Ge, Te, and Zn isotopic link between Ryugu and CI chondrites

E. Wölfer, J. Hellmann, C. Burkhardt, T. Kleine; E. Wu00f6lfer; J. Hellmann; C. Burkhardt; T. Kleine

by admin | Sep 17, 2025 | mainpost, vol37

TY  - JOUR
T1  - Ge, Te, and Zn isotopic link between Ryugu and CI chondrites
JO  - Geochemical Perspectives Letters
VL  - 37
SP  - 1
EP  - 6
PY  - 2025
AU  - E. WölferAU  - J. HellmannAU  - C. BurkhardtAU  - T. KleineDO  - https://doi.org/10.7185/geochemlet.2537
UR  - https://www.geochemicalperspectivesletters.org/article2537
AB  - Analyses of samples returned from asteroid Ryugu have revealed chemical, mineralogical, and isotopic similarities to Ivuna-type (CI) carbonaceous chondrites. Compared to other carbonaceous chondrites, CI chondrites are characterised by heavy isotope enrichments of the moderately volatile elements, but until now no study demonstrated that this is also the case for Ryugu. Here we show that Ryugu and CI chondrites have similar elemental and mass dependent isotope systematics of the moderately volatile elements Ge, Te, and Zn, which are distinct from those of all other carbonaceous chondrites. The mass independent (nucleosynthetic) Zn isotope signatures of Ryugu are also most similar to CI chondrites, although the difference to other carbonaceous chondrites is not well resolved. Our results reinforce the notion that Ryugu and CI chondrites formed from the same precursor materials, and indicate that any processes acting on these materials before or after parent body accretion were similar. Given their similar chemical composition to the Sun, Ryugu/CI chondrites likely record the solar system’s average chemical and mass dependent isotopic composition for moderately volatile elements.

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Ge, Te, and Zn isotopic link between Ryugu and CI chondrites

E. Wölfer¹,

¹Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany

J.L. Hellmann¹,

¹Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany

C. Burkhardt¹,

¹Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany

T. Kleine¹

¹Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany

Affiliations | Corresponding Author | Cite as | Funding information

Geochemical Perspectives Letters v37 | https://doi.org/10.7185/geochemlet.2537
Received 12 May 2025 | Accepted 15 August 2025 | Published 17 September 2025

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

Keywords: Ryugu, CI chondrites, moderately volatile elements, germanium, tellurium, zinc



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Abstract

Analyses of samples returned from asteroid Ryugu have revealed chemical, mineralogical, and isotopic similarities to Ivuna-type (CI) carbonaceous chondrites. Compared to other carbonaceous chondrites, CI chondrites are characterised by heavy isotope enrichments of the moderately volatile elements, but until now no study demonstrated that this is also the case for Ryugu. Here we show that Ryugu and CI chondrites have similar elemental and mass dependent isotope systematics of the moderately volatile elements Ge, Te, and Zn, which are distinct from those of all other carbonaceous chondrites. The mass independent (nucleosynthetic) Zn isotope signatures of Ryugu are also most similar to CI chondrites, although the difference to other carbonaceous chondrites is not well resolved. Our results reinforce the notion that Ryugu and CI chondrites formed from the same precursor materials, and indicate that any processes acting on these materials before or after parent body accretion were similar. Given their similar chemical composition to the Sun, Ryugu/CI chondrites likely record the solar system’s average chemical and mass dependent isotopic composition for moderately volatile elements.

Figures and Tables

Figure 1 Diagrams of (a) Ge concentration vs. δ^74/70Ge, (b) Te concentration vs. δ^128/126Te, (c) Te vs. Ge concentrations, and (d) δ^128/126Te vs. δ^74/70Ge for carbonaceous chondrites (data from this study in dark blue; literature data in light blue [small symbols represent individual samples; large symbols represent group averages]). Ryugu sample A0220 is plotted as orange circle. Literature data for Ge is from Wölfer et al. (2025a); data for Te is from Hellmann et al. (2020, 2023) and Morton et al. (2024). The data of Morton et al. (2024) are re-normalised to δ^128/126Te and the SRM standard used by Hellmann et al. (2020, 2023). Linear regressions calculated using IsoplotR based on group averages.	Figure 2 (a) μ⁶⁶Zn vs. μ⁶⁸Zn and (b) μ⁶⁶Zn vs. μ⁶⁷Zn diagrams for carbonaceous chondrites. Symbols as in Figure 1. Ryugu sample A0220 plots within the CC field and, together with CI chondrites, is characterised by slightly smaller μⁱZn values compared to Tarda and Tagish Lake. Literature data from Steller et al. (2022).	Table 1 Germanium, Te, and Zn concentration and isotopic data for Ryugu (A0220) and carbonaceous chondrites.
Figure 1	Figure 2	Table 1

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Introduction

Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 mission returned 5.4 g of sample of the Cb-type asteroid 162173 Ryugu to Earth (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

). Initial analyses of the returned samples have revealed that Ryugu is petrologically, mineralogically, chemically, and isotopically similar to the Ivuna-type (CI) chondrites (Nakamura et al., 2023

Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M.E. et al. (2023) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science 379, eabn8671. https://doi.org/10.1126/science.abn8671

; Yokoyama et al., 2023a

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

,b

Yokoyama, T., Wadhwa, M., Iizuka, T., Rai, V., Gautam, I. et al. (2023b) Water circulation in Ryugu asteroid affected the distribution of nucleosynthetic isotope anomalies in returned sample. Science Advances 9, eadi7048. https://doi.org/10.1126/sciadv.adi7048

). These chondrites belong to the carbonaceous chondrites and with the exception of the highly volatile elements, their chemical composition closely resembles that of the solar photosphere. As such, CI chondrites are commonly taken to represent the bulk chemical composition of the solar system (e.g., Palme and O’Neill, 2014

Palme, H., O’Neill, H.St.C. (2014) 3.1 - Cosmochemical Estimates of Mantle Composition. In: Holland, H.D., Turekian, K.K. (Eds.) Treatise on Geochemistry. Second Edition, Elsevier, Amsterdam, 1–39. https://doi.org/10.1016/B978-0-08-095975-7.00201-1

). Compared to most other carbonaceous chondrites, CI chondrites are extremely rare, and owing to their friable nature, are susceptible to terrestrial alteration, which may have modified their compositions (e.g., Bland et al., 2006

Bland, P.A., Zolensky, M.E., Benedix, G.K., Sephton, M.A. (2006) Weathering of Chondritic Meteorites. In: Lauretta, D.S., McSween, H.Y. (Eds.) Meteorites and the Early Solar System II. University of Arizona Press, Tucson, 853–868. https://doi.org/10.2307/j.ctv1v7zdmm.45

; Barrat et al., 2012

Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C., Bayon, G. (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

; Koefoed et al., 2023

Koefoed, P., Barrat, J.-A., Pravdivtseva, O., Alexander, C.M.O’D., Lodders, K., Ogliore, R., Wang, K. (2023) The potassium isotopic composition of CI chondrites and the origin of isotopic variations among primitive planetary bodies. Geochimica et Cosmochimica Acta 358, 49–60. https://doi.org/10.1016/j.gca.2023.07.025

). Thus, the returned samples from asteroid Ryugu provide the unique opportunity to examine CI chondrite-like material unaffected by terrestrial alteration.

