Dolomites in hydrated fine-grained Antarctic micrometeorites: Effective tools for analyzing secondary processes - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Geochimica et Cosmochimica Acta Année : 2022

Dolomites in hydrated fine-grained Antarctic micrometeorites: Effective tools for analyzing secondary processes

E. Dobrică
  • Fonction : Auteur
K.K. Ohtaki
  • Fonction : Auteur

Résumé

We report detailed transmission electron microscope (TEM) observations of carbonates from one hydrated fine-grained Antarctic micrometeorite (H-FgMM). These carbonates show the occurrence of complex chemical variations and microstructures that provide important evidence regarding the formation and evolution of rarely analyzed H-FgMMs. The chemical variations were identified at both micrometer and nanometer scales, indicating that these carbonates formed under localized fluid conditions that suggest a variable chemical microenvironment. Individual carbonates grew from isolated reservoirs of fluid. Moreover, these carbonates contain manganese amounts almost twice as high as those measured in CM chondrites but similar to those identified in CI chondrites. Their particular compositions indicate reducing and progressively evolving conditions in the fluid from which these carbonates precipitated, probably due to water consumption during phyllosilicates formation. In addition to the compositional variability, microstructural features are pervasive in these carbonates, similar to those described in heavily shocked meteorites indicating that these carbonates were probably modified during shock processes after their formation. Since carbonates are highly susceptible to shock metamorphism, we suggest that it is essential to investigate their structure in detail before interpreting the isotopic measurements related to the time of their formation. Additionally, associated with carbonates, ubiquitous phosphates were identified in the micrometeorite analyzed. Future studies of these mineral associations will provide us further insight into the formation and evolution of asteroids, especially since they were both identified in the surface materials of Ryugu and Bennu.
Fichier principal
Vignette du fichier
Dobrica_2021_soumis.pdf (2.41 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-03572244 , version 1 (17-11-2022)

Identifiants

Citer

E. Dobrică, K.K. Ohtaki, C. Engrand. Dolomites in hydrated fine-grained Antarctic micrometeorites: Effective tools for analyzing secondary processes. Geochimica et Cosmochimica Acta, 2022, 317, pp.286-305. ⟨10.1016/j.gca.2021.11.018⟩. ⟨hal-03572244⟩
21 Consultations
26 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More