U–Pb evidence for a polyorogenic evolution of the HP–HT units of the NW Iberian Massif

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dc.contributor.authorFernández Suárez, Javier
dc.contributor.authorCorfu, Fernando
dc.contributor.authorArenas Martín, Ricardo
dc.contributor.authorMarcos Vallaure, Alberto
dc.contributor.authorMartínez Catalán, José Ramón
dc.contributor.authorDíaz García, Florentino
dc.contributor.authorAbati Gómez, Jacobo
dc.contributor.authorFernández Rodríguez, Francisco José
dc.date.accessioned2023-06-20T17:05:42Z
dc.date.available2023-06-20T17:05:42Z
dc.date.issued2002
dc.description(The original publication is available at www.springerlink.com)
dc.description.abstractA isotope dilution thermal ionisation mass spectrometry U–Pb geochronological study was carried out on the high-pressure and high-temperature units (HP–HT units) overlyingthe oceanic suture in the Allochthonous Complexes of the NW Iberian Variscan Belt. The rocks investigated are seven granulite- to eclogitefacies paragneisses and one leucosome within mafic highpressure granulites in the Ordenes and Cabo Ortegal Complexes of NW Spain. U–Pb datingof zircon, monazite, titanite and rutile reveal the presence of a pervasive Early Ordovician metamorphic event at ca. 500–480Ma and a later Early Devonian event at ca. 400–380 Ma. The U–Pb ages, in conjunction with petrological and structural data, indicate that the high-pressure event recorded by these rocks is Early Ordovician in age. Monazite ages in the paragneisses suggest that peak metamorphic conditions were reached at ca. 500–485Ma. Subsequently, the rock ensemble underwent exhumation accompanied by partial meltingan d zircon growth at ca. 485–470Ma. Meltingof mafic granulites was coeval with this latter episode as indicated by zircon crystallisation age in the leucosomes dated at ca. 486 Ma. Based on these data and on the general features of magmatism and metamorphic evolution, it is proposed that this process took place at a convergent plate boundary within a peri-Gondwanan oceanic domain. Monazite, titanite and rutile data in some of the samples studied show evidence of a second metamorphic episode that took place between ca. 400 and 380 Ma (with a peak at ca. 390–385Ma). This Early Devonian event, at variance with the previous one, was not pervasive, but, rather, was localised in areas of intense Variscan tectonothermal reworking. It is claimed that this later metamorphic event was recorded by the U–Pb system in areas where monazite and titanite growth was enhanced by fluid circulation in highly strained rocks (Variscan shear zones). Accordingto previous structural studies and Ar–Ar datingof fabrics, this Early Devonian episode took place as the HP–HT units were deformed and thrusted upon the ophiolitic units in the early stages of the Variscan collision.
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/17429
dc.identifier.doiDOI 10.1007/s00410-001-0337-2
dc.identifier.issn0010-7999
dc.identifier.officialurlhttp://link.springer.com/journal/410
dc.identifier.urihttps://hdl.handle.net/20.500.14352/57760
dc.journal.titleContributions to mineralogy and petrology
dc.language.isoeng
dc.page.final253
dc.page.initial236
dc.publisherSpringer Science Business Media
dc.rights.accessRightsopen access
dc.subject.cdu550.93(234.1)
dc.subject.cdu551.24(234.1)
dc.subject.keywordU–Pb geochronological study
dc.subject.keywordNW Iberian
dc.subject.keywordVariscan Belt
dc.subject.ucmPetrología
dc.subject.ucmGeodinámica
dc.subject.unesco2507 Geofísica
dc.titleU–Pb evidence for a polyorogenic evolution of the HP–HT units of the NW Iberian Massif
dc.typejournal article
dc.volume.number143
dspace.entity.typePublication
relation.isAuthorOfPublicationa6e74377-1c86-4236-9e6a-72091bd7b56d
relation.isAuthorOfPublication590ee677-786b-4d34-b10b-30b65d1a8d35
relation.isAuthorOfPublication6cb07e41-d685-424f-9bd7-48e62c3dc87f
relation.isAuthorOfPublication.latestForDiscoverya6e74377-1c86-4236-9e6a-72091bd7b56d
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