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Magmatism and early-Variscan continental subduction in the northern Gondwana margin recorded in zircons from the basal units of Galicia, NW Spain

2009; Geological Society of America; Volume: 122; Issue: 1-2 Linguagem: Inglês

10.1130/b26572.1

1943-2674

Jacobo Abati, Axel Gerdes, Javier Fernández‐Suárez, Ricardo Arenas, Martin J. Whitehouse, Rubén Díez Fernández,

earthquake and tectonic studies

Research Article| January 01, 2010 Magmatism and early-Variscan continental subduction in the northern Gondwana margin recorded in zircons from the basal units of Galicia, NW Spain Jacobo Abati; Jacobo Abati † 1Departamento de Petrología y Geoquímica and Instituto de Geología Económica, Universidad Complutense and Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain †E-mail: abati@geo.ucm.es Search for other works by this author on: GSW Google Scholar Axel Gerdes; Axel Gerdes 2Institut für Geowissenschaften, Mineralogie, Johann Wolfgang Goethe-Universität Frankfurt am Main, Altenhöferallee 1, D-60438 Frankfurt am Main, Germany Search for other works by this author on: GSW Google Scholar Javier Fernández Suárez; Javier Fernández Suárez 1Departamento de Petrología y Geoquímica and Instituto de Geología Económica, Universidad Complutense and Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain Search for other works by this author on: GSW Google Scholar Ricardo Arenas; Ricardo Arenas 1Departamento de Petrología y Geoquímica and Instituto de Geología Económica, Universidad Complutense and Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain Search for other works by this author on: GSW Google Scholar Martin J. Whitehouse; Martin J. Whitehouse 3Swedish Museum of Natural History, Stockholm, Sweden Search for other works by this author on: GSW Google Scholar Rubén Díez Fernández Rubén Díez Fernández 4Departamento de Geología, Universidad de Salamanca, 37008 Salamanca, Spain Search for other works by this author on: GSW Google Scholar Author and Article Information Jacobo Abati † 1Departamento de Petrología y Geoquímica and Instituto de Geología Económica, Universidad Complutense and Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain Axel Gerdes 2Institut für Geowissenschaften, Mineralogie, Johann Wolfgang Goethe-Universität Frankfurt am Main, Altenhöferallee 1, D-60438 Frankfurt am Main, Germany Javier Fernández Suárez 1Departamento de Petrología y Geoquímica and Instituto de Geología Económica, Universidad Complutense and Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain Ricardo Arenas 1Departamento de Petrología y Geoquímica and Instituto de Geología Económica, Universidad Complutense and Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain Martin J. Whitehouse 3Swedish Museum of Natural History, Stockholm, Sweden Rubén Díez Fernández 4Departamento de Geología, Universidad de Salamanca, 37008 Salamanca, Spain †E-mail: abati@geo.ucm.es Publisher: Geological Society of America Received: 31 Oct 2008 Revision Received: 26 Feb 2009 Accepted: 27 Feb 2009 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2010 Geological Society of America GSA Bulletin (2010) 122 (1-2): 219–235. https://doi.org/10.1130/B26572.1 Article history Received: 31 Oct 2008 Revision Received: 26 Feb 2009 Accepted: 27 Feb 2009 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Jacobo Abati, Axel Gerdes, Javier Fernández Suárez, Ricardo Arenas, Martin J. Whitehouse, Rubén Díez Fernández; Magmatism and early-Variscan continental subduction in the northern Gondwana margin recorded in zircons from the basal units of Galicia, NW Spain. GSA Bulletin 2010;; 122 (1-2): 219–235. doi: https://doi.org/10.1130/B26572.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract In situ uranium-lead dating (LA-SF-ICP-MS and SIMS) and Lu-Hf isotope analyses (LA-MC-ICP-MS) of zircon from eclogite facies rocks from the basal units of the Variscan Belt in Galicia constrain their magmatic and metamorphic evolution and give some clues about the nature and origin of the involved basement. The samples studied are two felsic gneisses, two eclogites, and one eclogitic gneiss of intermediate composition (metatonalite). Oscillatory-zoned zircon cores from the felsic samples gave a main clustering of U-Pb ages at 493 ± 2 and 494 ± 2 Ma, and some older ages that represent inherited cores. Zircon grains from the intermediate and one of the mafic rocks show no inherited cores and yielded ages of 494 ± 3 and 498 ± 6 Ma, respectively, interpreted as time of protolith crystallization. Variably developed homogeneous zircon rims in one felsic gneiss yielded an age of 372 ± 3 Ma, and very tiny zircons of one eclogite gave 350 ± 2 Ma, both of which we interpret as metamorphic ages.The new age data demonstrate that the calc-alkaline magmatic suite described in the basal unit is ca. 20 Ma older than the alkaline to peralkaline plutonic suite of the same unit (dated at 472 ± 2 Ma; Rodríguez et al., 2007), and thus probably represents a distinct geologic event. Overgrowth rims are interpreted as metamorphic on the basis of their Lu/Hf and Th/U ratios. The 372 ± 3 age is considered as dating the high-pressure (high-P) metamorphism, and is essentially in agreement with previous Ar-Ar and Rb-Sr data. This high-P metamorphism marks the initial early-Variscan subduction of the Gondwana margin. The inherited zircon ages and Hf isotopic composition of zircons point to a considerable input of crustal material with West African Craton provenance to the felsic magma. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.