Tracing the origin and core formation of the enstatite achondrite parent bodies using Cr isotopes

Ke Zhu (朱柯); Frédéric Moynier; Martin Schiller; Harry Becker; Jean Alix Barrat; Martin Bizzarro

doi:10.1016/j.gca.2021.05.053

Tracing the origin and core formation of the enstatite achondrite parent bodies using Cr isotopes

Ke Zhu (朱柯)^*, Frédéric Moynier, Martin Schiller, Harry Becker, Jean Alix Barrat, Martin Bizzarro

^*Corresponding author for this work

School of Earth Sciences

Research output: Contribution to journal › Article (Academic Journal) › peer-review

19 Citations (Scopus)

Abstract

Enstatite achondrites (including aubrites) are the only differentiated meteorites that have similar isotope compositions to the Earth-Moon system for most of the elements. However, the origin and differentiation of enstatite achondrites and their parent bodies remain poorly understood. Here, we report high-precision mass-independent and mass-dependent Cr isotope data for 10 enstatite achondrites, including eight aubrites, Itqiy and one enstatite-rich clast in Almahatta Sitta, to further constrain the origin and evolution of their parent bodies. The ε⁵⁴Cr (per 10,000 deviation of the mass bias corrected ⁵⁴Cr/⁵²Cr ratio from a terrestrial standard) systematics define three groups: main-group aubrites with ε⁵⁴Cr = 0.06 ± 0.12 (2SD, N = 7) that is similar to the enstatite chondrites and the Earth-Moon system, Shallowater aubrite with ε⁵⁴Cr = −0.12 ± 0.04 and Itqiy-type meteorites with ε⁵⁴Cr = −0.26 ± 0.03 (2SD, N = 2). This shows that there were at least three enstatite achondrite parent bodies in the Solar System. This is confirmed by their distinguished mass-dependent Cr isotope compositions (δ⁵³Cr values): 0.24 ± 0.03‰, 0.10 ± 0.03‰ and −0.03 ± 0.03‰ for main-group, Shallowater and Itqiy parent bodies, respectively. Aubrites are isotopically heavier than chondrites (δ⁵³Cr = −0.12 ± 0.04‰), which likely results from the formation of an isotopically light sulfur-rich core. We also obtained the abundance of the radiogenic ⁵³Cr (produced by the radioactive decay of ⁵³Mn, T_1/2 = 3.7 million years). The radiogenic ε⁵³Cr excesses correlate with the ⁵⁵Mn/⁵²Cr ratios for aubrites (except Shallowater and Bustee) and also the Cr stable isotope compositions (δ⁵³Cr values). We show that these correlations represent mixing lines that also hold chronological significance since they are controlled by the crystallization of sulfides and silicates, which mostly reflect the main-group aubrite parent body differentiation at 4562.5 ± 1.1 Ma (i.e., 4.8 ± 1.1 Ma after Solar System formation). Furthermore, the intercept of these lines with the ordinate axis which represent the initial ε⁵³Cr value of main-group aubrites (0.50 ± 0.16, 2σ) is much higher than the average ε⁵³Cr value of enstatite chondrites (0.15 ± 0.10, 2SD), suggesting an early sulfur-rich core formation that effectively increased the Mn/Cr ratio of the silicate fraction of the main-group aubrite parent body.

Original language	English
Pages (from-to)	256-272
Number of pages	17
Journal	Geochimica et Cosmochimica Acta
Volume	308
DOIs	https://doi.org/10.1016/j.gca.2021.05.053
Publication status	Published - 1 Sept 2021

Bibliographical note

Funding Information:
Constructive comments from Jan Render, Royji Tanaka and Rick Carlson greatly improved this manuscript, and comments and editorial handling from the associate editor Yves Marrocchi are also appreciated. F. M. acknowledges funding from the European Research Council under the H2020 framework program/ERC Starting Grant Agreement (#637503–PRISTINE) and financial support of the UnivEarthS Labex program at Sorbonne Paris Cité (#ANR–10–LABX–0023 and #ANR–11–IDEX-0005-02), and the ANR through a chaire d’excellence Sorbonne Paris Cité. M. B. acknowledges funding the Carlsberg Foundation (CF18-1105), the Danish National Research Foundation (DNRF97) and the European Research Council (ERC Advanced Grant Agreement, #833275–DEEPTIME). M. S. acknowledges funding from the Villum Fonden (#00025333). Parts of this work were supported by IPGP multidisciplinary program PARI, and by Paris–IdF region SESAME (#12015908). Pierre Burckel and Pascale Louvat were appreciated for analysis on ICP-MS and MC-ICP-MS at IPGP, respectively. We thank Ninja Braukmüller, Monika Feth, Maren Saenz, Elis Hoffmann and Yogita Kadlag for technical support at FUB. Discussions with Paolo Sossi about Cr stable isotope fractionation in S-rich core formation helped us interpret the data. K. Z. thanks an Alexander von Humboldt fellowship (for postdoc researchers), China Scholarship Council (CSC) for a PhD fellowship (#201706340161) and guest fellowships from TRR 170 (host: Harry Becker) and Nanjing University (host: Hejiu Hui) during his stay in Berlin (2020 autumn) and Nanjing (2021 Spring) respectively. H.B. is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation–#263649064–TRR 170). This is TRR 170 publication no. 135.

