High-pressure metamorphism of the Lanzo peridotite and its oceanic cover, and some consequences for the Sesia-Lanzo zone (northwestern Italian Alps)

Détails

ID Serval
serval:BIB_38DD10D2164C
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
High-pressure metamorphism of the Lanzo peridotite and its oceanic cover, and some consequences for the Sesia-Lanzo zone (northwestern Italian Alps)
Périodique
Lithos
Auteur(s)
Pelletier L., Muntener O.
ISSN-L
0024-4937
Statut éditorial
Publié
Date de publication
2006
Peer-reviewed
Oui
Volume
90
Pages
111-130
Langue
anglais
Résumé
This paper presents new data on the Alpine high-pressure evolution of
the Lanzo peridotite massif and its metasedimentary cover (Western
Alps). Field relations in the northwestern Lanzo massif show that the
serpentinized part is covered by a metasedimentary sequence including
local occurrences of metaophicarbonate, metabasalt, calcschist,
metaquartzite and gneiss. Remnants of granulite-facies mafic gneiss
associated with metaophicarbonate are found within the serpentinite.
Major element garnet zonation profiles in metaquartzite and mafic
gneiss were used to explore the contrasting origin of metasediments.
Bell-shaped Mn zoning in garnet from metaquartzite indicates a
one-stage Alpine metamorphic evolution, while inverse zoning in garnet
of the mafic gneiss shows that the protolith equilibrated under
high-grade metamorphic conditions in pre-Alpine times, similar to
kinzigites within the neighbouring Sesia zone. Phase equilibria in
metaquartzite and mafic gneiss point to 500 +/- 50 degrees C at
pressures of 0.9 to 1.3GPa for the Alpine metamorphic equilibration
that contrasts with the 550-620 degrees C and pressures in excess of
2.0GPa obtained for kyanite+talc+chloritoid and talc+chloritoid+garnet
domains in a metagabbro dike from the internal part of the Lanzo
massif. These different P-T trajectories can be explained by a much
stronger retrograde overprint at the basement-cover contact than in the
internal part of the Lanzo massif. (c) 2006 Elsevier B.V. All rights
reserved.
Création de la notice
18/04/2009 0:56
Dernière modification de la notice
20/08/2019 14:28
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