Nebular thermal processing of accretionary fine-grained rims in the Paris CM chondrite

Autor: Corentin Le Guillou, Hugues Leroux, Pierre-Marie Zanetta, B. Zanda, R. H. Hewins
Přispěvatelé: Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Planetary Sciences [Piscataway], Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers), Department of Mineral Sciences of the Smithsonian 117733-85276-1 11356-115900-114887-R2460, French RENATECH network, Region Hauts-de-France, European Commission, Chevreul Institute, Centre National D'etudes Spatiales, Programme National de Planetologie (PNP) of CNRS/INSU, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centrale Lille Institut (CLIL), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Materials science
010504 meteorology & atmospheric sciences
Mineralogy
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]
Pyroxene
engineering.material
010502 geochemistry & geophysics
01 natural sciences
Texture (geology)
Matrix (geology)
chemistry.chemical_compound
Geochemistry and Petrology
Chondrite
0105 earth and related environmental sciences
Olivine
Mineral
Matrix
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
Chondrule
Amorphous silicates
[CHIM.MATE]Chemical Sciences/Material chemistry
ACADEMY
Silicate
chemistry
engineering
[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Chondrites
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Fine-grained rims
Zdroj: Geochimica et Cosmochimica Acta
Geochimica et Cosmochimica Acta, 2021, Geochimica et Cosmochimica Acta, 295, pp.135-154. ⟨10.1016/j.gca.2020.12.015⟩
Geochimica et Cosmochimica Acta, Elsevier, 2021, Geochimica et Cosmochimica Acta, 295, pp.135-154. ⟨10.1016/j.gca.2020.12.015⟩
ISSN: 0016-7037
DOI: 10.1016/j.gca.2020.12.015⟩
Popis: International audience; Fine-grained rims (FGRs) are ubiquitous in chondrites. They consist of unequilibrated mineral assemblages that surround chondrules and refractory inclusions. As such, they carry information about the material that was accreted onto chondrules. To decipher the nature and the formation mechanism of FGRs and compare them to adjacent matrix material, we investigated their composition, mineralogy, density and texture in the pristine Paris CM chondrite. We coupled a new method at the SEM scale (ACADEMY) that allows high-resolution quantitative petrology and an analytical TEM study.Significant differences in modal abundance, grain size and porosity are observed between the FGRs and their adjacent matrix. Amorphous silicates domains embedding nanosulfides are indicative of a high preservation degree. They are less abundant in the matrix than in the rims. In contrast, secondary alteration phases (phyllosilicates, carbonates and tochilinites) are more abundant in the matrix and associated with larger and fewer sulfides grains. The similar composition of the amorphous silicate in the rims and the matrix attests for a close relationship between the two reservoirs. However, matrix underwent more aqueous alteration. We interpret it as the result of the accretion of material with a higher water/rock ratio in the matrix, leading to a more aqueously altered microenvironment. We also find that coarse-grained anhydrous silicates (olivine and pyroxene) are present in the matrix but not in the FGRs, likely as a result of a chondrule fragmentation episode that occurred after FGR but before matrix accretion.Most of the time, FGRs display distinct inner and outer layers. The inner part is compact and displays larger sulfide grains than the outer part, which is more porous (porosity ∼ 45%) and altogether more pristine. These mineral and textural differences are not easily explained by differential aqueous alteration. Instead, a pre-accretion thermal process that preferentially affected the inner rim could have induced loss of porosity, compaction of the amorphous silicate domains as well as sulfides growth. We therefore suggest that FGRs acquired their characteristics in the nebula before matrix accretion and discuss possible mechanisms such as dust heating in the chondrule formation environment or secondary heating episode of the previously rimmed chondrule.
Databáze: OpenAIRE
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