Foliation and magnetic fabrics associated with fold interference in the Pyrenean Axial Zone (La Seu d’Urgell, Lleida)

Authors

  • Ana Simón Muzás Departamento de Ciencias de la Tierra, Geotransfer-IUCA, Universidad de Zaragoza
  • Antonio Casas Sainz Departamento de Ciencias de la Tierra, Geotransfer-IUCA, Universidad de Zaragoza
  • Ruth Soto Instituto Geológico y Minero de España (IGME), CSIC, Unidad de Zaragoza
  • Pilar Clariana Instituto Geológico y Minero de España (IGME), CSIC, Unidad de Zaragoza
  • Aina Margalef Andorra Recerca + Innovació, Sant Julià de Lòria, Principat d’Andorra

DOI:

https://doi.org/10.55407/geogaceta100813

Keywords:

fold interference, Sardic unconformity, cleavage, AMS, Variscan, Pyrenees

Abstract

The study area, in the vicinity of La Seu d’Urgell (Pyrenean Axial Zone), is composed of a stratigraphic series of Cambro-Ordovician rocks, mostly detrital, where the Sardic unconformity can be clearly identified, between the Jujols Series and Rabassa conglomerates Formation. The main structures are N-S folds with horizontal axial surfaces, that show an associated cleavage, well developed in the pelitic levels (and clearly distinguished in thin sections) and more poorly developed in the sandstone levels. In the conglomerates overlying the Sardic unconformity (Rabassa conglomerates Fm.) the regional cleavage is characterized by superposed conjugate shear bands surrounding the clasts. Magnetic fabrics (mainly paramagnetic) are consistent with the observed microstructures,although the correspondence of axes between the magnetic fabric and the structures observed in the field is not straightforward. The orientation of lineation directions are bimodal (N-S and E-W), a fact that can be interpreted as the result of fold interference (type 2 of Ramsay).

References

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Topografía del detal del cráter Gusev (Marte)

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Published

2024-06-29

How to Cite

Simón Muzás, A., Casas Sainz, A., Soto, R., Clariana, P., & Margalef, A. (2024). Foliation and magnetic fabrics associated with fold interference in the Pyrenean Axial Zone (La Seu d’Urgell, Lleida). GEOGACETA, 75, 35–38. https://doi.org/10.55407/geogaceta100813

Issue

Vol. 75 (2024): January-June

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Artículos

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Copyright (c) 2024 Ana Simón Muzás, Antonio Casas Sainz, Ruth Soto, Pilar Clariana, Aina Margalef

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