Journal cover Journal topic
Solid Earth An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 4.165 IF 4.165
  • IF 5-year value: 4.075 IF 5-year
    4.075
  • CiteScore value: 4.28 CiteScore
    4.28
  • SNIP value: 1.501 SNIP 1.501
  • SJR value: 1.060 SJR 1.060
  • IPP value: 4.21 IPP 4.21
  • h5-index value: 29 h5-index 29
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 27 Scimago H
    index 27
Volume 6, issue 2
Solid Earth, 6, 643-668, 2015
https://doi.org/10.5194/se-6-643-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Solid Earth, 6, 643-668, 2015
https://doi.org/10.5194/se-6-643-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 08 Jun 2015

Research article | 08 Jun 2015

High-temperature metamorphism during extreme thinning of the continental crust: a reappraisal of the North Pyrenean passive paleomargin

C. Clerc1,2,*,**, A. Lahfid3, P. Monié2, Y. Lagabrielle4, C. Chopin1, M. Poujol4, P. Boulvais4, J.-C. Ringenbach5, E. Masini5, and M. de St Blanquat6 C. Clerc et al.
  • 1Laboratoire de Géologie, CNRS-UMR8538, Ecole normale supérieure, 24 rue Lhomond, 75231 Paris, France
  • 2Géosciences Montpellier, CNRS-UMR 5243, Université de Montpellier 2, Place Eugène Bataillon, 34095 Montpellier, France
  • 3BRGM/ISTO, 3 avenue Claude Guillemin, 45000 Orléans, France
  • 4Géosciences Rennes, UMR 6118, Université Rennes 1, Campus de Beaulieu, 35042 Rennes, France
  • 5TOTAL, CSTJF, avenue Larribau, 64000 Pau, France
  • 6GET, 14 avenue Edouard Belin, 31400 Toulouse, France
  • *now at: ISTO, 1A rue de la Férollerie, 45100 Orléans, France
  • **Invited contribution by C. Clerc, recipient of the EGU Outstanding Student Poster (OSP) Award 2012.

Abstract. An increasing number of field examples in mountain belts show that the formation of passive margins during extreme continent thinning may occur under conditions of high to very high thermal gradient beneath a thin cover of syn-rift sediments. Orogenic belts resulting from the tectonic inversion of distal margins and regions of exhumed continental mantle may exhibit high-temperature, low-pressure (HT-LP) metamorphism and coeval syn-extensional, ductile deformation. Recent studies have shown that the northern flank of the Pyrenean belt, especially the North Pyrenean Zone, is one of the best examples of such inverted hot, passive margin. In this study, we provide a map of HT-LP metamorphism based on a data set of more than 100 peak-temperature estimates obtained using Raman spectroscopy of the carbonaceous material (RSCM). This data set is completed by previous PT (pressure and temperature) estimates based on mineral assemblages, and new 40Ar–39Ar (amphibole, micas) and U–Pb (titanite) ages from metamorphic and magmatic rocks of the North Pyrenean Zone. The implications on the geological evolution of the Cretaceous Pyrenean paleomargins are discussed. Ages range mainly from 110 to 90 Ma, and no westward or eastward propagation of the metamorphism and magmatism can be clearly identified. In contrast, the new data reveal a progressive propagation of the thermal anomaly from the base to the surface of the continental crust. Focusing on the key localities of the Mauléon basin, Arguenos–Moncaup, Lherz, Boucheville and the Bas-Agly, we analyze the thermal conditions prevailing during the Cretaceous crustal thinning. The results are synthetized into a series of three regional thematic maps and into two detailed maps of the Arguenos–Moncaup and Lherz areas. The results indicate a first-order control of the thermal gradient by the intensity of crustal thinning. The highest grades of metamorphism are intimately associated with the areas where subcontinental mantle rocks have been unroofed or exhumed.

Publications Copernicus
Download
Short summary
The northern flank of the Pyrenean belt is an example of an inverted hot passive margin. We provide a data set of more than 100 peak-temperature estimates by RSCM and 18 new radiogenic ages from metamorphic and magmatic rocks from the North Pyrenean Zone. The results indicate a first-order control of the thermal gradient by the intensity of the Cretaceous crustal thinning. The highest grades of metamorphism are associated with the areas where mantle peridotites have been unroofed or exhumed.
The northern flank of the Pyrenean belt is an example of an inverted hot passive margin. We...
Citation
Share