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Article Dans Une Revue Geology Année : 2019

Reaction-induced embrittlement of the lower continental crust

Sarah Incel
  • Fonction : Auteur
Loïc Labrousse
  • Fonction : Auteur
Timm John
  • Fonction : Auteur
Julien Gasc
  • Fonction : Auteur
Feng Shi
  • Fonction : Auteur
Yanbin Wang
  • Fonction : Auteur
  • PersonId : 867000
Torgeir B. Andersen
  • Fonction : Auteur
François Renard
  • Fonction : Auteur
Bjørn Jamtveit
  • Fonction : Auteur
Alexandre Schubnel
  • Fonction : Auteur

Résumé

Field observations and geophysical data reveal a causal link between brittle seismic failure and eclogitization of the lower continental crust. We present results from experimental deformation of plagioclase-rich samples at eclogite-facies conditions and quantify the link between rock rheology and the kinetics of the eclogitization reactions. The deformation was ductile both in the absence of reaction and when the progress of eclogitization was fast compared to the imposed strain rate. However, when the reaction rate was relatively slow, the breakdown of plagioclase into nanocrystalline reaction products triggered embrittlement, highlighted by a high acoustic emission activity. Fluid-induced plagioclase breakdown under eclogite-facies conditions is an exothermic reaction accompanied by a negative change in solid volume. This is similar to other mineral transformations that are known to trigger transformational faulting. We demonstrate that mineral reactions lead to brittle deformation in situations where reaction rates are slow compared to the deformation rate.

Dates et versions

hal-02183312 , version 1 (15-07-2019)

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Sarah Incel, Loïc Labrousse, Nadege Hilairet, Timm John, Julien Gasc, et al.. Reaction-induced embrittlement of the lower continental crust. Geology, 2019, Geology, 47 (3), pp.235-238. ⟨10.1130/G45527.1⟩. ⟨hal-02183312⟩
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