Hostname: page-component-745bb68f8f-lrblm Total loading time: 0 Render date: 2025-01-09T23:13:52.858Z Has data issue: false hasContentIssue false
  • English
  • Français

U-Pb geochronology of felsic volcanic rocks hosted in the Gafo Formation, South Portuguese Zone: the relationship with Iberian Pyrite Belt magmatism

Published online by Cambridge University Press:  05 July 2018

D. R. N. Rosa ,
A. A. Finch ,
T. Andersen  and
C. M. C Inverno
D. R. N. Rosa*
Affiliation:
INETI-Geological Survey, Estrada da Portela-Zambujal, Alfragide, 2720-866 Amadora, Portugal
A. A. Finch
Affiliation:
School of Geography and Geosciences, Irvine Building, North Street, St Andrews, Fife, KY16 9AL, UK
T. Andersen
Affiliation:
Department of Geology, University of Oslo, PO Box 1047 Blindern, N-0316 Oslo, Norway
C. M. C Inverno
Affiliation:
INETI-Geological Survey, Estrada da Portela-Zambujal, Alfragide, 2720-866 Amadora, Portugal
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Felsic volcanic rocks exposed in the Frasnian Gafo Formation, in the Azinhalinho area of Portugal, display very similar geochemical signatures to volcanic rocks from the Iberian Pyrite Belt (IPB). located immediately to the south. The similarities include anomalously low high field-strength elements (HFSE) concentrations, possibly caused by low-temperature crustal melting, which translate into classification problems.

A geochronological study, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of zircon grains from these rocks, has provided concordia ages of 356±1.5 Ma and 355±2.5 Ma for two samples of rhyodacite porphyry, and 356±1.4 Ma for a granular rhyodacite. These results show that volcanism at Azinhalinho was broadly contemporaneous with IPB volcanism, widely interpreted as being of Famennian to Visean age. Considering that the host rocks of the Azinhalinho volcanic rocks are Frasnian, and therefore deposited synchronously with the Upper Devonian Phyllite-Quartzite Group sedimentation in the IPB basin, the radiometric ages imply that the Azinhalinho felsic rocks are intrusive and likely represent conduits or feeders to the volcanism of the IPB.

Keywords

U-PbzircongeochronologyLA-ICP-MSIberian Pyrite Belt
Type
Research Article
Information
Mineralogical Magazine , Volume 72 , Issue 5 , October 2008 , pp. 1103 - 1118
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

†

also at: Geology Department/CREMINER-University of Lisbon, Edifício C6, Piso 2, 1749-016 Lisboa, Portugal

‡

also at: CREMINER-University of Lisbon, Edifício C6, Piso 4, 1749-016 Lisboa, Portugal