Among the carbonaceous chondrites, CI chondrites exhibit unique nucleosynthetic isotope signatures for Fe and Ni (Hopp et al., 2022

Hopp, T., Dauphas, N., Abe, Y., Aléon, J., Alexander, C.M.O’D. et al. (2022) Ryugu’s nucleosynthetic heritage from the outskirts of the Solar System. Science Advances 8, eadd8141. https://doi.org/10.1126/sciadv.add8141

; Spitzer et al., 2024

Spitzer, F., Kleine, T., Burkhardt, C., Hopp, T., Yokoyama, T. et al. (2024) The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites. Science Advances 10, eadp2426. https://doi.org/10.1126/sciadv.adp2426

) and also show distinct mass dependent isotope compositions for the moderately volatile elements (MVEs; those that condense from a solar gas between ∼1250 and 650 K). However, while Ryugu and Orgueil, the most commonly analysed CI chondrite, have indistinguishable mass dependent isotopic composition of the MVEs Zn (Paquet et al., 2023

Paquet, M., Moynier, F., Yokoyama, T., Dai, W., Hu, Y. et al. (2023) Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis. Nature Astronomy 7, 182–189. https://doi.org/10.1038/s41550-022-01846-1

) and K (Hu et al., 2024

Hu, Y., Moynier, F., Dai, W., Paquet, M., Yokoyama, T. et al. (2024) Pervasive aqueous alteration in the early Solar System revealed by potassium isotopic variations in Ryugu samples and carbonaceous chondrites. Icarus 409, 115884. https://doi.org/10.1016/j.icarus.2023.115884

), these compositions also overlap with those of other volatile-rich carbonaceous chondrites and, therefore, do not provide a clear link between CI chondrites and Ryugu. Moreover, while Ryugu samples exhibit nucleosynthetic Zn isotope anomalies similar to CI chondrites, these compositions overlap with those of other carbonaceous chondrites (Paquet et al., 2023

Paquet, M., Moynier, F., Yokoyama, T., Dai, W., Hu, Y. et al. (2023) Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis. Nature Astronomy 7, 182–189. https://doi.org/10.1038/s41550-022-01846-1

). Given these ambiguities, it is important to assess whether there are other MVEs having isotopic signatures that would provide a link between CI chondrites and Ryugu, and allow distinguishing these materials from other carbonaceous chondrites. This is important for fully understanding the chemical and isotopic make-up of asteroid Ryugu, the nature of the processes determining compositional variations among CI chondrite-like materials, and, ultimately, the use of these materials to determine the bulk chemical composition of the solar system.

The two MVEs Ge and Te hold considerable promise to reveal compositional signatures that link Ryugu to CI chondrites and distinguish them from other carbonaceous chondrites. Both elements have been shown to display large and systematic mass dependent isotopic variations among the carbonaceous chondrites, where CI chondrites are characterised by the highest Ge and Te concentrations and strongest heavy isotope enrichments (Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

; Wölfer et al., 2025a

Wölfer, E., Burkhardt, C., Nimmo, F., Kleine, T. (2025a) Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites. Earth and Planetary Science Letters 663, 119435. https://doi.org/10.1016/j.epsl.2025.119435

). Given the strong genetic and chemical link between Ryugu and CI chondrites, Ryugu is expected to exhibit similarly distinct Ge and Te isotope systematics. To assess as to whether this is the case, we report Ge and Te isotope data for a single Ryugu sample together with data for several other MVE-rich carbonaceous chondrites. To facilitate direct comparison to the MVE Zn, all samples have also been analysed for their Zn isotope compositions.

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Samples and Methods

We analysed a 12.4 mg Ryugu sample from chamber A (A0220) together with equivalent masses of Orgueil and the ungrouped C2 chondrites Tarda and Tagish Lake. To test the reproducibility of the isotope measurements on such small sample masses, and to assess the magnitude of any potential heterogeneity at the ∼12 mg level, six aggregate samples of Tagish Lake, each weighing ∼12–15 mg, were also analysed. Similar to CI chondrites and Ryugu, Tagish Lake is dominated by fine grained, volatile-rich matrix with only very low abundances of chondrules, refractory inclusions, and FeNi metal (e.g., Alexander, 2019

Alexander, C.M.O’D. (2019) Quantitative models for the elemental and isotopic fractionations in chondrites: The carbonaceous chondrites. Geochimica et Cosmochimica Acta 254, 277–309. https://doi.org/10.1016/j.gca.2019.02.008

), making this sample suitable to assess the effect of any potential sample heterogeneity on the elemental and isotopic compositions of MVEs in matrix-rich carbonaceous chondrites. The Orgueil sample analysed in this study is an aliquot from a ∼0.7 g powder prepared in a prior study (Schneider et al., 2023

Schneider, J.M., Burkhardt, C., Kleine, T. (2023) Distribution of s-, r-, and p-process Nuclides in the Early Solar System Inferred from Sr Isotope Anomalies in Meteorites. The Astrophysical Journal Letters 952, L25. https://doi.org/10.3847/2041-8213/ace187

). Finally, for direct comparison we also analysed aliquots of the large, homogenised MS-A powder of the CV3 chondrite Allende, which has previously been analysed for Ge and Te isotopes using the same analytical setup as in this study (Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

; Wölfer et al., 2025a

Wölfer, E., Burkhardt, C., Nimmo, F., Kleine, T. (2025a) Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites. Earth and Planetary Science Letters 663, 119435. https://doi.org/10.1016/j.epsl.2025.119435

).

The sample digestion, chemical separation and isotope measurements of Ge, Te, and Zn followed our previously established procedures (Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

; Steller et al., 2022

Steller, T., Burkhardt, C., Yang, C., Kleine, T. (2022) Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles. Icarus 386, 115171. https://doi.org/10.1016/j.icarus.2022.115171

; Wölfer et al., 2025a

Wölfer, E., Burkhardt, C., Nimmo, F., Kleine, T. (2025a) Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites. Earth and Planetary Science Letters 663, 119435. https://doi.org/10.1016/j.epsl.2025.119435

,b

Wölfer, E., Burkhardt, C., Kleine, T. (2025b) Germanium stable isotope measurements by double-spike MC-ICPMS. Journal of Analytical Atomic Spectrometry 40, 1023–1036. https://doi.org/10.1039/D4JA00359D

) and are described in the Supplementary Information. For Ge and Te, the instrumental mass bias was corrected using ⁷⁰Ge–⁷³Ge (Wölfer et al., 2025b

Wölfer, E., Burkhardt, C., Kleine, T. (2025b) Germanium stable isotope measurements by double-spike MC-ICPMS. Journal of Analytical Atomic Spectrometry 40, 1023–1036. https://doi.org/10.1039/D4JA00359D

) and ¹²³Te–¹²⁵Te double spikes (Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

), and the data are reported as the per mille deviations from certified standard solutions (see Table 1 for definitions). The double spike measurements also provide precise Ge and Te concentrations determined by isotope dilution. No double spike was used for Zn, and the instrumental mass bias was corrected by standard sample bracketing. This has the advantage that for Zn we can also report mass independent isotope variations (i.e. nucleosynthetic isotope anomalies) after internal normalisation of the data. As for Ge and Te, the mass dependent Zn isotope data are reported as the per mille deviations from a certified standard solution, while the nucleosynthetic isotope anomalies are given as the ppm deviations from the standard after internal normalisation to either ⁶⁸Zn/⁶⁴Zn or ⁶⁷Zn/⁶⁴Zn.

Table 1 Germanium, Te, and Zn concentration and isotopic data for Ryugu (A0220) and carbonaceous chondrites.

Sample

Weight
(mg)

Ge (μg/g)
(±2σ)

n
(Ge)

δ^74/70Ge
(±95 % CI)

Te (ng/g)
(±2σ)

n
(Te)

δ^128/126Te
(±2 s.d.)

Zn (μg/g)

n
(Zn)

δ^66/64Zn
(±2 s.d.)

μ⁶⁶Zn
(±95 % CI)

μ⁶⁸Zn
(±95 % CI)

μ⁶⁶Zn
(±95 % CI)

μ⁶⁸Zn
(±95 % CI)

⁶⁷Zn/⁶⁴Zn int. norm.

⁶⁸Zn/⁶⁴Zn int. norm.

Ryugu (A0220)

12.4

37.2 ± 0.2

12

0.93 ± 0.03

2372 ± 8

3

0.13 ± 0.03

348

14

0.51 ± 0.12

36 ± 2

16 ± 4

27 ± 1

–12 ± 3

Orgueil (CI)

12.7

33.9 ± 0.2

12

1.01 ± 0.03

2269 ± 7

3

0.15 ± 0.02

318

10

0.51 ± 0.08

36 ± 2

16 ± 6

28 ± 2

–12 ± 4

Orgueil (CI)^a

7.9

298

16

0.53 ± 0.11

36 ± 5

14 ± 9

28 ± 3

–10 ± 7

Tagish Lake (C2 ung.)

11.5

25.6 ± 0.3

9

0.67 ± 0.03

1729 ± 6

3

0.13 ± 0.03

196

8

0.51 ± 0.08

43 ± 3

21 ± 5

33 ± 2

–16 ± 3

Tagish Lake (C2 ung.)

11.6

25.2 ± 0.3

9

0.65 ± 0.03

1764 ± 6

3

0.12 ± 0.03

202

8

0.63 ± 0.05

42 ± 3

18 ± 4

33 ± 1

–13 ± 3

Tagish Lake (C2 ung.)

