Leroux, Hugues, Le Guillou, Corentin, Marinova, Maya, Laforet, Sylvain, Viennet, Jean‐Christophe, Mouloud, Bahae‐Eddine, Teurtrie, Adrien, de la Peña, Francisco, Jacob, Damien, Hallatt, Daniel, and others. (2023) Phyllosilicates with embedded Fe‐based nanophases in Ryugu and Orgueil. Meteoritics & Planetary Science, 59 (8). pp. 1947-1965. ISSN 1086-9379. E-ISSN 1945-5100. (doi:10.1111/maps.14101) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:104052)
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| Official URL: https://doi.org/10.1111/maps.14101 |
Abstract
Samples were recently collected from the carbonaceous asteroid (162173) Ryugu, by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 mission. They resemble CI chondrites material, thus showing clear evidence of extensive aqueous alteration attested by the widespread presence of a mixture of serpentine and saponite. We present here a scanning transmission electron microscopy study of the Ryugu dominant lithology of the phyllosilicate matrix at the nanometer scale, which we compare with that of the Orgueil CI chondrite. In both objects, the phyllosilicates are of comparable nature and texture, consisting of a mixture of small‐sized crystallites of serpentine and saponite. At the micrometer scale or less, the texture is an alternation of fine and coarse domains. The fine‐grained regions are dominated by saponite. In Ryugu, they enclose numerous Fe,Ni nanosulfides, whereas in Orgueil, S‐ and Ni‐rich ferrihydrite is abundant. The coarse‐grained regions contain more serpentine and no or little Fe,Ni sulfides or ferrihydrite. Scanning transmission x‐ray microscopy at the Fe‐L3 edge also reveals that iron valency of phyllosilicates is higher and more homogeneous in Orgueil (~70% Fe3+) than in Ryugu (<50% Fe3+). We interpret the observed textures as being mostly a consequence of aqueous alteration, likely resulting from the replacement by phyllosilicates of submicrometric components, initially agglomerated by a primary accretion. The fine‐grained domains may result from the replacement of GEMS (GEMS—glass with embedded metal and sulfides) objects or from other types of nanometric assemblages of silicate and Fe‐based nanophases. On the other hand, the coarse‐grained regions may correspond to the replacement of anhydrous crystalline silicates of the olivine and pyroxene type. The major difference is the presence of Fe,Ni sulfides in Ryugu and of ferrihydrite and higher iron valency of phyllosilicates in Orgueil. This might be due to long‐term terrestrial weathering that would have destabilized the nanosulfides. We also explore an alternative scenario involving more oxidizing hydrothermal conditions on the Orgueil parent body.
| Item Type: | Article |
|---|---|
| DOI/Identification number: | 10.1111/maps.14101 |
| Uncontrolled keywords: | Space and Planetary Science, Geophysics |
| Subjects: |
Q Science Q Science > QC Physics |
| Divisions: | Divisions > Division of Natural Sciences > Physics and Astronomy |
| Funders: |
Agence Nationale de la Recherche (https://ror.org/00rbzpz17)
European Research Council (https://ror.org/0472cxd90) Japan Society for the Promotion of Science London (https://ror.org/02m7axw05) |
| SWORD Depositor: | JISC Publications Router |
| Depositing User: | JISC Publications Router |
| Date Deposited: | 15 Mar 2024 14:43 UTC |
| Last Modified: | 05 Nov 2024 13:09 UTC |
| Resource URI: | https://kar.kent.ac.uk/id/eprint/104052 (The current URI for this page, for reference purposes) |
University of Kent Author Information
Hallatt, Daniel.
| Creator's ORCID: |
 https://orcid.org/0000-0002-4426-9891
|
|---|---|
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