Age of metamorphism and deformation in the Montagne Noire dome (French Massif Central): Tapping into the memory of fine-grained gneisses using monazite U-Th-Pb geochronology

Françoise Roger, Christian Teyssier, Donna L. Whitney, Jean Patrick Respaut, Jean Louis Paquette, Patrice F. Rey

Research output: Contribution to journalArticle

Abstract

Recent work has revealed that the Montagne Noire dome, located in the foreland of the Variscan belt (French Massif Central), contains a record of nearly coeval, late Variscan eclogitization and migmatization. Given these new results, it is important to understand the chronology of events that produced high-grade metamorphism and exhumation. Using U-Th-Pb dating of monazite, this study confirms ages of ~315–300 Ma for high-T metamorphism in the augen gneiss that makes up a large fraction of the Montagne Noire dome, and documents for the first time ~295 Ma monazite ages in compositionally varied fine-grained gneisses that form folded continuous layers within the core of the dome. The fine-grained gneiss layers are intensely sheared and are interpreted to have localized late, high-T deformation in the core of the dome. These sheared fine-grained gneisses form a network of shear zones that were kinematically linked to the extensional and strike-slip deformation zones that exhumed the Montagne Noire dome in a pull-apart (s.l.) domain. Continued deformation-recrystallization and fluid flow within these shear zones likely drove rejuvenation of monazite for ~5 million years after much of the melt had crystallized in the Montagne Noire dome.

Original languageEnglish (US)
Article number228316
JournalTectonophysics
Volume776
DOIs
StatePublished - Feb 5 2020

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geochronology
monazite
domes
dome
metamorphism
gneiss
Hercynian orogeny
shear zone
augen gneiss
shear
migmatization
chronology
dating
exhumation
fluid flow
grade
slip
melt

Keywords

  • Exhumation of partially molten crust
  • Fine grained gneisses
  • High-T deformation
  • Migmatite dome
  • Monazite U-Th-Pb dating
  • Montagne Noire, France

Cite this

Age of metamorphism and deformation in the Montagne Noire dome (French Massif Central) : Tapping into the memory of fine-grained gneisses using monazite U-Th-Pb geochronology. / Roger, Françoise; Teyssier, Christian; Whitney, Donna L.; Respaut, Jean Patrick; Paquette, Jean Louis; Rey, Patrice F.

In: Tectonophysics, Vol. 776, 228316, 05.02.2020.

Research output: Contribution to journalArticle

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