12.5

25.1 ± 0.3

9

0.66 ± 0.04

1556 ± 5

4

0.12 ± 0.06

188

8

0.52 ± 0.04

43 ± 3

19 ± 6

34 ± 3

–14 ± 5

Tagish Lake (C2 ung.)

11.7

25.5 ± 0.3

9

0.67 ± 0.02

1647 ± 5

3

0.10 ± 0.01

187

8

0.57 ± 0.06

44 ± 5

20 ± 9

34 ± 2

–15 ± 7

Tagish Lake (C2 ung.)

14.8

26.2 ± 0.3

9

0.71 ± 0.03

1756 ± 6

4

0.12 ± 0.05

197

8

0.53 ± 0.09

45 ± 3

20 ± 4

35 ± 3

–15 ± 3

Tagish Lake (C2 ung.)

13.3

25.5 ± 0.3

9

0.72 ± 0.02

1691 ± 6

4

0.11 ± 0.03

188

6

0.48 ± 0.03

42 ± 1

17 ± 6

33 ± 2

–13 ± 5

Mean (2 s.d., n = 6)

25.5 ± 0.8

0.68 ± 0.06

1690 ± 157

0.12 ± 0.02

193

0.54 ± 0.10

43 ± 2

19 ± 3

33 ± 2

–14 ± 3

Wt. mean (IsoplotR)

25.4 ± 0.1

0.69 ± 0.02

1679 ± 67

0.11 ± 0.01

193

0.53 ± 0.02

42 ± 1

19 ± 2

33 ± 1

–15 ± 2

Tarda (C2 ung.)

16.3

24.4 ± 0.2

4

0.73 ± 0.03

1622 ± 5

3

0.07 ± 0.07

194

9

0.54 ± 0.05

48 ± 3

25 ± 5

35 ± 2

–19 ± 4

Tarda (C2 ung.) ^a

13.0

205

15

0.46 ± 0.06

43 ± 6

21 ± 7

31 ± 6

–16 ± 6

J. Winselwan (CM) ^a

17.9

183

20

0.41 ± 0.08

41 ± 5

19 ± 11

31 ± 2

–14 ± 8

Allende (CV)

102.9

17.2 ± 0.2

6

0.02 ± 0.03

954 ± 3

4

0.02 ± 0.02

111

25

0.31 ± 0.07

38 ± 2

15 ± 2

31 ± 1

–11 ± 2

Allende (CV) ^a

74.3

108

68

0.27 ± 0.08

43 ± 3

19 ± 6

32 ± 1

–15 ± 4

Vigarano (CV) ^a

30.2

104

15

0.17 ± 0.05

43 ± 4

15 ± 8

35 ± 2

–11 ± 6

Kainsaz (CO) ^a

28.7

94

18

0.38 ± 0.05

38 ± 4

17 ± 7

30 ± 3

–12 ± 5

The Ge and Te concentrations were determined by isotope dilution and the Zn concentrations were determined by quadrupole ICP–MS, the latter of which have an uncertainty of ∼5 %. The isotope data of individual samples are reported as the mean of pooled measurements and are expressed as in the common δ notation as δ⁷⁴Ge [‰] = [(⁷⁴Ge/⁷⁰Ge)_sample/(⁷⁴Ge/⁷⁰Ge)_SRM3210a – 1] × 10³, δ¹²⁸Te [‰] = [(¹²⁸Te/¹²⁶Te)_sample/(¹²⁸Te/¹²⁶Te)_SRM3156 – 1] × 10³, δ⁶⁶Zn [‰] = [(⁶⁶Zn/⁶⁴Zn)_sample/(⁶⁶Zn/⁶⁴Zn)_JMC,Lyon – 1] × 10³, and μⁱZn = [(ⁱZn/⁶⁴Zn)_sample/(ⁱZn/⁶⁴Zn)_SRM683 − 1] × 10⁶, respectively. n: number of isotope analyses.
^aMass independent Zn isotope data previously published in Steller et al. (2022)Steller, T., Burkhardt, C., Yang, C., Kleine, T. (2022) Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles. Icarus 386, 115171. https://doi.org/10.1016/j.icarus.2022.115171.

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Results

The Ge, Te, and Zn concentrations and isotopic compositions of Ryugu (A0220) and the carbonaceous chondrites investigated in this study are provided in Table 1. We show in the SI (Tables S-1 to S-3, Fig. S-1) that the new data for Orgueil, Tagish Lake, Tarda, and Allende agree well with results of prior studies, demonstrating that the combined use of two different double spikes has no effect on the isotope analyses of any of the three elements investigated, and that analysing mg-sized samples does not compromise the accuracy and precision of the isotopic data. While the six Tagish Lake subsamples have similar Ge, Te, and Zn concentrations and isotopic compositions, they show resolved δ^74/70Ge and δ^66/64Zn variations, indicating some level of compositional heterogeneities at the ∼12 mg sampling scale (Fig. S-2). This heterogeneity appears to be more pronounced for Zn, where our analyses of several samples of Tagish Lake are systematically offset from some prior analyses (Fig. S-2).

Ryugu sample A0220 and Orgueil have the highest Ge, Te, and Zn concentrations and are characterised by the most elevated δ^74/70Ge and δ^128/126Te values among the carbonaceous chondrites of this and prior studies (Figs. 1, S-3). Consistent with Paquet et al. (2023)

Paquet, M., Moynier, F., Yokoyama, T., Dai, W., Hu, Y. et al. (2023) Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis. Nature Astronomy 7, 182–189. https://doi.org/10.1038/s41550-022-01846-1

, we find no δ^66/64Zn differences among Ryugu sample A0220, Orgueil, Tagish Lake, and Tarda, despite their different Zn contents. Compared to CI chondrites, Ryugu sample A0220 is enriched in Ge, Te, and Zn by ∼5–10 %, consistent with the ∼10 % higher Zn concentrations found in prior studies (Paquet et al., 2023

Paquet, M., Moynier, F., Yokoyama, T., Dai, W., Hu, Y. et al. (2023) Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis. Nature Astronomy 7, 182–189. https://doi.org/10.1038/s41550-022-01846-1

; Yokoyama et al., 2023a

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

). These higher MVE concentrations can partly or wholly be accounted for by the >6 wt. % lower water content of Ryugu samples compared to CI chondrites, and ultimately might stem from the incorporation of terrestrial water into CI meteorites and/or the loss of water from Ryugu’s surface during space weathering (Noguchi et al., 2023

Noguchi, T., Matsumoto, T., Miyake, A., Igami, Y., Haruta, M. et al. (2023) A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu. Nature Astronomy 7, 170–181. https://doi.org/10.1038/s41550-022-01841-6

; Yokoyama et al., 2023a

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

). For Ge, the δ^74/70Ge of sample A0220 is ∼0.07 ‰ lower than for Orgueil samples analysed in this and previous studies. This difference is similar to those found among the subsamples of Tagish Lake, indicating these differences most likely reflect sample heterogeneity. This is likely also the case for Te, where sample A0220 has the same δ^128/126Te as Ivuna (Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

), but a slightly lower δ^128/126Te than two analyses of Orgueil (from this study and Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

).

**Figure 1** Diagrams of **(a)** Ge concentration *vs.* δ^74/70Ge, **(b)** Te concentration *vs.* δ^128/126Te, **(c)** Te vs. Ge concentrations, and **(d)** δ^128/126Te *vs.* δ^74/70Ge for carbonaceous chondrites (data from this study in dark blue; literature data in light blue [small symbols represent individual samples; large symbols represent group averages]). Ryugu sample A0220 is plotted as orange circle. Literature data for Ge is from Wölfer *et al.* (2025a)
Wölfer, E., Burkhardt, C., Nimmo, F., Kleine, T. (2025a) Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites. *Earth and Planetary Science Letters* 663, 119435. https://doi.org/10.1016/j.epsl.2025.119435
; data for Te is from Hellmann *et al.* (2020
Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. *Earth and Planetary Science Letters* 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508
, 2023
Hellmann, J.L., Schneider, J.M., Wölfer, E., Dra˛z˙kowska, J., Jansen, C.A., Hopp, T., Burkhardt, C., Kleine, T. (2023) Origin of Isotopic Diversity among Carbonaceous Chondrites. *The Astrophysical Journal Letters* 946, L34. https://doi.org/10.3847/2041-8213/acc102
) and Morton *et al.* (2024)
Morton, E.M., Pickard, H., Wombacher, F., Huang, Y., Palk, E., Martins, R., Kuthning, S., Schönbächler, M., Rehkämper, M. (2024) Volatile Element Depletion of Carbonaceous Chondrites—Insights from Mass-dependent Zinc, Cadmium, and Tellurium Isotope Variations. *The Astrophysical Journal* 977, 53. https://doi.org/10.3847/1538-4357/ad87ed
. The data of Morton *et al.* (2024)
Morton, E.M., Pickard, H., Wombacher, F., Huang, Y., Palk, E., Martins, R., Kuthning, S., Schönbächler, M., Rehkämper, M. (2024) Volatile Element Depletion of Carbonaceous Chondrites—Insights from Mass-dependent Zinc, Cadmium, and Tellurium Isotope Variations. *The Astrophysical Journal* 977, 53. https://doi.org/10.3847/1538-4357/ad87ed
are re-normalised to δ^128/126Te and the SRM standard used by Hellmann *et al.* (2020
Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. *Earth and Planetary Science Letters* 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508
, 2023
Hellmann, J.L., Schneider, J.M., Wölfer, E., Dra˛z˙kowska, J., Jansen, C.A., Hopp, T., Burkhardt, C., Kleine, T. (2023) Origin of Isotopic Diversity among Carbonaceous Chondrites. *The Astrophysical Journal Letters* 946, L34. https://doi.org/10.3847/2041-8213/acc102
). Linear regressions calculated using IsoplotR based on group averages.

