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STRATI 2013 pp 747-751 | Cite as

Provenance Analysis of Lower Palaeozoic Siliciclastic Rocks of Southwestern Iberia (Ossa–Morena Zone): Distal Shelf Deposition on the North Gondwana Passive Margin

  • M. F. PereiraEmail author
  • M. Chichorro
  • C. Lopes
  • A. M. R. Solá
  • J. B. Silva
  • M. Hofmann
  • U. Linnemann
Conference paper
Part of the Springer Geology book series (SPRINGERGEOL)

Abstract

U–Pb dating of detrital zircons from the lower Palaeozoic siliciclastic rocks of southwestern Iberia (the Ossa–Morena Zone or OMZ: comprising the Fatuquedo, Ossa, Colorada, and Terena formations) shows that sedimentation during the middle–late Cambrian to Early Devonian was marked by slight variations in the source areas, involving the denudation of crustal blocks with similar zircon-forming events typical of North Gondwana and the absence of volcanism younger than ca. 470 Ma. The potential source areas of the middle–upper Cambrian to Lower Devonian sediments of the basins of the OMZ could be the Neoproterozoic basement of the OMZ (the Série Negra) intruded by Cambrian and Early Ordovician plutonic rocks, and/or the lower Palaeozoic sedimentary sequences of the OMZ with Cambrian and Early Ordovician volcanics. In the oldest siliciclastic rocks, the most relevant populations of detrital zircons have Cryogenian and Ediacaran ages (the Ossa and Fatuquedo formations). Futhermore, in the youngest siliciclastic rocks, in addition to Cryogenian and Ediacaran zircon grains there are relevant clusters of Cambrian and Tonian ages (the Colorada Formation). Cambrian and Ordovician zircon ages found in the Lower Devonian greywackes (the Terena Formation) suggest intense denudation of the OMZ during the Early Devonian. No evidence was found of sources outside North Gondwana. The lack of zircon-forming events younger than ca. 470 Ma seems to indicate that the middle–upper Cambrian to Lower Devonian siliciclastic rocks of southwestern Iberia were deposited on a distal shelf of the North Gondwana passive margin related to the opening of the Rheic Ocean and in the absence of magmatic activity.

Keywords

U–Pb detrital zircon geochronology Middle–Upper Cambrian Ordovician Lower Devonian Rheic Ocean 

Notes

Acknowledgments

This paper is a contribution to research projects GONDWANA-PTDC/CTE-GIX/110426/2009 and GOLD- PTDC/GEO–GEO/2446/2012 funded by Fundação para a Ciência e Tecnologia (Portugal) and to IGCP projects 574 “Bending and bent orogens, and continental ribbons” and 597 “Amalgamation and breakup of Pangaea: the type example of the supercontinent cycle” (UNESCO-IUGS). It is a contribution to project PEst-OE/CTE/UI4073/2014.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • M. F. Pereira
    • 1
    Email author
  • M. Chichorro
    • 2
  • C. Lopes
    • 2
  • A. M. R. Solá
    • 3
  • J. B. Silva
    • 4
  • M. Hofmann
    • 5
  • U. Linnemann
    • 5
  1. 1.IDL, Departamento de Geociências, ECTUniversidade de ÉvoraÉvoraPortugal
  2. 2. CICEGe, Departamento de Ciências da Terra, Faculdade de Ciências e TecnologiaUniversidade Nova de LisboaCaparicaPortugal
  3. 3.Unidade de GeologiaLNEGLisbonPortugal
  4. 4.Departamento de Geologia, Faculdade de CiênciasUniversidade de LisboaLisbonPortugal
  5. 5.Senckenberg Naturhistorische Sammlungen DresdenDresdenGermany

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