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

Mn-Cr chronometry
Cr systematics
Aubrites
Core formation
Cr stable isotopes
Enstatite achondrites
Mantle differentiation
Reduced planets

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@article{3429fcfcef6346069f66d4b35568bbc2,

title = "Tracing the origin and core formation of the enstatite achondrite parent bodies using Cr isotopes",

abstract = "Enstatite achondrites (including aubrites) are the only differentiated meteorites that have similar isotope compositions to the Earth-Moon system for most of the elements. However, the origin and differentiation of enstatite achondrites and their parent bodies remain poorly understood. Here, we report high-precision mass-independent and mass-dependent Cr isotope data for 10 enstatite achondrites, including eight aubrites, Itqiy and one enstatite-rich clast in Almahatta Sitta, to further constrain the origin and evolution of their parent bodies. The ε54Cr (per 10,000 deviation of the mass bias corrected 54Cr/52Cr ratio from a terrestrial standard) systematics define three groups: main-group aubrites with ε54Cr = 0.06 ± 0.12 (2SD, N = 7) that is similar to the enstatite chondrites and the Earth-Moon system, Shallowater aubrite with ε54Cr = −0.12 ± 0.04 and Itqiy-type meteorites with ε54Cr = −0.26 ± 0.03 (2SD, N = 2). This shows that there were at least three enstatite achondrite parent bodies in the Solar System. This is confirmed by their distinguished mass-dependent Cr isotope compositions (δ53Cr values): 0.24 ± 0.03‰, 0.10 ± 0.03‰ and −0.03 ± 0.03‰ for main-group, Shallowater and Itqiy parent bodies, respectively. Aubrites are isotopically heavier than chondrites (δ53Cr = −0.12 ± 0.04‰), which likely results from the formation of an isotopically light sulfur-rich core. We also obtained the abundance of the radiogenic 53Cr (produced by the radioactive decay of 53Mn, T1/2 = 3.7 million years). The radiogenic ε53Cr excesses correlate with the 55Mn/52Cr ratios for aubrites (except Shallowater and Bustee) and also the Cr stable isotope compositions (δ53Cr values). We show that these correlations represent mixing lines that also hold chronological significance since they are controlled by the crystallization of sulfides and silicates, which mostly reflect the main-group aubrite parent body differentiation at 4562.5 ± 1.1 Ma (i.e., 4.8 ± 1.1 Ma after Solar System formation). Furthermore, the intercept of these lines with the ordinate axis which represent the initial ε53Cr value of main-group aubrites (0.50 ± 0.16, 2σ) is much higher than the average ε53Cr value of enstatite chondrites (0.15 ± 0.10, 2SD), suggesting an early sulfur-rich core formation that effectively increased the Mn/Cr ratio of the silicate fraction of the main-group aubrite parent body.",

keywords = "Mn-Cr chronometry, Cr systematics, Aubrites, Core formation, Cr stable isotopes, Enstatite achondrites, Mantle differentiation, Reduced planets",

author = "{Zhu (朱柯)}, Ke and Fr{\'e}d{\'e}ric Moynier and Martin Schiller and Harry Becker and Barrat, {Jean Alix} and Martin Bizzarro",

