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Communication Dans Un Congrès Année : 2023

Partial melting triggered by differential kinetics of prograde reactions in eclogites: a process for transient weakening

Loic Labrousse
Marie Baïsset
Erwan Bras
  • Fonction : Auteur
  • PersonId : 1262265
Alexandre Schubnel
Julien Gasc
  • Fonction : Auteur
  • PersonId : 922508

Résumé

Partial melting along retrograde pressure-temperature path of the continental crust at (Ultra) High Pressure conditions has been acknowledged as a weakening mechanism responsible for the decoupling and subsequent exhumation of large scale (U)HP units in collision zones. At the shear zone scale, additional transient weakening mechanisms have to be considered, when exploring the development of eclogite-facies shear zones at peak conditions. Fluid flux, grain-size reduction, weak phase connectivity, have been for instance explored in this prospect. Here we present new petrological evidence from the Holsnøy Caledonian eclogite-facies overprint in hydrating granulites that transient weakening may also occur due to partial melting during prograde reactions. Post-melting analcime-kyanite-bearing textures appear at grain boundaries as a result of the reaction kinetics contrast between the Na and Ca end-members of the plagioclase solid solution during prograde hydration. Partial melting could therefore be an additional transient weakening mechanism occurring early during the eclogitization process of the continental crust.  

Domaines

Tectonique
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Dates et versions

insu-04441560 , version 1 (06-02-2024)

Identifiants

  • HAL Id : insu-04441560 , version 1

Citer

Loic Labrousse, Marie Baïsset, Erwan Bras, Alexandre Schubnel, Philippe Yamato, et al.. Partial melting triggered by differential kinetics of prograde reactions in eclogites: a process for transient weakening. RST 2023 - 28e Réunion des Sciences de la Terre, Société géologique de France (SGF), Oct 2023, Rennes, France. ⟨insu-04441560⟩
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