A two-stage collision at the origin of Pangeathe allochthonous Variscan terranes

  1. R. Arenas 1
  2. R. Díez Fernández 1
  3. S. Sánchez Martínez 1
  4. A. Gerdes 2
  5. J. Fernández-Suárez 1
  6. R. Albert 1
  7. J.M. Fuenlabrada 1
  1. 1 Universidad Complutense de Madrid
    info

    Universidad Complutense de Madrid

    Madrid, España

    ROR 02p0gd045

  2. 2 Institut für Geowissenschaften, Goethe University
Journal:
Geotemas (Madrid)

ISSN: 1576-5172

Year of publication: 2016

Issue Title: IX CONGRESO GEOLÓGICO DE ESPAÑA

Issue: 16

Pages: 175-178

Type: Article

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Abstract

The Variscan suture exposed in NW Iberia contains two allochthonous terranes with Gondwanan provenance (upper and basal units), separated by ophiolites with protolith ages at c. 395 Ma. The tectonothermal evolution of the continental terranes records two consecutive events of deep subduction. The upper units record an initial high-P/ultra-high-P metamorphic event that occurred before 400-390 Ma, while the basal units were affected by a second high-P/low-to-intermediate-T metamorphic event at c. 370 Ma. Repeated continental subduction affecting the most external margin of Gondwana occurred in a setting of dextral convergence with Laurussia. The two high-P events alternated with the opening of an ephemeral oceanic basin, probably of pull-apart type, in Early Devonian times. This ephemeral oceanic domain is suggested as the setting for the protoliths of the most common ophiolites involved in the Variscan Orogen. Current ideas for the assembly of Pangea advocate a single collisional event in Carboniferous times. However, the new evidence from the allochthonous terranes of the Variscan Orogen suggest a more complex scenario for the assembly of the supercontinent, with an interaction between the colliding continental margins that started earlier and lasted longer than previously considered.

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