Possible fluid rock interactions on differentiated asteroids recorded in eucritic meteorites - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Geochimica et Cosmochimica Acta Année : 2011

Possible fluid rock interactions on differentiated asteroids recorded in eucritic meteorites

Résumé

The eucritic meteorites are basaltic rocks that originate from the upper part of the crust of some small bodies as exemplified possibly by asteroid 4-Vesta. A few eucrites appear to have been modified by different degrees of a late stage alteration process that caused significant variations in mineralogy. Three distinct alteration stages are identified: 1/ Fe-enrichment along the cracks that cross cut the pyroxene crystals ("Fe-metasomatism"); secondary olivine and minute amounts of troilite are found only occasionally in cracks at this stage; 2/ deposits of Fe-rich olivine (Fa64-86) and minor amounts of troilite are frequent inside the cracks; sporadic secondary Ca-rich plagioclase (An97-98) is associated with the fayalitic olivine; 3/ at this stage, the Fe-enrichment of the pyroxene is accompanied by a marked Al-depletion; moreover, secondary Ca-rich plagioclase is more frequent and partly fills some cracks or rims of the primary plagioclase crystals. The composition of the secondary phases on one hand, the lack of incompatible trace element enrichment in the metasomatized pyroxenes on the other hand, rule out a silicate melt as the metasomatic agent. Although no hydrous phase has been yet identified in the studied samples, aqueous fluids are plausible candidates for explaining the deposits of ferroan olivine and anorthitic plagioclase inside the fractures of the studied unequilibrated eucrites.
Fichier principal
Vignette du fichier
GCA_W7888_JA-Barrat.pdf (5.54 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

insu-00586415 , version 1 (15-04-2011)

Identifiants

  • HAL Id : insu-00586415 , version 1

Citer

Jean-Alix J-A Barrat, A. Yamaguchi, T.E. Bunch, Marcel Bohn, Claire Bollinger, et al.. Possible fluid rock interactions on differentiated asteroids recorded in eucritic meteorites. Geochimica et Cosmochimica Acta, 2011, 75 (13), pp.3839-3852. ⟨insu-00586415⟩
363 Consultations
415 Téléchargements

Partager

Gmail Facebook X LinkedIn More