Éclogite du Lac Cornu

Retour à socle polycyclique anté-varisque du massif des Aiguilles Rouges

Représentation et statut

Couleur CMYK
(49%,0%,37%,31%)
Couleur RGB
R: 90 G: 175 B: 110
Rang
Formation lithostratigraphique
Usage
Ce terme est en usage.
Status
terme informel

Nomenclature

Deutsch
Lac-Cornu-Eklogit
Français
Éclogite du Lac Cornu
Italiano
Eclogite del Lac Cornu
English
Lac Cornu Eclogite
Origine du nom

Lac Cornu (France)

Variantes historiques

éclogites des Aiguilles Rouges (Joukowsky 1902), Lac Cornu retrograded eclogites (Liégeois & Duchesne 1981), --- (Paquette et al. 1989), masse-relique d'éclogites du lac Cornu (Pairis et al. 1992), mafic éclogites of Lac Cornu (Pfeifer & von Raumer 1996), éclogites du lac Cornu (Drouet & Leloup 2015)

Description

Description

14 kbar, min. 700°C (Schulz & von Raumer 1993)

Âge

Âge au sommet
  • Ordovicien tardif
Âge à la base
  • Ordovicien moyen
Méthode de datation

453 +3/-2 Ma (Paquette et al. 1989), 458 +/-5 Ma (Bussy et al. 2011), 463 +/-3 Ma (Bussy et al. 2011 ; protolithe éclogite rubannée)

Références

Révision
Bussy François, von Raumer Jürgen, Capuzzo Nicola (2001) : Mont-Blanc, Aiguilles-Rouges massifs (External Massifs) - an example of polyorogenic evolution. Fieldtrip Guide 1, 53-84, Univ. Lausanne

p. 65: (Retro-)eclogitized pyroxenites, lherzolites and N-MORB-type basalts are outcropping in the Lake Cornu area (Aiguilles Rouges). Paquette et al. (1989) interpreted an upper intercept U-Pb zircon age of 453 +2/-3 Ma as a magmatic crystallization age. These rocks were derived from a depleted mantle source (initial ε Nd = +6). They have been originally thought to be emplaced in a thinned continental crust associated with the initial stages of oceanic rifting (Paquette et al., 1989) and more recently to be emplaced in a back-arc setting associated with an active continental margin (Dobmeier et al., 1999). The latter interpretation is supported by the contemporaneous intrusion of several granites of calc-alkaline (Itype) or peraluminous (S-type) character, as expected in an active continental (or island-arc) margin.

Principales publications
Liégeois Jean-Paul, Duchesne Jean-Clair (1981) : The Lac Cornu retrograded eclogites (Aiguilles Rouges massif, Western Alps France): evidence of crustal origin and metasomafic alteration. Lithos 14, 35-48
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