note = "Funding Information: Constructive comments from Jan Render, Royji Tanaka and Rick Carlson greatly improved this manuscript, and comments and editorial handling from the associate editor Yves Marrocchi are also appreciated. F. M. acknowledges funding from the European Research Council under the H2020 framework program/ERC Starting Grant Agreement (#637503–PRISTINE) and financial support of the UnivEarthS Labex program at Sorbonne Paris Cit{\'e} (#ANR–10–LABX–0023 and #ANR–11–IDEX-0005-02), and the ANR through a chaire d{\textquoteright}excellence Sorbonne Paris Cit{\'e}. M. B. acknowledges funding the Carlsberg Foundation (CF18-1105), the Danish National Research Foundation (DNRF97) and the European Research Council (ERC Advanced Grant Agreement, #833275–DEEPTIME). M. S. acknowledges funding from the Villum Fonden (#00025333). Parts of this work were supported by IPGP multidisciplinary program PARI, and by Paris–IdF region SESAME (#12015908). Pierre Burckel and Pascale Louvat were appreciated for analysis on ICP-MS and MC-ICP-MS at IPGP, respectively. We thank Ninja Braukm{\"u}ller, Monika Feth, Maren Saenz, Elis Hoffmann and Yogita Kadlag for technical support at FUB. Discussions with Paolo Sossi about Cr stable isotope fractionation in S-rich core formation helped us interpret the data. K. Z. thanks an Alexander von Humboldt fellowship (for postdoc researchers), China Scholarship Council (CSC) for a PhD fellowship (#201706340161) and guest fellowships from TRR 170 (host: Harry Becker) and Nanjing University (host: Hejiu Hui) during his stay in Berlin (2020 autumn) and Nanjing (2021 Spring) respectively. H.B. is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation–#263649064–TRR 170). This is TRR 170 publication no. 135. Publisher Copyright: {\textcopyright} 2021 Elsevier Ltd",

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doi = "10.1016/j.gca.2021.05.053",

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TY - JOUR

T1 - Tracing the origin and core formation of the enstatite achondrite parent bodies using Cr isotopes

AU - Zhu (朱柯), Ke

AU - Moynier, Frédéric

AU - Schiller, Martin

AU - Becker, Harry

AU - Barrat, Jean Alix

AU - Bizzarro, Martin

N1 - Funding Information: Constructive comments from Jan Render, Royji Tanaka and Rick Carlson greatly improved this manuscript, and comments and editorial handling from the associate editor Yves Marrocchi are also appreciated. F. M. acknowledges funding from the European Research Council under the H2020 framework program/ERC Starting Grant Agreement (#637503–PRISTINE) and financial support of the UnivEarthS Labex program at Sorbonne Paris Cité (#ANR–10–LABX–0023 and #ANR–11–IDEX-0005-02), and the ANR through a chaire d’excellence Sorbonne Paris Cité. M. B. acknowledges funding the Carlsberg Foundation (CF18-1105), the Danish National Research Foundation (DNRF97) and the European Research Council (ERC Advanced Grant Agreement, #833275–DEEPTIME). M. S. acknowledges funding from the Villum Fonden (#00025333). Parts of this work were supported by IPGP multidisciplinary program PARI, and by Paris–IdF region SESAME (#12015908). Pierre Burckel and Pascale Louvat were appreciated for analysis on ICP-MS and MC-ICP-MS at IPGP, respectively. We thank Ninja Braukmüller, Monika Feth, Maren Saenz, Elis Hoffmann and Yogita Kadlag for technical support at FUB. Discussions with Paolo Sossi about Cr stable isotope fractionation in S-rich core formation helped us interpret the data. K. Z. thanks an Alexander von Humboldt fellowship (for postdoc researchers), China Scholarship Council (CSC) for a PhD fellowship (#201706340161) and guest fellowships from TRR 170 (host: Harry Becker) and Nanjing University (host: Hejiu Hui) during his stay in Berlin (2020 autumn) and Nanjing (2021 Spring) respectively. H.B. is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation–#263649064–TRR 170). This is TRR 170 publication no. 135. Publisher Copyright: © 2021 Elsevier Ltd