For the nucleosynthetic Zn isotope anomalies, sample A0220, together with the other carbonaceous chondrites of this study, plots in the CC field on μ⁶⁶Zn–μ⁶⁸Zn and μ⁶⁶Zn–μ⁶⁷Zn diagrams (Fig. 2). The results for Orgueil, Tagish Lake, Tarda, and Allende agree well with those of prior studies. Ryugu sample A0220 is characterised by μ⁶⁶Zn = 36 ± 2, identical to the values measured for Orgueil in this study and by Steller et al. (2022)

Steller, T., Burkhardt, C., Yang, C., Kleine, T. (2022) Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles. Icarus 386, 115171. https://doi.org/10.1016/j.icarus.2022.115171

(the latter data have been corrected for a small –9 ppm offset measured for terrestrial samples). The only other study on Zn isotope anomalies in Ryugu only reported μ⁶⁶Zn values using the ⁶⁸Zn/⁶⁴Zn normalisation (Paquet et al., 2023

Paquet, M., Moynier, F., Yokoyama, T., Dai, W., Hu, Y. et al. (2023) Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis. Nature Astronomy 7, 182–189. https://doi.org/10.1038/s41550-022-01846-1

), which results in overall smaller anomalies than the ⁶⁷Zn/⁶⁴Zn normalisation. These authors found a mean μ⁶⁶Zn = 33 ± 4 (2 s.e.) for samples from chambers A and C, slightly higher than μ⁶⁶Zn = 27 ± 1 (95 % conf.) (⁶⁸Zn/⁶⁴Zn normalisation) measured here.

**Figure 2** **(a)** μ⁶⁶Zn *vs.* μ⁶⁸Zn and **(b)** μ⁶⁶Zn *vs.* μ⁶⁷Zn diagrams for carbonaceous chondrites. Symbols as in Figure 1. Ryugu sample A0220 plots within the CC field and, together with CI chondrites, is characterised by slightly smaller μⁱZn values compared to Tarda and Tagish Lake. Literature data from Steller *et al.* (2022)
Steller, T., Burkhardt, C., Yang, C., Kleine, T. (2022) Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles. *Icarus* 386, 115171. https://doi.org/10.1016/j.icarus.2022.115171
.

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Discussion

A genetic link between asteroid Ryugu and CI chondrites has been established in numerous studies, based on for instance nucleosynthetic isotope anomalies in the non-volatile elements Cr, Ti, Fe, and Ni (Hopp et al., 2022

Hopp, T., Dauphas, N., Abe, Y., Aléon, J., Alexander, C.M.O’D. et al. (2022) Ryugu’s nucleosynthetic heritage from the outskirts of the Solar System. Science Advances 8, eadd8141. https://doi.org/10.1126/sciadv.add8141

; Yokoyama et al., 2023a

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

, 2023b

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

; Spitzer et al., 2024

Spitzer, F., Kleine, T., Burkhardt, C., Hopp, T., Yokoyama, T. et al. (2024) The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites. Science Advances 10, eadp2426. https://doi.org/10.1126/sciadv.adp2426

). Among the MVEs, Zn also shows nucleosynthetic isotope anomalies, but until now no isotopic variations among the carbonaceous chondrites have been identified (Savage et al., 2022

Savage, P.S., Moynier, F., Boyet, M. (2022) Zinc isotope anomalies in primitive meteorites identify the outer solar system as an important source of Earth’s volatile inventory. Icarus 386, 115172. https://doi.org/10.1016/j.icarus.2022.115172

; Steller et al., 2022

Steller, T., Burkhardt, C., Yang, C., Kleine, T. (2022) Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles. Icarus 386, 115171. https://doi.org/10.1016/j.icarus.2022.115171

; Martins et al., 2023

Martins, R., Kuthning, S., Coles, B.J., Kreissig, K., Rehkämper, M. (2023) Nucleosynthetic isotope anomalies of zinc in meteorites constrain the origin of Earth’s volatiles. Science 379, 369–372. https://doi.org/10.1126/science.abn1021

). However, the data of this study suggest that CI chondrites and Ryugu may have distinct nucleosynthetic Zn isotope signatures compared to other carbonaceous chondrites. We find identical μ⁶⁶Zn values for two separate analyses of Orgueil (μ⁶⁶Zn = 36 ± 5 in Steller et al., 2022

Steller, T., Burkhardt, C., Yang, C., Kleine, T. (2022) Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles. Icarus 386, 115171. https://doi.org/10.1016/j.icarus.2022.115171

, and 36 ± 2 in this study) and Ryugu sample A0220 (μ⁶⁶Zn = 36 ± 2). By contrast, for the next most volatile-rich carbonaceous chondrites, Tagish Lake and Tarda, we find more elevated μ⁶⁶Zn values of 43 ± 2 and 48 ± 3, respectively (Table 1). This suggests that CI chondrites/Ryugu may be characterised by slightly lower μ⁶⁶Zn values than other volatile-rich carbonaceous chondrites. This difference is barely resolved, however, and there are other non-CI carbonaceous chondrites overlapping with the μ⁶⁶Zn values of CI chondrites and Ryugu (Fig. 2). As such, additional high precision Zn isotope data are needed for firmly establishing a nucleosynthetic Zn isotope difference between CI and other carbonaceous chondrites.

More robust evidence for an MVE-based link between Ryugu and CI chondrites comes from the elemental and mass dependent isotopic compositions reported here. Compositional variations among the carbonaceous chondrites are thought to reflect mixing among the chondrite’s constituent components, namely volatile-poor, isotopically light chondrules and volatile-rich, isotopically heavy, CI chondrite-like matrix (e.g., Alexander, 2019

Alexander, C.M.O’D. (2019) Quantitative models for the elemental and isotopic fractionations in chondrites: The carbonaceous chondrites. Geochimica et Cosmochimica Acta 254, 277–309. https://doi.org/10.1016/j.gca.2019.02.008

; Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

). Variations in the abundance of these two components result in correlations among the concentrations and mass dependent isotopic compositions of the MVEs, including Ge (Wölfer et al., 2025a

Wölfer, E., Burkhardt, C., Nimmo, F., Kleine, T. (2025a) Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites. Earth and Planetary Science Letters 663, 119435. https://doi.org/10.1016/j.epsl.2025.119435

), Te (Hellmann et al., 2020

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

), Zn (e.g., Pringle et al., 2017

Pringle, E.A., Moynier, F., Beck, P., Paniello, R., Hezel, D.C. (2017) The origin of volatile element depletion in early solar system material: Clues from Zn isotopes in chondrules. Earth and Planetary Science Letters 468, 62–71. https://doi.org/10.1016/j.epsl.2017.04.002

), Rb (e.g., Nie et al., 2021

Nie, N.X., Chen, X.-Y., Hopp, T., Hu, J.Y., Zhang, Z.J., Teng, F.-Z., Shahar, A., Dauphas, N. (2021) Imprint of chondrule formation on the K and Rb isotopic compositions of carbonaceous meteorites. Science Advances 7, eabl3929. https://doi.org/10.1126/sciadv.abl3929

