U-Pb dating of Ordovician felsic volcanism in the Schistose Domain of the Galicia-Trás-os-Montes Zone near Cabo Ortegal (NW Spain)
DOI:
https://doi.org/10.1344/105.000001412Keywords:
Iberian Massif, Schistose Domain, U-Pb dating, OrdovicianAbstract
The northern termination of the Schistose Domain of the Galicia-Trás-os-Montes Zone is a tectonic slice named the Rio Baio Thrust Sheet, which is sandwiched between the Cabo Ortegal Complex and the Ollo de Sapo Domain of the Central-Iberian Zone. The Rio Baio Thrust Sheet is formed by two volcanosedimentary series, the Loiba and the Queiroga Series. The Loiba Series contains calc-alkaline dacite and rhyolite, while the overlying Queiroga Series has alkaline rhyolite. These series were considered to be in stratigraphically upwards continuity and believed to be Silurian in age. U-Pb dating of an alkaline rhyolite in the Queiroga Series provides an Arenig age of 475 ± 2 Ma. This age makes the Queiroga Series the oldest known stratigraphic unit in the Schistose Domain of the Galicia-Trás-os-Montes Zone, impeding correlation between the lithostratigraphic sequences of Ortegal and Central Galicia. As well as providing evidence of an unforeseen structural complexity within the Rio Baio Sheet, the new data supports the notion that the Schistose Domain is not parautochtonous, but a separate lithotectonic unit in thrust contact with the underlying Central-Iberian Zone.
References
Ancoechea, E., Arenas, R., Brandle, J.L., Peinado, M., Sagredo, J., 1988. Caracterización de las rocas metavolcánicas silúricas
del Noroeste del Macizo Ibérico. Geociências, 1-2, 23-34.
Arce Duarte, J.M., Fernández Tomás, J., 1976. Mapa Geológico de España. Scale 1:50.000, Hoja 8 (7-3), Vivero. Madrid, Instituto Geológico Minero España, 45 pp, 1 fold. map. Arce Duarte, J.M., Fernández Tomás, J., Monteserín López, V., 1977. Mapa Geológico de España. Scale 1:50.000, Hoja 7 (7-2), Cillero. Madrid, Instituto Geológico Minero España, 47 pp., 1 fold. map.
Arenas, R., 1984. Características y significado del volcanismo ordovícico-silúrico de la serie autóctona envolvente del Macizo de Cabo Ortegal (Galicia, NW España). Revista Materiales Procesos Geológicos, 11, 135-144.
Arenas, R., 1988. Evolución petrológica y geoquímica de la Unidad alóctona inferior del Complejo metamórfico básico
ultrabásico de Cabo Ortegal (Unidad de Moeche) y del Silúrico paraautóctono, Cadena Herciniana Ibérica (NW de España). Corpus Geologicum Gallaeciae, 4, 545 pp.
Bastida, F., Marcos, A., Marquínez, J., Martínez Catalán, J.R., Pérez-Estaún, A., Pulgar, J.A., 1984. Mapa Geológico de España. Scale 1:200.000, Hoja 1 (2-1), La Coruña. Madrid, Instituto Geológico Minero España, 155 pp, 1 fold. map.
Bastida, F., Aller, J., Fernández Viejo, G., 1993. The structure of the Ollo de Sapo antiform in the Cantabrian coast (NW Spain). Revista Sociedad Geológica España, 6, 93-103.
Díez Balda, M.A., Vegas, R., González Lodeiro, F., 1990. Structure (Central Iberian Zone). In: Dallmeyer, R.D., Martínez García, E. (eds.). Pre-Mesozoic Geology of Iberia. Berlin Heidelberg, ed. Springer-Verlag, 172-188 pp.
Evensen, M.M., Hamilton, P.J., O’nions, R.K., 1978. Rare-earth abundances in chondritic meteorites. Geochimica et Cosmochimica Acta, 42, 1199-1212.
Farias, P., 1987. La estructura herciniana del sector oriental del Sinclinal de Verín: Los cabalgamientos de Verín y Pradocabalos. Cuadernos Laboratorio Xeolóxico Laxe, 11, 295-303.
Farias, P., 1990. La geología de la Región del Sinforme de Verín (Cordillera Herciniana, NW de España). La Coruña, Edicións do Castro, Serie Nova Terra, 1-201.
Farias, P., Gallastegui, G., González-Lodeiro, F. , Marquínez, J., Martín Parra, L. , Martínez Catalán, J.R., De Pablo Maciá, J.G., Rodríguez Fernández, L.R., 1987. Aportaciones al conocimiento de la litoestratigrafía y estructura de Galicia Central. Faculdade de Ciências do Porto, Memorias do Museu e Laboratório Mineralógico e Geológico, 1, 411-431.
Farias, P., Marcos, A., 2004. Dominio Esquistoso de GaliciasTras-os-Montes. In: Vera, J.A. (ed.). Geología de España. Madrid, SGE-IGME, 135-138.