PY - 2021/9/1

Y1 - 2021/9/1

N2 - Enstatite achondrites (including aubrites) are the only differentiated meteorites that have similar isotope compositions to the Earth-Moon system for most of the elements. However, the origin and differentiation of enstatite achondrites and their parent bodies remain poorly understood. Here, we report high-precision mass-independent and mass-dependent Cr isotope data for 10 enstatite achondrites, including eight aubrites, Itqiy and one enstatite-rich clast in Almahatta Sitta, to further constrain the origin and evolution of their parent bodies. The ε54Cr (per 10,000 deviation of the mass bias corrected 54Cr/52Cr ratio from a terrestrial standard) systematics define three groups: main-group aubrites with ε54Cr = 0.06 ± 0.12 (2SD, N = 7) that is similar to the enstatite chondrites and the Earth-Moon system, Shallowater aubrite with ε54Cr = −0.12 ± 0.04 and Itqiy-type meteorites with ε54Cr = −0.26 ± 0.03 (2SD, N = 2). This shows that there were at least three enstatite achondrite parent bodies in the Solar System. This is confirmed by their distinguished mass-dependent Cr isotope compositions (δ53Cr values): 0.24 ± 0.03‰, 0.10 ± 0.03‰ and −0.03 ± 0.03‰ for main-group, Shallowater and Itqiy parent bodies, respectively. Aubrites are isotopically heavier than chondrites (δ53Cr = −0.12 ± 0.04‰), which likely results from the formation of an isotopically light sulfur-rich core. We also obtained the abundance of the radiogenic 53Cr (produced by the radioactive decay of 53Mn, T1/2 = 3.7 million years). The radiogenic ε53Cr excesses correlate with the 55Mn/52Cr ratios for aubrites (except Shallowater and Bustee) and also the Cr stable isotope compositions (δ53Cr values). We show that these correlations represent mixing lines that also hold chronological significance since they are controlled by the crystallization of sulfides and silicates, which mostly reflect the main-group aubrite parent body differentiation at 4562.5 ± 1.1 Ma (i.e., 4.8 ± 1.1 Ma after Solar System formation). Furthermore, the intercept of these lines with the ordinate axis which represent the initial ε53Cr value of main-group aubrites (0.50 ± 0.16, 2σ) is much higher than the average ε53Cr value of enstatite chondrites (0.15 ± 0.10, 2SD), suggesting an early sulfur-rich core formation that effectively increased the Mn/Cr ratio of the silicate fraction of the main-group aubrite parent body.

AB - Enstatite achondrites (including aubrites) are the only differentiated meteorites that have similar isotope compositions to the Earth-Moon system for most of the elements. However, the origin and differentiation of enstatite achondrites and their parent bodies remain poorly understood. Here, we report high-precision mass-independent and mass-dependent Cr isotope data for 10 enstatite achondrites, including eight aubrites, Itqiy and one enstatite-rich clast in Almahatta Sitta, to further constrain the origin and evolution of their parent bodies. The ε54Cr (per 10,000 deviation of the mass bias corrected 54Cr/52Cr ratio from a terrestrial standard) systematics define three groups: main-group aubrites with ε54Cr = 0.06 ± 0.12 (2SD, N = 7) that is similar to the enstatite chondrites and the Earth-Moon system, Shallowater aubrite with ε54Cr = −0.12 ± 0.04 and Itqiy-type meteorites with ε54Cr = −0.26 ± 0.03 (2SD, N = 2). This shows that there were at least three enstatite achondrite parent bodies in the Solar System. This is confirmed by their distinguished mass-dependent Cr isotope compositions (δ53Cr values): 0.24 ± 0.03‰, 0.10 ± 0.03‰ and −0.03 ± 0.03‰ for main-group, Shallowater and Itqiy parent bodies, respectively. Aubrites are isotopically heavier than chondrites (δ53Cr = −0.12 ± 0.04‰), which likely results from the formation of an isotopically light sulfur-rich core. We also obtained the abundance of the radiogenic 53Cr (produced by the radioactive decay of 53Mn, T1/2 = 3.7 million years). The radiogenic ε53Cr excesses correlate with the 55Mn/52Cr ratios for aubrites (except Shallowater and Bustee) and also the Cr stable isotope compositions (δ53Cr values). We show that these correlations represent mixing lines that also hold chronological significance since they are controlled by the crystallization of sulfides and silicates, which mostly reflect the main-group aubrite parent body differentiation at 4562.5 ± 1.1 Ma (i.e., 4.8 ± 1.1 Ma after Solar System formation). Furthermore, the intercept of these lines with the ordinate axis which represent the initial ε53Cr value of main-group aubrites (0.50 ± 0.16, 2σ) is much higher than the average ε53Cr value of enstatite chondrites (0.15 ± 0.10, 2SD), suggesting an early sulfur-rich core formation that effectively increased the Mn/Cr ratio of the silicate fraction of the main-group aubrite parent body.

KW - Mn-Cr chronometry

KW - Cr systematics

KW - Aubrites

KW - Core formation

KW - Cr stable isotopes

KW - Enstatite achondrites

KW - Mantle differentiation

KW - Reduced planets

UR - http://www.scopus.com/inward/record.url?scp=85108651795&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2021.05.053

DO - 10.1016/j.gca.2021.05.053

M3 - Article (Academic Journal)

AN - SCOPUS:85108651795

SN - 0016-7037

VL - 308

SP - 256

EP - 272

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

ER -

Tracing the origin and core formation of the enstatite achondrite parent bodies using Cr isotopes

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