Garnet-chloritoid-kyanite metapelites from the Raspas Complex (SW Ecuador): a key eclogite-facies assemblage

Détails

ID Serval
serval:BIB_51D2A12808FF
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Garnet-chloritoid-kyanite metapelites from the Raspas Complex (SW Ecuador): a key eclogite-facies assemblage
Périodique
European Journal of Mineralogy
Auteur(s)
Gabriele P., Ballevre M., Jaillard E., Hernandez J.
ISSN-L
0935-1221
Statut éditorial
Publié
Date de publication
2003
Peer-reviewed
Oui
Volume
15
Pages
977-989
Langue
anglais
Notes
ISI:000187612500005
Résumé
The Raspas Complex (Ecuador) contains one of the few eclogitic bodies in
the northern Andes. It consists of metaperidotites, eclogites, and
metapelites. The latter display three assemblages: (i) garnet +
chloritoid + kyanite, (ii) garnet + chloritoid and (iii) garnet +
chlorite, in all cases with quartz and muscovite in addition. The growth
of these assemblages was coeval with the main ductile deformation, and
was followed by minor reequilibration (chlorite growth in garnet +
chloritoid samples and chloritoid + quartz aggregates replacing garnet
and kyanite in garnet + chloritoid + kyanite samples). Detailed
microprobe analyses show increasing magnesian compositions for garnet
(from core to rim) and chloritoid (inclusions within garnet compared to
matrix grains) in kyanite-bearing samples. The above data are
interpreted in the framework of the KFMASH system. Reaction progress
along the divariant reaction Cld = Grt + Ky explains the change in
chemistry of coexisting phases. The divariant Grt-Cld-Ky assemblage has
a narrow stability field, and the P-T conditions are estimated at about
20 kbar, 550-600degreesC. Decompression, recorded by chloritoid-quartz
pseudomorphs of garnet, probably occurred as temperature decreased.
Création de la notice
11/12/2012 16:25
Dernière modification de la notice
03/03/2018 17:11
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