Service interruption on Monday 11 July from 12:30 to 13:00: all the sites of the CCSD (HAL, EpiSciences, SciencesConf, AureHAL) will be inaccessible (network hardware connection).
Skip to Main content Skip to Navigation
Journal articles

Polyphase post-Variscan thinning of the North Pyrenean crust: Constraints from the P-T-t-deformation history of the exhumed Variscan lower crust (Saleix Massif, France)

Abstract : As part of the Variscan orogen, the Pyrenean realm has undergone several rifting episodes, starting from the Permian-Carboniferous post-orogenic collapse and culminating with mid-Cretaceous lithospheric mantle exhumation. We present the Pressure-Temperature-time-deformation (P-T-t-d) evolution of the tonalite bodies (here described for the first time) intruded in the late Carboniferous high pressure (HP) granulites of the Saleix Complex, forming the inner envelope of the Lherz peridotites (Aulus Basin, Ariège, France), that is used as a proxy to reconstruct the post-Hercynian evolution of the Pyrenean continental crust. By integrating textural investigations with metamorphic thermobarometry, and zircon and titanite Usingle bondPb geochronology, we (i) constrain timing and thermo-baric conditions related to the transition from magma emplacement to solid-state syn-tectonic deformation in tonalite(s); and (ii) discuss implications on the polyphase exhumation history of the granulite host rocks. Emplacement of the Saleix tonalite(s) took place in the early Permian (ca. 281 Ma), in a thermo-baric environment (P = 0.5 ± 0.1 GPa and T = 750–880 ± 20 °C) attesting for an important thinning of the Pyrenean crust at the end of the Variscan cycle. Solid-state deformation occurred during the mid-Cretaceous (ca. 96 Ma), at shallow crustal depths (≤10 km) and under amphibolite facies metamorphic conditions. These results document that rifting events had already thinned the Pyrenean crust prior to the Cretaceous mantle exhumation and that the lower crust was affected by ductile deformation during the Cretaceous rifting. Our study demonstrates that in the Pyrenean realm the Permian crustal thinning played a very important role and that mantle exhumation resulted from polyphase post-Variscan, Permian-to-Cretaceous crustal thinning episodes.
Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03405053
Contributor : Isabelle Dubigeon Connect in order to contact the contributor
Submitted on : Wednesday, October 27, 2021 - 8:18:08 AM
Last modification on : Thursday, June 2, 2022 - 2:48:17 PM
Long-term archiving on: : Friday, January 28, 2022 - 6:18:52 PM

File

asti-2021.pdf
Files produced by the author(s)

Identifiers

Citation

Riccardo Asti, Federico Rossetti, Federico Lucci, Marc Poujol, yves Lagabrielle. Polyphase post-Variscan thinning of the North Pyrenean crust: Constraints from the P-T-t-deformation history of the exhumed Variscan lower crust (Saleix Massif, France). Tectonophysics, Elsevier, 2021, 820, pp.229122. ⟨10.1016/j.tecto.2021.229122⟩. ⟨insu-03405053⟩

Share

Metrics

Record views

61

Files downloads

31