Late Cambrian magmatic arc activity in peri-Gondwanageochemical evidence from metagranitoid rocks of the Basal Allochthonous Units of NW Iberia.

  1. Andonaegui, P.
  2. Abati, J.
  3. Díez-Fernández, R.
Revista:
Geologica acta: an international earth science journal

ISSN: 1695-6133

Año de publicación: 2017

Título del ejemplar: . Special Issue: Granites and Related Rocks: a tribute to Guillermo Corretgé

Volumen: 15

Número: 4

Páginas: 305-321

Tipo: Artículo

DOI: 10.1344/GEOLOGICAACTA2017.15.4.4 DIALNET GOOGLE SCHOLAR lock_openAcceso abierto editor

Otras publicaciones en: Geologica acta: an international earth science journal

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Resumen

The North African section of the Gondwana margin was the site of voluminous, arc-related magmatism during the Late Neoproterozoic (Avalonian–Cadomian orogen). The lower (and older) metasedimentary sequence that constitutes the Basal Units of the Allochthonous Complexes of NW Iberia was deposited in that setting. In these units, sedimentation was followed by the intrusion of tonalites and granodiorites in the late Cambrian (ca. 493–489Ma). In the Late Paleozoic, the collision of Gondwana and Laurussia (Variscan orogeny) deformed and metamorphosed the whole ensemble.New whole rock geochemical analysis performed in seven samples of metatonalites and fourteen samples of metagranodiorites are characterized by: i) slight enrichment in incompatible elements (Rb, Ba, Th, U), ii) negative anomalies in Nb, Ta, P, and Ti, and iii) negative anomalies in Eu. These chemical features are in agreement with a subduction-related setting for the genesis of both types of magma, which is also supported by chemical discrimination using tectonic setting diagrams. Positive anomalies of Pb suggest a crustal component. The new geochemical data reveal that the convergent orogen that ruled the paleogeography of the Gondwana periphery during the Neoproterozoic (Cadomian orogen) remained active beyond the Neoproterozoic-Cambrian transition, up to at least late Cambrian times.

Información de financiación

This work has been funded the Ministerio de Economía y Competitividad through research grant CGL2016-76438-P. We thank Icaro Dias da Silva, Ricardo Arenas and an anonymous referee for detailed and constructive reviews which did much improve the manuscript.

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