Late Cambrian magmatic arc activity in peri-Gondwana : geochemical evidence from metagranitoid rocks of the Basal Allochthonous Units of NW Iberia
Andonaegui Moreno, Pilar (Universidad Complutense de Madrid. Departamento de Petrología y Geoquímica)
Abati Gómez, Jacobo (Universidad Complutense de Madrid. Departamento de Petrología y Geoquímica)
Diez Fernández, Rubén (Universidad Complutense de Madrid. Departamento de Geodinámica, Estratigrafía y Paleontología)

Fecha:	2017
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 llochthonous 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.
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Convergent margin ; Subduction ; Magmatism ; Whole rock geochemistry ; NW Iberian Massif
Publicado en:	Geologica acta, Vol. 15 Núm. 4 (December 2017) , p. 305-321, ISSN 1696-5728

Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2017.15.4.4
DOI: 10.1344/GeologicaActa2017.15.4.4

17 p, 2.9 MB

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