), K (e.g., Koefoed et al., 2023

Koefoed, P., Barrat, J.-A., Pravdivtseva, O., Alexander, C.M.O’D., Lodders, K., Ogliore, R., Wang, K. (2023) The potassium isotopic composition of CI chondrites and the origin of isotopic variations among primitive planetary bodies. Geochimica et Cosmochimica Acta 358, 49–60. https://doi.org/10.1016/j.gca.2023.07.025

), and Cd (Morton et al., 2024

Morton, E.M., Pickard, H., Wombacher, F., Huang, Y., Palk, E., Martins, R., Kuthning, S., Schönbächler, M., Rehkämper, M. (2024) Volatile Element Depletion of Carbonaceous Chondrites—Insights from Mass-dependent Zinc, Cadmium, and Tellurium Isotope Variations. The Astrophysical Journal 977, 53. https://doi.org/10.3847/1538-4357/ad87ed

). Our results are consistent with these correlations and demonstrate that Ryugu and Orgueil together are characterised by distinctly higher MVE abundances and heavier isotopic compositions compared to other carbonaceous chondrites (Fig. 1). However, given the small mass analysed for each sample, it is important to assess how much of the observed variability may reflect sample heterogeneities rather than true compositional variations among the chondrite groups. For instance, different Ryugu subsamples exhibit variable Cr, Ti, and Ni nucleosynthetic isotope signatures (Yokoyama et al., 2023a

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

, 2023b

Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

; Spitzer et al., 2024

Spitzer, F., Kleine, T., Burkhardt, C., Hopp, T., Yokoyama, T. et al. (2024) The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites. Science Advances 10, eadp2426. https://doi.org/10.1126/sciadv.adp2426

), which at least in part have been attributed to the redistribution of isotopically anomalous phases during aqueous alteration in the parent body (Yokoyama et al., 2023b

Yokoyama, T., Wadhwa, M., Iizuka, T., Rai, V., Gautam, I. et al. (2023b) Water circulation in Ryugu asteroid affected the distribution of nucleosynthetic isotope anomalies in returned sample. Science Advances 9, eadi7048. https://doi.org/10.1126/sciadv.adi7048

). The pronounced Mo isotope anomalies observed for a Ryugu sample has been explained in a similar manner (Nakanishi et al., 2023

Nakanishi, N., Yokoyama, T., Ishikawa, A., Walker, R.J., Abe, Y. et al. (2023) Nucleosynthetic s-Process Depletion in Mo from Ryugu samples returned by Hayabusa2. Geochemical Perspectives Letters 28, 31–36. https://doi.org/10.7185/geochemlet.2341

). These observations suggest that small scale heterogeneities may also exist for mass dependent isotope compositions. For instance, mass dependent Zn isotope variations have been observed among the components of chondrites (Luck et al., 2005

Luck, J.-M., Othman, D.B., Albarède, F. (2005) Zn and Cu isotopic variations in chondrites and iron meteorites: Early solar nebula reservoirs and parent-body processes. Geochimica et Cosmochimica Acta 69, 5351–5363. https://doi.org/10.1016/j.gca.2005.06.018

; Pringle et al., 2017

Pringle, E.A., Moynier, F., Beck, P., Paniello, R., Hezel, D.C. (2017) The origin of volatile element depletion in early solar system material: Clues from Zn isotopes in chondrules. Earth and Planetary Science Letters 468, 62–71. https://doi.org/10.1016/j.epsl.2017.04.002

), and so over- or under-sampling of certain components having distinct isotopic compositions may have occurred.

Our results for six ∼12–15 mg subsamples of Tagish Lake show that the effects of sample heterogeneity are different for Ge, Te, and Zn. While the δ^128/126Te values are quite homogeneous, δ^74/70Ge and δ^66/64Zn values vary by ∼0.07 ‰ and ∼0.16 ‰, respectively. For Zn this difference covers almost half of the entire δ^66/64Zn variations observed among carbonaceous chondrites. By contrast, for Ge, these variations amount to only ∼3 % of the overall δ^74/70Ge variability among the carbonaceous chondrites (Wölfer et al., 2025a

Wölfer, E., Burkhardt, C., Nimmo, F., Kleine, T. (2025a) Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites. Earth and Planetary Science Letters 663, 119435. https://doi.org/10.1016/j.epsl.2025.119435

), and the difference between CI chondrites and Tagish Lake itself is about four times larger than the heterogeneity observed among the CI chondrite and Ryugu samples. These observations suggest that the disparate levels of isotopic heterogeneity among the Tagish Lake subsamples are neither controlled by volatility (because Te and Zn have similar condensation temperatures) nor by heterogeneous sampling of chondrule and matrix fractions (because in this case similar relative variations would be expected for all three elements). Instead, they more likely reflect differences in the mobility of these elements during parent body alteration, and in the magnitude of isotope fractionation among the MVE’s host minerals. Regardless of their exact cause, the larger intra-sample δ^66/64Zn variability combined with the overall smaller range of δ^66/64Zn values among carbonaceous chondrites makes Zn less suitable for linking Ryugu samples to a specific carbonaceous chondrite group than Ge and Te. Moreover, the larger overall isotope fractionation of Ge compared to Te makes mass dependent Ge isotope variations particularly powerful to identify genetic relations of MVEs among carbonaceous chondrite-like materials, especially for the small sample sizes typically available from sample return missions.

The Ge and Te results of this study demonstrate that compared to other carbonaceous chondrites, Ryugu and CI chondrites are characterised by elemental and heavy isotope enrichments in the MVEs. The same conclusion was reached previously based on Zn isotopes (Paquet et al., 2023

Paquet, M., Moynier, F., Yokoyama, T., Dai, W., Hu, Y. et al. (2023) Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis. Nature Astronomy 7, 182–189. https://doi.org/10.1038/s41550-022-01846-1

), but we emphasise that only for Ge and Te are the isotopic compositions of Ryugu and CI chondrites distinct from those of other volatile-rich carbonaceous chondrites.

Identical nucleosynthetic isotope signatures of Ryugu and CI chondrites have revealed that both formed from the same mix of presolar and nebular materials, but these signatures provide little information on any physicochemical processes acting on these materials before and after parent body accretion. The mass dependent isotopic compositions of MVEs are a more sensitive tracer of such processes, and so the MVE-based link between Ryugu and CI chondrites indicates that any physicochemical processes acting on these materials were also similar. Given the strong chemical similarities between Ryugu/CI chondrites and the solar photosphere, this in turn implies that these samples are good proxies for the average chemical and mass dependent isotopic compositions of the MVEs for most of the solar protoplanetary disk and, hence, the bulk solar system. Importantly, as is evident for instance from the distinct O isotope composition of the Sun (McKeegan et al., 2011

McKeegan, K.D., Kallio, A.P.A., Heber, V.S., Jarzebinski, G., Mao, P.H., Coath, C.D., Kunihiro, T., Wiens, R.C., Nordholt, J.E., Moses Jr., R.W., Reisenfeld, D.B., Jurewicz, A.J.G., Burnett, D.S. (2011) The Oxygen Isotopic Composition of the Sun Inferred from Captured Solar Wind. Science 332, 1528–1532. https://doi.org/10.1126/science.1204636

) for mass independent isotope anomalies, the isotopic composition of the solar system may be markedly different from that of CI chondrites, which likely was established by mixing of isotopically distinct materials during the formation and dynamical evolution of the protoplanetary disk (e.g., Nanne et al., 2019

Nanne, J.A.M., Nimmo, F., Cuzzi, J.N., Kleine, T. (2019) Origin of the non-carbonaceous–carbonaceous meteorite dichotomy. Earth and Planetary Science Letters 511, 44–54. https://doi.org/10.1016/j.epsl.2019.01.027

).

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Acknowledgements

The Ryugu samples used in this paper were distributed through The Announcement of Opportunity for Hayabusa2 samples. These samples were referred to the Ryugu Sample Database at https://www.darts.isas.jaxa.jp/curation/hayabusa2/. We gratefully acknowledge Rayssa Martins and Kun Wang for their constructive comments and Helen Williams for her editorial handling. This work was funded by the European Research Council Advanced Grant HolyEarth (grant no. 101019380).

