Significado de las evaporitas del Carbonífero medio de la cuenca de antepaís Varisca (N de España y S de Francia)

  1. I. Díaz-García 1
  2. O. Merino-Tomé 1
  3. I.E. Quijada 1
  4. J.R. Bahamonde 1
  5. L.P. Fernández 1
  6. G. Della Porta 2
  7. E. Samankassou 3
  8. F. Ortí 4
  9. A.G. Borrego 5
  10. J. Martín-Llaneza 1
  11. M. Valenzuela 1
  1. 1 Universidad de Oviedo
    info

    Universidad de Oviedo

    Oviedo, España

    ROR https://ror.org/006gksa02

  2. 2 University of Milan
    info

    University of Milan

    Milán, Italia

    ROR https://ror.org/00wjc7c48

  3. 3 Université de Genève
    info

    Université de Genève

    Ginebra, Suiza

    ROR https://ror.org/01swzsf04

  4. 4 Universitat de Barcelona
    info

    Universitat de Barcelona

    Barcelona, España

    ROR https://ror.org/021018s57

  5. 5 Instituto de Ciencia y Tecnología del Carbono (INCAR-CSIC)
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Journal:
Geotemas (Madrid)

ISSN: 1576-5172

Year of publication: 2021

Issue Title: X Congreso Geológico de España

Issue: 18

Pages: 149

Type: Article

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More publications in: Geotemas (Madrid)

Abstract

During the Variscan Orogeny, the Gondwana-Laurentia collision led to the narrowing and closure of the Rheic Ocean. Under this scenario, a 60-400 m-thick pelagic succession of dark laminated calci-mudstones was accumulated over the distal realms of the Variscan foreland basin (Barcaliente Fm, Cantabrian Zone; Iraty Fm, Pyrenees) around the Mississippian-Pennsyl- vanian boundary. The upper part of this succession is characterized by the presence of an up to 20 m-thick stratal package with pseudomorphs after intrasediment gypsum, which become more abundant upwards even representing the 60% of the rock volume at the top. The common presence of radiolaria biomolds in this stratal package and the sedimentary structures suggest that evaporite deposition took place in an open subtidal marine environment, although the scarcity of benthic biota prevents further paleobathymetric interpretations. In such conditions, gypsum precipitation could have been related with a strong ocean stratification, with deep brines and shallow normal marine waters. Locally, subaerial exposure features are observed atop the evaporitic package, which record a significant relative sea-level fall that could be coincident with early Bashkirian eustatic lowstand recognised world-wide.

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