Fernández Pompa, F., Piera Rodríguez, T., 1975. Mapa Geológico de España. Scale 1:50.000, Hoja 22 (6-4), Puentedeume.
Madrid, Instituto Geológico Minero España, 45 pp, 1 fold. map.
Fernández Pompa, F., Monteserín López, V., 1976. Mapa Geológico de España. Scale 1:50.000, Hoja 7 (6-3), Cedeira. Madrid, Instituto Geológico Minero España, 73 pp, 1 fold. map.
Fernández-Suárez, J., Gutiérrez-Alonso, G., Jenner, G., Tubrett, M.N., 1999. Crustal sources in Lower Palaezoic rocks from
NW Iberia, insights from laser ablation U-Pb ages of detrital zircons. London, Journal of the Geological Society, 156, 1065-1068.
Ferragne, A., 1972. Le Précambrien et le Paléozoique de la Province de l’Orense (Nord-Ouest de l’Espagne). Stratigraphie-Tectonique-Métamorphisme. Doctoral thesis. Université de Bordeaux. Bordeaux, 249 pp.
Gebauer, D., Martínez García, E., Hepburn, J.C., 1993. Geodynamic significance, age and origin of the Ollo de Sapo Augengneiss (NW Iberian Massif, Spain). Annual meeting of Geological society of America, Boston, Abstracts with Programs, A-342.
Iglesias, M., Robardet, M., 1980. Silúrico de Galicia MediaCentral. Su importancia en la paleogeografía Varisca. Cuadernos Laboratorio Xeolóxico Laxe, 1, 99-115.
Jaffey, A.H., Flynn, K.F., Glendenin, L.E., Bentley, W.C., Essling, A.M., 1971. Precision measurement of the halflives and specific activities of 235U and 238U. Physics Review Section C, Nuclear Physics, 4, 1889-1906.
Krogh, T.E., 1973. A low-contamination method for the hydrothermal decomposition of zircon and the extraction of U and Pb for isotopic determinations. Geochimica et Cosmochimica Acta, 37, 485-494.
Krogh, T.E., 1982. Improved accuracy of U-Pb zircon ages by the creation of more concordant systems using an air abrasion
technique. Geochimica et Cosmochimica Acta, 46, 637-649.
Loveridge, W.D., 1986. Measurement of biases in the electron multiplier ion detection system of a Finnigan-MAT model 261 mass spectrometer. International Journal of Mass Spectrometry and Ion Processes, 74, 197-206.
Ludwig, K.R., 1991. PBDAT version 1.23
Ludwig, K.R.,1999. ISOPLOT/Ex. version 2.00.
Marcos, A., Farias, P., 1997. La estructura de la sutura varisca en la transversal de Cabo Ortegal (NW de España). In: Pires, C.C., Gomes, M.E.P., Coke, C. (eds.). Evoluçao geologica do Maciço Ibérico e seu enquadramento continental. 14 Reuniáo de Geologia do Oeste Peninsular, VilaReal, Portugal, Comunicaçoes, 109-114.
Marcos, A., Farias, P., 1999. La estructura de las láminas inferiores del Complejo de Cabo Ortegal y su autóctono relativo (Galicia, NO de España). Universidad de Oviedo, Trabajos de Geología, 21, 201-218.
Marcos, A., Farias, P., Galán, G., Fernández , F.J., Llana-Fúnez, S., 2002, The tectonic framework of the Cabo Ortegal Complex: a slab of lower crust exhumed in the Variscan Orogen (NW Iberian Peninsula). In: Martínez Catalán, J.R., Hatcher
Jr., R.D., Arenas, R., Díaz García, F. (eds.). VariscanAppalachian dynamics: The building of the late Paleozoic basement. Boulder, Colorado, Geological Society of America, Special Paper 364, 143-162.
Marcos, A., Llana Fúnez, S., 2002. Estratigrafía y estructura de la lámina tectónica del Para-autóctono y de su autóctono en
el área de Chantada (Galicia, NO de España). Universidad de Oviedo, Trabajos de Geología, 23, 53-72.
Marquínez, J.L., 1984. La geología del Area Esquistosa de Galicia Central (Cordillera Herciniana, NW de España). Instituto Geológico Minero España, Memorias, 100, 1-231.
Martínez Catalán, J.R., Arenas, R., Díaz García, F., Rubio Pascual, F.J., Abati, J., Marquínez, J., 1996. Variscan exhumation of a subducted Paleozoic continental margin: The basal units of the Ordenes Complex, Galicia, NW Spain. Tectonics, 15, 106-121.
Martínez Catalán, J.R., Arenas, R., Díaz García, F., Abati, J., 1997. Variscan accretionary complex of northwest Iberia: Terrane correlation and succession of tectonothermal events. Geology, 25, 1103-1106.
Martínez Catalán, J.R., Arenas, R., Díaz García, F., Abati, J., 1999. Allochthonous units in the Variscan Belt of NW Iberia (Terranes and Accrecionary History). In: Sinha, A.K. (ed.). Basement Tectonics 13. Kluwer Academic Publishers, 65-84.
