A peri-Gondwanan arc in NW Iberia I: Isotopic and geochemical constraints on the origin of the arc—A sedimentary approach

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dc.contributor.authorFuenlabrada Pérez, José Manuel
dc.contributor.authorArenas Martín, Ricardo
dc.contributor.authorSánchez Martínez, Sonia
dc.contributor.authorDíaz García, Florentino
dc.contributor.authorCastiñeiras García, Pedro
dc.date.accessioned2023-06-20T00:07:23Z
dc.date.available2023-06-20T00:07:23Z
dc.date.issued2010
dc.description.abstractThe arc-derived upper terrane in the NW Iberia Variscan belt contains a 3000 m thick turbiditic formation at its structural top. Most of the sandstones are feldspathic greywackes with a framework of quartz and weakly altered plagioclase. Rock fragments of vitric and microgranular texture are common in polymictic conglomerates and coarse-grained greywackes, together with slates, cherts and bipyramidal volcanic quartz fragments. Although recrystallization under greenschists facies conditions (chlorite and biotite zones) and the presence of two cleavages hinder detailed textural analysis, the sandstones appear to be typically immature, first-cycle sandstones. The metagreywackes have average major and trace element compositions similar to PAAS (Post Archean Australian Shale), which is considered to reflect the composition of the upper continental crust. Their trace element composition is very consistent and records deposition within a convergent tectonic setting, probably in an intra-arc basin located in a volcanic arc built on thinned continental margin. Detrital zircon populations suggest a Middle Cambrian maximum depositional age (530–500 Ma) and a Gondwanan provenance located at the periphery of the West African Craton. Nd isotope data suggest mixing Ediacaran and Paleoproterozoic sources for the provenance of the greywackes, with TDM ranging between 720 and 1215 Ma with an average of 995 Ma (n=20)—an age range unrepresented in the detrital zircon population. The Nd model ages are similar to those exhibited by West Avalonia, Florida or the Carolina terrane, but younger than those of Cambrian and Ordovician sandstones and shales from the autochthonous realm. These data suggest a westernmost location along the Gondwanan margin for the upper terrane of NW Iberia relative to other terranes located in the footwall of the Variscan suture, consistent with several previously proposed paleogeographic models for the NW Iberia terranes.
dc.description.departmentDepto. de Mineralogía y Petrología
dc.description.facultyFac. de Ciencias Geológicas
dc.description.refereedTRUE
dc.description.statuspub
dc.eprint.idhttps://eprints.ucm.es/id/eprint/14027
dc.identifier.doi10.1016/j.gr.2009.09.007
dc.identifier.issn1342-937X
dc.identifier.officialurlhttp://www.elsevier.com/locate/gr
dc.identifier.urihttps://hdl.handle.net/20.500.14352/42022
dc.journal.titleGondwana research
dc.language.isoeng
dc.page.final351
dc.page.initial338
dc.publisherElsevier Science B. V., Amsterdam
dc.rights.accessRightsopen access
dc.subject.cdu552.3
dc.subject.keywordCambrian turbidites
dc.subject.keywordSediment geochemistry
dc.subject.keywordNd isotope composition
dc.subject.keywordProvenance
dc.subject.keywordPeri-Gondwanan arc
dc.subject.keywordAllochthonous complexes
dc.subject.keywordNW Iberia
dc.subject.ucmPetrología
dc.titleA peri-Gondwanan arc in NW Iberia I: Isotopic and geochemical constraints on the origin of the arc—A sedimentary approach
dc.typejournal article
dc.volume.number17
dspace.entity.typePublication
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