References

Andersen, T., Graham, S. and Sylvester, A.G. (2007) Timing and tectonic significance of Sveconorwegian A-type granitic magmatism in Telemark, southern Norway: New results from laser-ablation ICPMS U-Pb dating of zircon. Norges Geologiske Underskelse, 447, 17–31.Google Scholar
Andersen, T., Griffin, W.L., Jackson, S.E., Knudsen, T.L. and Pearson, NJ. (2004) Mid-Proterozoic magmatic arc evolution at the southwest margin of the Baltic Shield. Lithos, 73, 289–318.CrossRefGoogle Scholar
Barrie, C.T., Amelin, Y. and Pascual, E. (2002) U-Pb geochronology of VMS mineralization in the Iberian Pyrite Belt. Mineralium Deposita, 37, 684–703.CrossRefGoogle Scholar
Belousova, E.A., Griffin, W.L. and O'Reilly, S.Y. (2006) Zircon crystal morphology, trace element signatures and Hf isotope composition as a tool for petrogenetic modeling: examples from Eastern Australian granitoids. Journal of Petrology, 47, 329–353.CrossRefGoogle Scholar
Black, L.P., Kamo, S.L., Allen, CM., Davis, D.W., Aleinikoff, J.N., Valley, J.W., Mundil, R., Campbell, I.H., Korscha, R.J., Williams, I.S. and Foudoulis, C. (2004) Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS and oxygen isotope documentation for a series of zircon standards. Chemical Geology, 205, 115–140.CrossRefGoogle Scholar
Dunning, G.R., Diez Montes, A., Matas, J., Martin Parra, L.M., Almarza, J. and Donaire, M. (2002) Geocronologia U/Pb del volcanismo ácido y granitoides de la Faja Píritica Ibérica (Zona Surportuguesa). Geogaceta, 32, 127–130.Google Scholar
Gradstein, F.M., Ogg, J.G. and Smith, A.G. (2004) A Geologic Time Scale. Cambridge University Press, Cambridge, UK, 610 pp.Google Scholar
Jackson, S.E., Pearson, N.J., Griffin, W.L. and Belousova, E.A. (2004) The application of laser ablation-inductively coupled plasma-mass spectro-metry to in-situ U-Pb zircon geochronology. Chemical Geology, 211, 47–69.CrossRefGoogle Scholar
Julivert, M., Fontbote, J.M., Ribeiro, A. and Conde, L. (1972) Mapa tectonico de la Peninsula Ibérica y Baleares, 1/1.000.000. Institute Geologico Minero de Espana.Google Scholar
Le Maitre, R.W., Bateman, P., Dudek, A., Keller, J., Lameyre, J., Le Bas, M.J., Sabine, P.A., Schmid, R., Sorensen, H., Streckeisen, A., Woolley, A.R. and Zanettin, B. (editors) (1989) A Classification of Igneous Rocks and Glossary of Terms. Blackwell, Oxford, UK, 193 pp.Google Scholar
Lentz, D.R. (1999) Petrology, geochemistry, and oxygen isotope interpretation of felsic volcanic and related rocks hosting the Brunswick 6 and 12 massive sulfide deposits (Brunswick Belt), Bathurst Mining camp, New Brunswick, Canada. Economic Geology, 94, 57–86.CrossRefGoogle Scholar
Ludwig, K.R. (2003) ISOPLOT 3.0. A Geochronological Toolkit for Microsoft Excel™ Berkeley Geochronology Center Special Publication, 4, 70 pp.Google Scholar
Munhá, J. (1990) Metamorphic evolution of the South Portuguese/Pulo do Lobo Zone. Pp. 363–368 in: Pre-Mesozoic Geology of Iberia(Dallmeyer, R.D. and E., Martinez Garcia, editors). Springer-Verlag, Berlin Heidelberg New York.CrossRefGoogle Scholar
Oliveira, J.T. (editor) (1988) Notícia Explicativa da Folha 8, Carta Geolbgica de Portugal 1/200.000. Servicos Geologicos Portugal, 91 pp.Google Scholar
Oliveira, J.T., Relvas, J.M.R.S., Pereira, Z., Matos, J.X., Rosa, C.J., Rosa, D., Munha, J.M., Jorge, R.C.G.S. and Pinto, A.M.M. (2006) O Complexo vulcano-sedimentar da Faixa Piritosa: Estratigrafía, vulcanismo, mineralizačões associadas e evolučão tectono-estratigrafica no contexto da Zona Sul-Portuguesa. Pp. 207–243 in: Geologia de Portugal no contexto da Iberia(Dias, R., Araujo, A., Terrinha, P. and Kullberg, J.C., editors). Universidade de Évora, Évora, Portugal.Google Scholar