Matte, Ph., 1968. La structure de la virgation hercynienne de Galice (Espagne). Geologie Alpine, 44,157-280.
Parga Pondal, I., Matte, Ph., Capdevila, R., 1964. Introduction a la géologie de l’ “Ollo de Sapo “, Formación porphyroïde antésilurienne du Nord Ouest de L’Espagne. Madrid, Instituto Geológico Minero España, Notas Comunicaciones, 76, 119-154.
Parrish, R.R., 1987. An improved micro-capsule for zircon dissolution in U-Pb geochronology. Chemical Geology (Isotope Geoscience Section), 66, 99-102.
Parrish, R.R., Roddick, J.C., Loveridge, W.D., Sullivan, R.W., 1987, Uranium-lead analytical techniques at the geochronology laboratory. Geological Survey of Canada. Radiogenic Age and Isotopic Studies, Report 1, Geological Survey of Canada, 87-2, 3-7.
Pearce, J.A., Harris, N.B.W., Tindle, A.G., 1984. Trace element discriminations for the tectonic interpretation of granitic rocks. Journal of Petrology, 25, 956-983.
Pérez Estaún, A., Martínez Catalán, J.R., Bastida, J., 1991. Crustal thickening and deformation sequence in the footwall to the suture of the Variscan belt of northwest Spain. Tectonophysics, 191, 243-253.
Pupin, J.P., 1980. Zircon and Granite Petrology. Contributions to Mineralogy and Petrology, 73, 207-220.
Ribeiro, A., 1974. Contribution à l´étude tectonique de Trás-osMontes oriental. Memória Serviços Geológicos de Portugal,
, 1-168.
Ribeiro, A., Pereira, E., Dias, R., 1990. Structure in the NW of the Iberian peninsula. In: Dallmeyer, R.D., Martínez García, E. (eds.). Pre-Mesozoic Geology of Iberia. Berlin Heildelberg, ed. Springer-Verlag, 221-236.
Roddick, J.C., Loveridge, W.D., Parrish, R.R., 1987. Precise U/Pb dating of zircon at the sub-nanogram Pb level. Chemical Geology (Isotope Geoscience Section), 66, 111-121.
Rodríguez, R., Marcos, A., Farias, P., 2004. Palinological data on the age of the metasediments of the Parautochthonous Thrust Sheet in the Cabo Ortegal area (Galicia, NW Spain). Neues Jarbuch für Geologie und Paläontologie, 10, 437-447.
Romariz, C., 1969. Graptolites silúricos do NW peninsular. Comunicaçoes Serviços Geológicos de Portugal, 53, 107-156.
Stacey, J.S., Kramers, J.D., 1975. Approximation of terrestrial lead isotope evolution by a two-stage model. Earth and
Planetary Science Letters, 26, 207-221.
Tucker, R.B., McKerrow, W.S., 1995. Early Paleozoic chronology: a review in light of new U-Pb zircon ages from Newfoundland and Britain. Canadian Journal of Earth Sciences, 32, 368-379.
van der Meer Mohr, C.G., 1975. The Palaeozoic strata near Moeche in Galicia, NW Spain. Leidse Geologische Mededelingen, 49, 32-37.
Valverde-Vaquero, P., Dunning, G.R., 2000. New U-Pb ages for Early Ordovician magmatism in Central Spain. Journal Geological Society, 157, 15-26.
Vogel, D.E., Engels, J.P., Ho Len Fat, A.G., 1967. Geological map of the area around Cabo Ortegal (Spain). The Geological Institute, Leiden (Nederlands).
Winchester, J.A., Floyd, P.A., 1977. Geochemical discrimination of different magma series and their differentiation products using inmobile elements. Chemical Geology, 20, 326-348.
Whalen, J.B., Longstaffe, F.J., Jenner, G.A., Robert, F., Gariépy, C., 1996. Geochemical and isotopic (Nd, O, Pb and Sr) constraints on A-type granite petrogenesis based on the Topsails igneous suite, western Newfoundland. Journal of Petrology, 37, 1463-1489.
York, D., 1969. Least-squares fitting of a straight line with correlated errors. Earth and Planetary Science Letters, 5, 320-324.
Downloads
Published
Issue
Section
License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Copyright
Geologica Acta is the property of the UB, GEO3BCN, IDAEA and UAB. Geologica Acta must be cited for any partial or full reproduction. Papers are distributed under the Attribution-Share Alike Creative Commons License. This license allows anyone to reproduce and disseminate the content of the journal and even make derivative works crediting authorship and provenance and distributing possible derivative works under the same or an equivalent license.
Author Rights
Authors retain the copyright on their papers and are authorized to post them on their own web pages or institutional repositories. The copyright was retained by the journal from the year 2003 until 2009. In all cases, the complete citation and a link to the Digital Object Identifier (DOI) of the article must be included.
The authors can use excerpts or reproduce illustrations of their papers in other works without prior permission from Geologica Acta provided the source of the paper including the complete citation is fully acknowledged.
