassium isotopic composition of various samples using a dual-path collision-cell-capable multiple-collector inductively coupled plasma mass spectrometer. Chemical Geology 571, 120144. https://doi.org/10.1016/j.chemgeo.2021.120144
Show in context

The effect of concentration mismatch on the Sapphire is more significant than on traditional MC-ICP-MS (Moynier et al., 2021), and all the samples were analysed with Ca concentrations within 1 % of the standard.
View in article


Nakamura, E., Kobayashi, K., Tanaka, R., Kunihiro, T., Kitagawa, H. et al. (2022) On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective. Proceedings of the Japan Academy, Series B. 6, 227–282. https://doi.org/10.2183/pjab.98.015
Show in context

In particular, their bulk Cr and Ti isotopic signatures and the chemical abundances of most elements are within the range of CI chondrites (Nakamura E. et al., 2022; Yokoyama et al., 2022).
View in article
It should be noted that another study also found several vol. % of carbonate minerals in samples from both touchdown sites, with a large variability in Ca content between ∼1 mg grains (Nakamura E. et al., 2022) and a correlation between Ca content and the dolomite abundances of the grains (Fig. S-1).
View in article
This explanation is consistent with an episode of fluid circulation and carbonate precipitation in the Ryugu samples that occurred 2.5 to 5 Myr after CAIs formation, as dated using 53Mn-53Cr chronometry in carbonate phases (Nakamura E. et al., 2022; Yokoyama et al., 2022).
View in article


Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M. et al. (2022) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science. https://doi.org/10.1126/science.abn8671
Show in context

Despite many aspects of similarities with the CIs, the Ryugu samples display an apparent excess of Ca by over 50 %, which may be related to a heterogeneous distribution of carbonates (dolomite and calcite) (Nakamura T. et al., 2022; Yokoyama et al., 2022) between Ryugu, Orgueil and other CIs.
View in article
This calculation may underestimate the Ca fraction in carbonates because the samples also contain small Ca carbonate grains (e.g., Table S7 of Nakamura T. et al., 2022), the abundances of which could not be quantified here.
View in article
C0002 is the third largest sample among all returned grains containing the major lithology (Nakamura T. et al., 2022), suggesting that the Ca budget in the Ryugu samples is dominated by carbonates.
View in article
Future work should test whether this value is representative of the whole body by analysing other Ryugu fragments containing fewer carbonate phases and less total Ca, such as the Ryugu material in section 5 from C0002 (Nakamura T. et al., 2022), which only contains ∼75 % of its Ca in carbonates.
View in article


Niederer, F.R., Papanastassiou, D.A. (1984) Ca isotopes in refractory inclusions. Geochimica et Cosmochimica Acta 48, 1279–1293. https://doi.org/10.1016/0016-7037(84)90062-0
Show in context

This range is likely related to a combination of the variable modal abundances of refractory inclusions among CC (Hezel et al., 2008) that can be enriched in the lighter Ca isotopes by several per mille (Niederer and Papanastassiou, 1984; Huang et al., 2012) and the heterogeneous distribution of carbonates (Simon and DePaolo, 2010; Valdes et al., 2014; Dauphas and Pourmand, 2015).
View in article


Palme, H., Lodders, K., Jones, A. (2014) 2.2 - Solar System abundances of the elements. In: Holland, H.D., Turekian, K.K. (Exec. Eds.) Treatise on Geochemistry (Second Edition). Elsevier, Oxford, 15–36. https://doi.org/10.1016/B978-0-08-095975-7.00118-2
Show in context

Among meteorites, CI chondrites have chemical compositions that most closely resemble the Sun; therefore, they are the most representative samples of the solar nebula composition with the exception of volatile elements (Palme et al., 2014).
View in article


Russell, W.A., Papanastassiou, D.A., Tombrello, T.A. (1978) Ca isotope fractionation on the Earth and other solar system materials. Geochimica et Cosmochimica Acta 42, 1075–1090. https://doi.org/10.1016/0016-7037(78)90105-9
Show in context

The radiogenic ingrowth on 40Ca is reported using the epsilon notation, with (40Ca/44Ca)n representing the 40Ca/44Ca ratio corrected from the mass dependent isotopic fractionation after being normalised to the 42Ca/44Ca ratio using the exponential law and 42Ca/44Ca = 0.31221 (Russell et al., 1978).
View in article


Saiki, S., Imamura, H., Arakawa, M., Wada, K., Takagi, Y., Hayakawa, M., Shirai, K., Yano, H., Okamoto, C. (2017) The Small Carry-on Impactor (SCI) and the Hayabusa2 Impact Experiment. Space Science Reviews 208, 165–186. https://doi.org/10.1007/s11214-016-0297-5
Show in context