Editor: Helen Williams

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References

Alexander, C.M.O’D. (2019) Quantitative models for the elemental and isotopic fractionations in chondrites: The carbonaceous chondrites. Geochimica et Cosmochimica Acta 254, 277–309. https://doi.org/10.1016/j.gca.2019.02.008

Show in context

Similar to CI chondrites and Ryugu, Tagish Lake is dominated by fine grained, volatile-rich matrix with only very low abundances of chondrules, refractory inclusions, and FeNi metal (e.g., Alexander, 2019), making this sample suitable to assess the effect of any potential sample heterogeneity on the elemental and isotopic compositions of MVEs in matrix-rich carbonaceous chondrites.
View in article
Compositional variations among the carbonaceous chondrites are thought to reflect mixing among the chondrite’s constituent components, namely volatile-poor, isotopically light chondrules and volatile-rich, isotopically heavy, CI chondrite-like matrix (e.g., Alexander, 2019; Hellmann et al., 2020).
View in article

Barrat, J.A., Zanda, B., Moynier, F., Bollinger, C., Liorzou, C., Bayon, G. (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

Compared to most other carbonaceous chondrites, CI chondrites are extremely rare, and owing to their friable nature, are susceptible to terrestrial alteration, which may have modified their compositions (e.g., Bland et al., 2006; Barrat et al., 2012; Koefoed et al., 2023).
View in article

Bland, P.A., Zolensky, M.E., Benedix, G.K., Sephton, M.A. (2006) Weathering of Chondritic Meteorites. In: Lauretta, D.S., McSween, H.Y. (Eds.) Meteorites and the Early Solar System II. University of Arizona Press, Tucson, 853–868. https://doi.org/10.2307/j.ctv1v7zdmm.45

Show in context

Compared to most other carbonaceous chondrites, CI chondrites are extremely rare, and owing to their friable nature, are susceptible to terrestrial alteration, which may have modified their compositions (e.g., Bland et al., 2006; Barrat et al., 2012; Koefoed et al., 2023).
View in article

Hellmann, J.L., Hopp, T., Burkhardt, C., Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508

Show in context

Both elements have been shown to display large and systematic mass dependent isotopic variations among the carbonaceous chondrites, where CI chondrites are characterised by the highest Ge and Te concentrations and strongest heavy isotope enrichments (Hellmann et al., 2020; Wölfer et al., 2025a).
View in article
Finally, for direct comparison we also analysed aliquots of the large, homogenised MS-A powder of the CV3 chondrite Allende, which has previously been analysed for Ge and Te isotopes using the same analytical setup as in this study (Hellmann et al., 2020; Wölfer et al., 2025a).
View in article
The sample digestion, chemical separation and isotope measurements of Ge, Te, and Zn followed our previously established procedures (Hellmann et al., 2020; Steller et al., 2022; Wölfer et al., 2025a,b) and are described in the Supplementary Information
View in article
For Ge and Te, the instrumental mass bias was corrected using ⁷⁰Ge–⁷³Ge (Wölfer et al., 2025b) and ¹²³Te–¹²⁵Te double spikes (Hellmann et al., 2020), and the data are reported as the per mille deviations from certified standard solutions (see Table 1 for definitions).
View in article
This is likely also the case for Te, where sample A0220 has the same δ^128/126Te as Ivuna (Hellmann et al., 2020), but a slightly lower δ^128/126Te than two analyses of Orgueil (from this study and Hellmann et al., 2020).
View in article
Literature data for Ge is from Wölfer et al. (2025a); data for Te is from Hellmann et al. (2020, 2023) and Morton et al. (2024).
View in article
The data of Morton et al. (2024) are re-normalised to δ^128/126Te and the SRM standard used by Hellmann et al. (2020, 2023).
View in article
Compositional variations among the carbonaceous chondrites are thought to reflect mixing among the chondrite’s constituent components, namely volatile-poor, isotopically light chondrules and volatile-rich, isotopically heavy, CI chondrite-like matrix (e.g., Alexander, 2019; Hellmann et al., 2020).
View in article
Variations in the abundance of these two components result in correlations among the concentrations and mass dependent isotopic compositions of the MVEs, including Ge (Wölfer et al., 2025a), Te (Hellmann et al., 2020), Zn (e.g., Pringle et al., 2017), Rb (e.g., Nie et al., 2021), K (e.g., Koefoed et al., 2023), and Cd (Morton et al., 2024).
View in article

Hellmann, J.L., Schneider, J.M., Wölfer, E., Dra˛z˙kowska, J., Jansen, C.A., Hopp, T., Burkhardt, C., Kleine, T. (2023) Origin of Isotopic Diversity among Carbonaceous Chondrites. The Astrophysical Journal Letters 946, L34. https://doi.org/10.3847/2041-8213/acc102

Show in context

Literature data for Ge is from Wölfer et al. (2025a); data for Te is from Hellmann et al. (2020, 2023) and Morton et al. (2024).
View in article
The data of Morton et al. (2024) are re-normalised to δ^128/126Te and the SRM standard used by Hellmann et al. (2020, 2023).
View in article

Hopp, T., Dauphas, N., Abe, Y., Aléon, J., Alexander, C.M.O’D. et al. (2022) Ryugu’s nucleosynthetic heritage from the outskirts of the Solar System. Science Advances 8, eadd8141. https://doi.org/10.1126/sciadv.add8141

Show in context

Among the carbonaceous chondrites, CI chondrites exhibit unique nucleosynthetic isotope signatures for Fe and Ni (Hopp et al., 2022; Spitzer et al., 2024) and also show distinct mass dependent isotope compositions for the moderately volatile elements (MVEs; those that condense from a solar gas between ∼1250 and 650 K).
View in article
A genetic link between asteroid Ryugu and CI chondrites has been established in numerous studies, based on for instance nucleosynthetic isotope anomalies in the non-volatile elements Cr, Ti, Fe, and Ni (Hopp et al., 2022; Yokoyama et al., 2023a, 2023b; Spitzer et al., 2024).
View in article

Hu, Y., Moynier, F., Dai, W., Paquet, M., Yokoyama, T. et al. (2024) Pervasive aqueous alteration in the early Solar System revealed by potassium isotopic variations in Ryugu samples and carbonaceous chondrites. Icarus 409, 115884. https://doi.org/10.1016/j.icarus.2023.115884

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However, while Ryugu and Orgueil, the most commonly analysed CI chondrite, have indistinguishable mass dependent isotopic composition of the MVEs Zn (Paquet et al., 2023) and K (Hu et al., 2024), these compositions also overlap with those of other volatile-rich carbonaceous chondrites and, therefore, do not provide a clear link between CI chondrites and Ryugu.
View in article

Koefoed, P., Barrat, J.-A., Pravdivtseva, O., Alexander, C.M.O’D., Lodders, K., Ogliore, R., Wang, K. (2023) The potassium isotopic composition of CI chondrites and the origin of isotopic variations among primitive planetary bodies. Geochimica et Cosmochimica Acta 358, 49–60. https://doi.org/10.1016/j.gca.2023.07.025

Show in context

Compared to most other carbonaceous chondrites, CI chondrites are extremely rare, and owing to their friable nature, are susceptible to terrestrial alteration, which may have modified their compositions (e.g., Bland et al., 2006; Barrat et al., 2012; Koefoed et al., 2023).
View in article
Variations in the abundance of these two components result in correlations among the concentrations and mass dependent isotopic compositions of the MVEs, including Ge (Wölfer et al., 2025a), Te (Hellmann et al., 2020), Zn (e.g., Pringle et al., 2017), Rb (e.g., Nie et al., 2021), K (e.g., Koefoed et al., 2023), and Cd (Morton et al., 2024).
View in article

Luck, J.-M., Othman, D.B., Albarède, F. (2005) Zn and Cu isotopic variations in chondrites and iron meteorites: Early solar nebula reservoirs and parent-body processes. Geochimica et Cosmochimica Acta 69, 5351–5363. https://doi.org/10.1016/j.gca.2005.06.018

Show in context

For instance, mass dependent Zn isotope variations have been observed among the components of chondrites (Luck et al., 2005; Pringle et al., 2017), and so over- or under-sampling of certain components having distinct isotopic compositions may have occurred.
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Martins, R., Kuthning, S., Coles, B.J., Kreissig, K., Rehkämper, M. (2023) Nucleosynthetic isotope anomalies of zinc in meteorites constrain the origin of Earth’s volatiles. Science 379, 369–372. https://doi.org/10.1126/science.abn1021

