Thermal interaction of middle and upper crust during gneiss dome formation: Example from the Montagne Noire (French Massif Central) - INSU - Institut national des sciences de l'Univers
Article Dans Une Revue Journal of Metamorphic Geology Année : 2016

Thermal interaction of middle and upper crust during gneiss dome formation: Example from the Montagne Noire (French Massif Central)

Résumé

This paper aims to decipher the thermal evolution of the Montagne Noire Axial Zone (MNAZ,southern French Massif Central) gneiss core and its metasedimentary cover through determination ofP–T paths and temperature gradients. Migmatitic gneiss from the core of the dome record a clock-wise evolution culminating at 725 25 °C and 0.8 0.1 GPa with partial melting, followed by adecompression path with only minor cooling to 690 25° C and 0.4 0.1 GPa. Field structuralanalyses as well as detailed petrological observations interpreted in a petrogenetic grid indicate thatthe cover sequence experienced LP-HT metamorphism at <0.4 GPa. Apparent thermal gradientswithin the cover were determined with garnet–biotite thermometry and Raman Spectroscopy on Car-bonaceous Matter. High-temperature apparent gradients (e.g. 530 °C km1 along one transect) areexplained by late brittle–ductile extensional shearing evidenced by phyllonites that post-date peakmetamorphism. In areas where normal faults are less abundant and closely spaced, gradients of 20to 50 °C km1 are calculated. These gradients can be accounted for by a combination of domeemplacement and ductile shearing (collapse of isotherms), without additional heat input. Finally, thethermal evolution of the MNAZ is typical for many gneiss domes worldwide as well as with otherLP-HT terranes in the Variscides.
Fichier principal
Vignette du fichier
jmg12188.pdf (2.15 Mo) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

insu-01290388 , version 1 (17-05-2016)

Licence

Identifiants

Citer

Kévin Fréville, Bénédicte Cenki-Tok, Pierre Trap, M. Rabin, A. Leyreloup, et al.. Thermal interaction of middle and upper crust during gneiss dome formation: Example from the Montagne Noire (French Massif Central). Journal of Metamorphic Geology, 2016, 34, pp.447-462. ⟨10.1111/jmg.12188⟩. ⟨insu-01290388⟩
333 Consultations
465 Téléchargements

Altmetric

Partager

More