Approximately 2 g of samples likely representing a mixture of materials from the surface and subsurface were collected into Chamber C at a site that was close to the crater formed by the Small Carry-on Impactor, a kinetic impact experiment of the Hayabusa2 mission (Saiki et al., 2017; Arakawa et al., 2020).
View in article


Simon, J.I., DePaolo, D.J. (2010) Stable calcium isotopic composition of meteorites and rocky planets. Earth and Planetary Science Letters 289, 457–466. https://doi.org/10.1016/j.epsl.2009.11.035
Show in context

This range is likely related to a combination of the variable modal abundances of refractory inclusions among CC (Hezel et al., 2008) that can be enriched in the lighter Ca isotopes by several per mille (Niederer and Papanastassiou, 1984; Huang et al., 2012) and the heterogeneous distribution of carbonates (Simon and DePaolo, 2010; Valdes et al., 2014; Dauphas and Pourmand, 2015).
View in article
Neither the Ryugu samples nor the meteorites analysed here show any 40Ca anomalies (after age corrections), which is consistent with the literature (e.g., Simon and DePaolo, 2010; Huang and Jacobsen, 2017).
View in article
Calcium isotopic data from this study and literature (Simon and DePaolo, 2010; Valdes et al., 2014; Amsellem et al., 2017; Huang and Jacobsen, 2017).
View in article


Simon, J.I., Jordan, M.J., Tappa, A., Schauble, E., Kohll, E., Young, E.D. (2017) Calcium and titanium isotope fractionation in refractory inclusions: Tracers of condensation and inheritance in the early solar system. Earth and Planetary Science Letters 472, 277–288. https://doi.org/10.1016/j.epsl.2017.05.002

Tachibana, S., Sawada, H., Okazaki, R., Takano, Y., Sakamoto, K. et al. (2022) Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth. Science 375, 1011–1016. https://doi.org/10.1126/science.abj8624
Show in context

In December 2020, the JAXA Hayabusa2 spacecraft returned to Earth with the first samples collected from a Cb-type asteroid, (162173) Ryugu (Tachibana et al., 2022; Yada et al., 2022).
View in article
The samples returned by the Hayabusa2 spacecraft consist of ∼5 g of materials from the Ryugu asteroid recovered during two touchdowns (Tachibana et al., 2022; Yada et al., 2022).
View in article


Valdes, M., Moreira, M., Foriel, J., Moynier, F. (2014) The nature of Earth’s building blocks as revealed by calcium isotopes. Earth and Planetary Science Letters 394, 135–145. https://doi.org/10.1016/j.epsl.2014.02.052
Show in context

This range is likely related to a combination of the variable modal abundances of refractory inclusions among CC (Hezel et al., 2008) that can be enriched in the lighter Ca isotopes by several per mille (Niederer and Papanastassiou, 1984; Huang et al., 2012) and the heterogeneous distribution of carbonates (Simon and DePaolo, 2010; Valdes et al., 2014; Dauphas and Pourmand, 2015).
View in article
Calcium isotopic data from this study and literature (Simon and DePaolo, 2010; Valdes et al., 2014; Amsellem et al., 2017; Huang and Jacobsen, 2017).
View in article
The two heaviest Ca isotopic compositions for Orgueil samples from Valdes et al. (2014) (0.65 ± 0.17 ‰, 2 s.d.) and Huang and Jacobsen (2017) (0.75 ± 0.11 ‰, 2 s.d.) may reflect different proportions of carbonates.
View in article


Yada, T., Abe, M., Okada, T., Nakato, A., Yogata, K. et al. (2022) Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu. Nature Astronomy 6, 214–220. https://doi.org/10.1038/s41550-021-01550-6
Show in context

In December 2020, the JAXA Hayabusa2 spacecraft returned to Earth with the first samples collected from a Cb-type asteroid, (162173) Ryugu (Tachibana et al., 2022; Yada et al., 2022).
View in article
The samples returned by the Hayabusa2 spacecraft consist of ∼5 g of materials from the Ryugu asteroid recovered during two touchdowns (Tachibana et al., 2022; Yada et al., 2022).
View in article


Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850
Show in context

In particular, their bulk Cr and Ti isotopic signatures and the chemical abundances of most elements are within the range of CI chondrites (Nakamura E. et al., 2022; Yokoyama et al., 2022).
View in article
Given that the Ryugu samples did not experience any terrestrial alteration, they are likely the chemically most pristine Solar System samples available estimating the original isotopic compositions of most elements in the Solar System (Yokoyama et al., 2022).
View in article
Despite many aspects of similarities with the CIs, the Ryugu samples display an apparent excess of Ca by over 50 %, which may be related to a heterogeneous distribution of carbonates (dolomite and calcite) (Nakamura T. et al., 2022; Yokoyama et al., 2022) between Ryugu, Orgueil and other CIs.
View in article

All samples were dissolved in PFA vials with a mixture of concentrated HF and HNO3 at the Tokyo Institute of Technology (Yokoyama et al., 2022).
View in article
The radiogenic ingrowth on 40Ca from 40K decay was corrected using the K and Ca abundances of the samples (from Yokoyama et al., 2022) and δ44/40Ca (age corrected) ratios are also presented in Table 1.
View in article
If the excess Ca in A0106-A0107 is mainly stored in secondary carbonates (Yokoyama et al., 2022 and our discussion below), then these carbonates must contribute significantly to the bulk Ca isotopic composition.
View in article
The Ca/Al ratios of bulk Chamber A and Chamber C samples from Yokoyama et al. (2022) are used for Ryugu samples in this work and are taken from the average value in Barrat et al. (2012) for Orgueil, as it was not available for specific samples used here.
View in article
This explanation is consistent with an episode of fluid circulation and carbonate precipitation in the Ryugu samples that occurred 2.5 to 5 Myr after CAIs formation, as dated using 53Mn-53Cr chronometry in carbonate phases (Nakamura E. et al., 2022; Yokoyama et al., 2022).
View in article



top

Supplementary Information

Abstract | Introduction | Samples and Methods | Results and Discussion | Acknowledgements | References | Supplementary Information


The Supplementary Information includes:
  • Supplementary Methods
  • Figures S-1 and S-2
  • Supplementary Information References


  • Download the Supplementary Information (PDF)
    top

    Figures



    Figure 1 The δ44/42Ca values plotted against δ44/40Ca values for the various samples analysed in this study, including the Ryugu samples. All the samples fall on a mass dependent line within error. Error bars represent 2 sigma standard deviation.
    Back to article


    Figure 2 A comparison of age corrected δ44/40Ca values for the samples analysed here (in colour, see Fig. 1) and from the literature (grey). Ryugu samples from Chambers A and C are similar within error and fall within the range defined by the CI chondrites. The literature data are from Table 1, BSE estimate from Kang et al. (2017)

    Kang, J.T., Ionov, D.A., Liu, F., Zhang, C.L., Golovin, A.V., Qin, L.-P., Zhang, Z.-F., Huang, F. (2017) Calcium isotopic fractionation in mantle peridotites by melting and metasomatism and Ca isotope composition of the Bulk Silicate Earth. Earth and Planetary Science Letters 474, 128–137. https://doi.org/10.1016/j.epsl.2017.05.035

    and chondrules data from Amsellem et al. (2017)

    Amsellem, E., Moynier, F., Pringle, E., Bouvier, A., Chen, H., Day, J.M.D. (2017) Testing the chondrule-rich accretion model for planetary embryos using calcium isotopes. Earth and Planetary Science Letters 469, 75–83. https://doi.org/10.1016/j.epsl.2017.04.022

    . Error bars are 2 x standard deviation.
    Back to article


    Figure 3 δ44/40Ca plotted against the Ca/Al ratio of the samples. The Ca/Al ratios of bulk Chamber A and Chamber C samples from Yokoyama et al.

    Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

    (2022

    Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2022) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science https://doi.org/10.1126/science.abn7850

    ) are used for Ryugu samples in this work and are taken from the average value in Barrat et al.

    Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C. et al. (2012) Geochemistry of CI chondrites: Major and trace elements, and Cu and Zn Isotopes. Geochimica et Cosmochimica Acta 83, 79–92. https://doi.org/10.1016/j.gca.2011.12.011

    (2012

    Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C. et al. (2012) Geochemistry of CI chondrites: Major and trace elements, and Cu and Zn Isotopes. Geochimica et Cosmochimica Acta 83, 79–92. https://doi.org/10.1016/j.gca.2011.12.011

    ) for Orgueil, as it was not available for specific samples used here.
    Back to article

    • Contact us
    • |
    • Subscribe
    Sign up for our newsletter
    • Connect with us
    • facebook
    • twitter
    • youtube

    Geochemical Perspectives Letters is a registered trademark of the European Association of Geochemistry
    ISSN 2410-339X (print) | ISSN 2410-3403 (online)
    EAG Privacy Policy