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Among the MVEs, Zn also shows nucleosynthetic isotope anomalies, but until now no isotopic variations among the carbonaceous chondrites have been identified (Savage et al., 2022; Steller et al., 2022; Martins et al., 2023).
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McKeegan, K.D., Kallio, A.P.A., Heber, V.S., Jarzebinski, G., Mao, P.H., Coath, C.D., Kunihiro, T., Wiens, R.C., Nordholt, J.E., Moses Jr., R.W., Reisenfeld, D.B., Jurewicz, A.J.G., Burnett, D.S. (2011) The Oxygen Isotopic Composition of the Sun Inferred from Captured Solar Wind. Science 332, 1528–1532. https://doi.org/10.1126/science.1204636

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Importantly, as is evident for instance from the distinct O isotope composition of the Sun (McKeegan et al., 2011) for mass independent isotope anomalies, the isotopic composition of the solar system may be markedly different from that of CI chondrites, which likely was established by mixing of isotopically distinct materials during the formation and dynamical evolution of the protoplanetary disk (e.g., Nanne et al., 2019).
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Morton, E.M., Pickard, H., Wombacher, F., Huang, Y., Palk, E., Martins, R., Kuthning, S., Schönbächler, M., Rehkämper, M. (2024) Volatile Element Depletion of Carbonaceous Chondrites—Insights from Mass-dependent Zinc, Cadmium, and Tellurium Isotope Variations. The Astrophysical Journal 977, 53. https://doi.org/10.3847/1538-4357/ad87ed

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Literature data for Ge is from Wölfer et al. (2025a); data for Te is from Hellmann et al. (2020, 2023) and Morton et al. (2024).
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The data of Morton et al. (2024) are re-normalised to δ^128/126Te and the SRM standard used by Hellmann et al. (2020, 2023).
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Variations in the abundance of these two components result in correlations among the concentrations and mass dependent isotopic compositions of the MVEs, including Ge (Wölfer et al., 2025a), Te (Hellmann et al., 2020), Zn (e.g., Pringle et al., 2017), Rb (e.g., Nie et al., 2021), K (e.g., Koefoed et al., 2023), and Cd (Morton et al., 2024).
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Nakamura, T., Matsumoto, M., Amano, K., Enokido, Y., Zolensky, M.E. et al. (2023) Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples. Science 379, eabn8671. https://doi.org/10.1126/science.abn8671

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Initial analyses of the returned samples have revealed that Ryugu is petrologically, mineralogically, chemically, and isotopically similar to the Ivuna-type (CI) chondrites (Nakamura et al., 2023; Yokoyama et al., 2023a,b).
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Nakanishi, N., Yokoyama, T., Ishikawa, A., Walker, R.J., Abe, Y. et al. (2023) Nucleosynthetic s-Process Depletion in Mo from Ryugu samples returned by Hayabusa2. Geochemical Perspectives Letters 28, 31–36. https://doi.org/10.7185/geochemlet.2341

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The pronounced Mo isotope anomalies observed for a Ryugu sample has been explained in a similar manner (Nakanishi et al., 2023).
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Nanne, J.A.M., Nimmo, F., Cuzzi, J.N., Kleine, T. (2019) Origin of the non-carbonaceous–carbonaceous meteorite dichotomy. Earth and Planetary Science Letters 511, 44–54. https://doi.org/10.1016/j.epsl.2019.01.027

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Importantly, as is evident for instance from the distinct O isotope composition of the Sun (McKeegan et al., 2011) for mass independent isotope anomalies, the isotopic composition of the solar system may be markedly different from that of CI chondrites, which likely was established by mixing of isotopically distinct materials during the formation and dynamical evolution of the protoplanetary disk (e.g., Nanne et al., 2019).
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Nie, N.X., Chen, X.-Y., Hopp, T., Hu, J.Y., Zhang, Z.J., Teng, F.-Z., Shahar, A., Dauphas, N. (2021) Imprint of chondrule formation on the K and Rb isotopic compositions of carbonaceous meteorites. Science Advances 7, eabl3929. https://doi.org/10.1126/sciadv.abl3929

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Variations in the abundance of these two components result in correlations among the concentrations and mass dependent isotopic compositions of the MVEs, including Ge (Wölfer et al., 2025a), Te (Hellmann et al., 2020), Zn (e.g., Pringle et al., 2017), Rb (e.g., Nie et al., 2021), K (e.g., Koefoed et al., 2023), and Cd (Morton et al., 2024).
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Noguchi, T., Matsumoto, T., Miyake, A., Igami, Y., Haruta, M. et al. (2023) A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu. Nature Astronomy 7, 170–181. https://doi.org/10.1038/s41550-022-01841-6

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These higher MVE concentrations can partly or wholly be accounted for by the >6 wt. % lower water content of Ryugu samples compared to CI chondrites, and ultimately might stem from the incorporation of terrestrial water into CI meteorites and/or the loss of water from Ryugu’s surface during space weathering (Noguchi et al., 2023; Yokoyama et al., 2023a).
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Palme, H., O’Neill, H.St.C. (2014) 3.1 - Cosmochemical Estimates of Mantle Composition. In: Holland, H.D., Turekian, K.K. (Eds.) Treatise on Geochemistry. Second Edition, Elsevier, Amsterdam, 1–39. https://doi.org/10.1016/B978-0-08-095975-7.00201-1

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As such, CI chondrites are commonly taken to represent the bulk chemical composition of the solar system (e.g., Palme and O’Neill, 2014).
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Paquet, M., Moynier, F., Yokoyama, T., Dai, W., Hu, Y. et al. (2023) Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis. Nature Astronomy 7, 182–189. https://doi.org/10.1038/s41550-022-01846-1

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However, while Ryugu and Orgueil, the most commonly analysed CI chondrite, have indistinguishable mass dependent isotopic composition of the MVEs Zn (Paquet et al., 2023) and K (Hu et al., 2024), these compositions also overlap with those of other volatile-rich carbonaceous chondrites and, therefore, do not provide a clear link between CI chondrites and Ryugu.
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Moreover, while Ryugu samples exhibit nucleosynthetic Zn isotope anomalies similar to CI chondrites, these compositions overlap with those of other carbonaceous chondrites (Paquet et al., 2023).
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Consistent with Paquet et al. (2023), we find no δ^66/64Zn differences among Ryugu sample A0220, Orgueil, Tagish Lake, and Tarda, despite their different Zn contents.
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Compared to CI chondrites, Ryugu sample A0220 is enriched in Ge, Te, and Zn by ∼5–10 %, consistent with the ∼10 % higher Zn concentrations found in prior studies (Paquet et al., 2023; Yokoyama et al., 2023a).
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The only other study on Zn isotope anomalies in Ryugu only reported μ⁶⁶Zn values using the ⁶⁸Zn/⁶⁴Zn normalisation (Paquet et al., 2023), which results in overall smaller anomalies than the ⁶⁷Zn/⁶⁴Zn normalisation.
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The same conclusion was reached previously based on Zn isotopes (Paquet et al., 2023), but we emphasise that only for Ge and Te are the isotopic compositions of Ryugu and CI chondrites distinct from those of other volatile-rich carbonaceous chondrites.
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Pringle, E.A., Moynier, F., Beck, P., Paniello, R., Hezel, D.C. (2017) The origin of volatile element depletion in early solar system material: Clues from Zn isotopes in chondrules. Earth and Planetary Science Letters 468, 62–71. https://doi.org/10.1016/j.epsl.2017.04.002

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Variations in the abundance of these two components result in correlations among the concentrations and mass dependent isotopic compositions of the MVEs, including Ge (Wölfer et al., 2025a), Te (Hellmann et al., 2020), Zn (e.g., Pringle et al., 2017), Rb (e.g., Nie et al., 2021), K (e.g., Koefoed et al., 2023), and Cd (Morton et al., 2024).
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For instance, mass dependent Zn isotope variations have been observed among the components of chondrites (Luck et al., 2005; Pringle et al., 2017), and so over- or under-sampling of certain components having distinct isotopic compositions may have occurred.
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Savage, P.S., Moynier, F., Boyet, M. (2022) Zinc isotope anomalies in primitive meteorites identify the outer solar system as an important source of Earth’s volatile inventory. Icarus 386, 115172. https://doi.org/10.1016/j.icarus.2022.115172

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Among the MVEs, Zn also shows nucleosynthetic isotope anomalies, but until now no isotopic variations among the carbonaceous chondrites have been identified (Savage et al., 2022; Steller et al., 2022; Martins et al., 2023).
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Schneider, J.M., Burkhardt, C., Kleine, T. (2023) Distribution of s-, r-, and p-process Nuclides in the Early Solar System Inferred from Sr Isotope Anomalies in Meteorites. The Astrophysical Journal Letters 952, L25. https://doi.org/10.3847/2041-8213/ace187