Pearce, J.A., Harris, N.B.W. and Tindle, A.G. (1984) Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25, 956–983.CrossRefGoogle Scholar
Pereira, Z., Fernandes, P. and Oliveira, J.T. (2006) Palynostratigraphy of the Pulo do Lobo Domain, South Portuguese Zone. Pp. 649–652 in: Proceedings of the VII Portuguese Geological Congress, Evora, Portugal.Google Scholar
Piercey, S.J., Pardais, S., Murphy, D.C. and Mortensen, J.K. (2001) Geochemistry and paleotectonic setting of felsic volcanic rocks in the Finlayson Lake volcanic-hosted massive sulfide district, Yukon, Canada. Economic Geology, 96, 1877–1906.Google Scholar
Pupin, J.P. (1980) Zircon and granite petrology. Contributions to Mineralogy and Petrology, 73, 207–220.CrossRefGoogle Scholar
Quesada, C. (1991) Geological constraints on the Paleozoic tectonic evolution of teetonostratigraphic terranes in the Iberian massif. Tectonophysics, 185, 225–245.CrossRefGoogle Scholar
Rohr, T.S., Andersen, T. and Dypvik, H. (2008) Provenance of Lower Cretaceous sediments in the Wandel Sea Basin, North Greenland. Journal of the Geological Society, 165, 755–767.CrossRefGoogle Scholar
Rosa, D.R.N., Inverno, C.M.C., Oliveira, V. and Rosa, C. (2004) Geochemistry of volcanic rocks, Albernoa area, Iberian Pyrite Belt, Portugal. International Geology Review, 46, 366–383.CrossRefGoogle Scholar
Rosa, D.R.N., Inverno, C.M.C., Oliveira, V. and Rosa, C. (2006) Geochemistry and geothermometry of volcanic rocks from Serra Branca, Iberian Pyrite Belt, Portugal. Gondwana Research, 10, 328–339.CrossRefGoogle Scholar
Rosa, D.R.N., Finch, A.A., Andersen, T. and Inverno, C.M.C. (2009) U-Pb geochronology and Hf isotope ratios of magmatie zircons from the Iberian Pyrite Belt. Mineralogy and Petrology, 95, 47–69.CrossRefGoogle Scholar
Silva, J.B., Oliveira, J.T. and Ribeiro, A. (1990) South Portuguese Zone. Structural outline. Pp. 348–362 in: Pre-Mesozoic Geology of Iberia(Dallmeyer, R.D. and E., Martinez Garcia, editors). Springer-Verlag, Berlin Heidelberg New York.CrossRefGoogle Scholar
Simonetti, A., Heaman, L.M., Hartlaub, R.P., Creaser, R.A., MacHattie, T.G. and Bohm, C. (2005) U-Pb zircon dating by laser ablation-MC-ICP-MS using a new multiple ion counting Faraday collector array. Journal of Analytical Atomic Spectrometry, 20, 677–686.CrossRefGoogle Scholar
Slama, J., Kosler, J., Condon, D.J., Crowley, J.L., Gerdes, A., Hanchar, J.M., Horstwood, M.S.A., Morris, G.A., Nasdala, L., Norberg, N., Schaltegger, U., Schoene, B., Tubrett, M.N. and Whitehouse, M.J. (2008) Plesovice zircon — A new natural reference material for U-Pb and Hf isotopic microanalysis. Chemical Geology, 249, 1–35.CrossRefGoogle Scholar
Taylor, J.R. (1997) An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements, 2nd edition. University Science Books, Sausalito, California, USA, 327 pp.Google Scholar
van Achterbergh, E., Ryan, C.G., Jackson, S.E. and Griffin, W.L. (2000) Data Reduction software for LA-ICPMS: Appendix. Pp. 239–243 in: Laser Ablation-ICP-Mass Spectrometry in the Earth Sciences: Principles and Applications(Sylvester, P.J., editor). Mineralogical Association of Canada Short Course Series, 29.Google Scholar
Wiedenbeck, M., Alle, P., Corfu, F., Griffin, W.L., Meier, M., Oberli, F., von Quadt, A., Roddick, J.C. and Spiegel, W. (1995) Three natural zircon standards for U-Th-Pb, Lu-Hf, trace element and REE analyses. Geostandards Newsletter, 19, 1–23.CrossRefGoogle Scholar
Winchester, J.A. and Floyd, P.A. (1977) Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chemical Geology, 20, 325–343.CrossRefGoogle Scholar