A unifying model for the accretion of chondrules and matrix
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The so far unique role of our Solar System in the universe regarding its capacity for life raises fundamental questions about its formation history relative to exoplanetary systems. Central in this research is the accretion of asteroids and planets from a gas-rich circumstellar disk and the final distribution of their mass around the Sun. The key building blocks of the planets may be represented by chondrules, the main constituents of chondritic meteorites, which in turn are primitive fragments of planetary bodies. Chondrule formation mechanisms, as well as their subsequent storage and transport in the disk, are still poorly understood, and their origin and evolution can be probed through their link (i.e., complementary or noncomplementary) to fine-grained dust (matrix) that accreted together with chondrules. Here, we investigate the apparent chondrule–matrix complementarity by analyzing major, minor, and trace element compositions of chondrules and matrix in altered and relatively unaltered CV, CM, and CR (Vigarano-type, Mighei-type, and Renazzo-type) chondrites. We show that matrices of the most unaltered CM and CV chondrites are overall CI-like (Ivuna-type) (similar to solar composition) and do not reflect any volatile enrichment or elemental patterns complementary to chondrules, the exception being their Fe/Mg ratios. We propose to unify these contradictory data by invoking a chondrule formation model in which CI-like dust accreted to so-called armored chondrules, which are ubiquitous in many chondrites. Metal rims expelled during chondrule formation, but still attached to their host chondrule, interacted with the accreted matrix, thereby enriching the matrix in siderophile elements and generating an apparent complementarity.
| Originalsprog | Engelsk |
|---|---|
| Tidsskrift | PNAS |
| Vol/bind | 116 |
| Udgave nummer | 38 |
| Sider (fra-til) | 18860-18866 |
| Antal sider | 7 |
| ISSN | 0027-8424 |
| DOI | |
| Status | Udgivet - 2019 |
| Eksternt udgivet | Ja |
Bibliografisk note
Funding Information:
We thank 3 anonymous referees for their thoughtful suggestions that have improved this manuscript. This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Marie Skłodowska-Curie Grant 786081. F.M. thanks the European Research Council (ERC) for funding under the European Community’s H2020 Framework Programme/ERC Grant 637503 (Pristine) and the French National Research Agency (ANR) for Chaire d’Excellence Sorbonne Paris Cité Grant IDEX13C445 and for UnivEarthS Labex Program Grants ANR-10-LABX-0023 and ANR-11-IDEX-0005-02. Parts of this work were supported by the IPGP multidisciplinary program Plateforme d’analyse haute résolution and by Region Île-deFrance SESAME Grant 12015908. We thank the Natural History Museum of Denmark for the generous loan of thick sections from Leoville, Maribo, and NWA801. We greatly appreciate the assistance of Bleuenn Gueguen in the operation of the LA-ICPMS and Stephen Borensztajn for the SEM.
Funding Information:
ACKNOWLEDGMENTS. We thank 3 anonymous referees for their thoughtful suggestions that have improved this manuscript. This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Marie Skłodowska-Curie Grant 786081. F.M. thanks the European Research Council (ERC) for funding under the European Community’s H2020 Framework Programme/ERC Grant 637503 (Pristine) and the French National Research Agency (ANR) for Chaire d’Excellence Sorbonne Paris Cité Grant IDEX13C445 and for Uni-vEarthS Labex Program Grants ANR-10-LABX-0023 and ANR-11-IDEX-0005-02. Parts of this work were supported by the IPGP multidisciplinary program Plateforme d’analyse haute résolution and by Region ˆle-de-France SESAME Grant 12015908. We thank the Natural History Museum of Denmark for the generous loan of thick sections from Leoville, Maribo, and NWA801. We greatly appreciate the assistance of Bleuenn Gueguen in the operation of the LA-ICPMS and Stephen Borensztajn for the SEM.
Publisher Copyright:
© 2019 National Academy of Sciences. All rights reserved.
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