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The Orgueil sample analysed in this study is an aliquot from a ∼0.7 g powder prepared in a prior study (Schneider et al., 2023).
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Spitzer, F., Kleine, T., Burkhardt, C., Hopp, T., Yokoyama, T. et al. (2024) The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites. Science Advances 10, eadp2426. https://doi.org/10.1126/sciadv.adp2426

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Among the carbonaceous chondrites, CI chondrites exhibit unique nucleosynthetic isotope signatures for Fe and Ni (Hopp et al., 2022; Spitzer et al., 2024) and also show distinct mass dependent isotope compositions for the moderately volatile elements (MVEs; those that condense from a solar gas between ∼1250 and 650 K).
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A genetic link between asteroid Ryugu and CI chondrites has been established in numerous studies, based on for instance nucleosynthetic isotope anomalies in the non-volatile elements Cr, Ti, Fe, and Ni (Hopp et al., 2022; Yokoyama et al., 2023a, 2023b; Spitzer et al., 2024).
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For instance, different Ryugu subsamples exhibit variable Cr, Ti, and Ni nucleosynthetic isotope signatures (Yokoyama et al., 2023a, 2023b; Spitzer et al., 2024), which at least in part have been attributed to the redistribution of isotopically anomalous phases during aqueous alteration in the parent body (Yokoyama et al., 2023b).
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Steller, T., Burkhardt, C., Yang, C., Kleine, T. (2022) Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles. Icarus 386, 115171. https://doi.org/10.1016/j.icarus.2022.115171

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The sample digestion, chemical separation and isotope measurements of Ge, Te, and Zn followed our previously established procedures (Hellmann et al., 2020; Steller et al., 2022; Wölfer et al., 2025a,b) and are described in the Supplementary Information
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Mass independent Zn isotope data previously published in Steller et al. (2022).
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Literature data from Steller et al. (2022).
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Among the MVEs, Zn also shows nucleosynthetic isotope anomalies, but until now no isotopic variations among the carbonaceous chondrites have been identified (Savage et al., 2022; Steller et al., 2022; Martins et al., 2023).
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We find identical μ⁶⁶Zn values for two separate analyses of Orgueil (μ⁶⁶Zn = 36 ± 5 in Steller et al., 2022, and 36 ± 2 in this study) and Ryugu sample A0220 (μ⁶⁶Zn = 36 ± 2).
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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

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Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 mission returned 5.4 g of sample of the Cb-type asteroid 162173 Ryugu to Earth (Tachibana et al., 2022; Yada et al., 2022).
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Wölfer, E., Burkhardt, C., Nimmo, F., Kleine, T. (2025a) Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites. Earth and Planetary Science Letters 663, 119435. https://doi.org/10.1016/j.epsl.2025.119435

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Both elements have been shown to display large and systematic mass dependent isotopic variations among the carbonaceous chondrites, where CI chondrites are characterised by the highest Ge and Te concentrations and strongest heavy isotope enrichments (Hellmann et al., 2020; Wölfer et al., 2025a).
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Finally, for direct comparison we also analysed aliquots of the large, homogenised MS-A powder of the CV3 chondrite Allende, which has previously been analysed for Ge and Te isotopes using the same analytical setup as in this study (Hellmann et al., 2020; Wölfer et al., 2025a).
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The sample digestion, chemical separation and isotope measurements of Ge, Te, and Zn followed our previously established procedures (Hellmann et al., 2020; Steller et al., 2022; Wölfer et al., 2025a,b) and are described in the Supplementary Information
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Literature data for Ge is from Wölfer et al. (2025a); data for Te is from Hellmann et al. (2020, 2023) and Morton et al. (2024).
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Variations in the abundance of these two components result in correlations among the concentrations and mass dependent isotopic compositions of the MVEs, including Ge (Wölfer et al., 2025a), Te (Hellmann et al., 2020), Zn (e.g., Pringle et al., 2017), Rb (e.g., Nie et al., 2021), K (e.g., Koefoed et al., 2023), and Cd (Morton et al., 2024).
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By contrast, for Ge, these variations amount to only ∼3 % of the overall δ^74/70Ge variability among the carbonaceous chondrites (Wölfer et al., 2025a), and the difference between CI chondrites and Tagish Lake itself is about four times larger than the heterogeneity observed among the CI chondrite and Ryugu samples.
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Wölfer, E., Burkhardt, C., Kleine, T. (2025b) Germanium stable isotope measurements by double-spike MC-ICPMS. Journal of Analytical Atomic Spectrometry 40, 1023–1036. https://doi.org/10.1039/D4JA00359D

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The sample digestion, chemical separation and isotope measurements of Ge, Te, and Zn followed our previously established procedures (Hellmann et al., 2020; Steller et al., 2022; Wölfer et al., 2025a,b) and are described in the Supplementary Information
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For Ge and Te, the instrumental mass bias was corrected using ⁷⁰Ge–⁷³Ge (Wölfer et al., 2025b) and ¹²³Te–¹²⁵Te double spikes (Hellmann et al., 2020), and the data are reported as the per mille deviations from certified standard solutions (see Table 1 for definitions).
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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

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Japan Aerospace Exploration Agency’s (JAXA) Hayabusa2 mission returned 5.4 g of sample of the Cb-type asteroid 162173 Ryugu to Earth (Tachibana et al., 2022; Yada et al., 2022).
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Yokoyama, T., Nagashima, K., Nakai, I., Young, E.D., Abe, Y. et al. (2023a) Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites. Science 379, eabn7850. https://doi.org/10.1126/science.abn7850

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Initial analyses of the returned samples have revealed that Ryugu is petrologically, mineralogically, chemically, and isotopically similar to the Ivuna-type (CI) chondrites (Nakamura et al., 2023; Yokoyama et al., 2023a,b).
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Compared to CI chondrites, Ryugu sample A0220 is enriched in Ge, Te, and Zn by ∼5–10 %, consistent with the ∼10 % higher Zn concentrations found in prior studies (Paquet et al., 2023; Yokoyama et al., 2023a).
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These higher MVE concentrations can partly or wholly be accounted for by the >6 wt. % lower water content of Ryugu samples compared to CI chondrites, and ultimately might stem from the incorporation of terrestrial water into CI meteorites and/or the loss of water from Ryugu’s surface during space weathering (Noguchi et al., 2023; Yokoyama et al., 2023a).
View in article
A genetic link between asteroid Ryugu and CI chondrites has been established in numerous studies, based on for instance nucleosynthetic isotope anomalies in the non-volatile elements Cr, Ti, Fe, and Ni (Hopp et al., 2022; Yokoyama et al., 2023a, 2023b; Spitzer et al., 2024).
View in article
For instance, different Ryugu subsamples exhibit variable Cr, Ti, and Ni nucleosynthetic isotope signatures (Yokoyama et al., 2023a, 2023b; Spitzer et al., 2024), which at least in part have been attributed to the redistribution of isotopically anomalous phases during aqueous alteration in the parent body (Yokoyama et al., 2023b).
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Yokoyama, T., Wadhwa, M., Iizuka, T., Rai, V., Gautam, I. et al. (2023b) Water circulation in Ryugu asteroid affected the distribution of nucleosynthetic isotope anomalies in returned sample. Science Advances 9, eadi7048. https://doi.org/10.1126/sciadv.adi7048

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Initial analyses of the returned samples have revealed that Ryugu is petrologically, mineralogically, chemically, and isotopically similar to the Ivuna-type (CI) chondrites (Nakamura et al., 2023; Yokoyama et al., 2023a,b).
View in article
A genetic link between asteroid Ryugu and CI chondrites has been established in numerous studies, based on for instance nucleosynthetic isotope anomalies in the non-volatile elements Cr, Ti, Fe, and Ni (Hopp et al., 2022; Yokoyama et al., 2023a, 2023b; Spitzer et al., 2024).
View in article
For instance, different Ryugu subsamples exhibit variable Cr, Ti, and Ni nucleosynthetic isotope signatures (Yokoyama et al., 2023a, 2023b; Spitzer et al., 2024), which at least in part have been attributed to the redistribution of isotopically anomalous phases during aqueous alteration in the parent body (Yokoyama et al., 2023b).
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