The Meso-Cenozoic thermo-tectonic evolution of the Eastern Pyrenees: an Ar-40/Ar-39 fission track and (U-Th)/He thermochronological study of the Canigou and Mont-Louis massifs - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue International Journal of Earth Sciences Année : 2008

The Meso-Cenozoic thermo-tectonic evolution of the Eastern Pyrenees: an Ar-40/Ar-39 fission track and (U-Th)/He thermochronological study of the Canigou and Mont-Louis massifs

O. Maurel
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  • PersonId : 862827
Patrick Monie
R. Pik
Nicolas Arnaud
Maurice Brunel
  • Fonction : Auteur
  • PersonId : 862188
Marc Jolivet

Résumé

Vertical displacements on the SW-NE T (e) over capt fault (Eastern Pyrenees Axial Zone, France), which separates the Variscan Canigou-Caranca and Mont-Louis massifs, were constrained using a thermochronologic multi-method approach. Ar-40/Ar-39 data from the granitic Mont-Louis massif record its Variscan cooling history and reveal no ages younger than Early Cretaceous, while the Canigou-Caranca gneiss massif records systematically younger Ar-40/Ar-39 ages. These younger Ar-40/Ar-39 ages in the Canigou-Caranca gneiss massif are the result of partial to total rejuvenation of argon isotopic systems related to a thermal flow coeval with the Cretaceous HT-BP metamorphism in the North Pyrenean Zone. Only the deepest rocks from the Canigou-Caranca suffered this extensive Mid-Cretaceous thermal overprint probably due to differential burial around 4 km at that time. The post Mid-Cretaceous vertical displacements along the T (e) over capt fault are recorded by "low" temperature thermochronology using K-feldspar Ar-40/Ar-39, zircon and apatite fission track and (U-Th)/He datings. The Mont-Louis granite samples experienced a long period of protracted cooling reflecting a lack of thermo-tectonic activity in this area from Late Palaeozoic to Early Cenozoic, followed by cooling from 55-60 Ma to Late Eocene at a mean rate of 15-20 degrees C/Ma in the final stage. This cooling stage corresponds to T (e) over capt fault reactivation with a reversed component, promoting exhumation of the Mont-Louis roof zone contemporaneously with the south-vergent Pyrenean thrusting. In the Canigou-Caranca massif, the main cooling event occurred from 32 to 18 Ma at a maximum rate of 30 degrees C/Ma during Early Oligocene followed by a more moderate rate of 3 degrees C/Ma from Late Oligocene to Early Burdigalian, coeval with the normal reactivation of the T (e) over capt fault in brittle conditions that accommodated the final exhumation of the massif during the opening of the Gulf of Lion.

Dates et versions

hal-00411442 , version 1 (27-08-2009)

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Citer

O. Maurel, Patrick Monie, R. Pik, Nicolas Arnaud, Maurice Brunel, et al.. The Meso-Cenozoic thermo-tectonic evolution of the Eastern Pyrenees: an Ar-40/Ar-39 fission track and (U-Th)/He thermochronological study of the Canigou and Mont-Louis massifs. International Journal of Earth Sciences, 2008, 97 (3), pp.565-584. ⟨10.1007/s00531-007-0179-x⟩. ⟨hal-00411442⟩
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