A revised Ordovician age for the Miranda do Douro orthogneiss, Portugal. Zircon U-Pb ion-microprobe and LA-ICPMS dating

F. BEA, P. MONTERO, C. TALAVERA, T. ZINGER

Abstract


The Miranda do Douro orthogneiss was believed to be the oldest magmatic rock of the Central Iberian Zone, on the base of a U-Pb discordia upper intercept of 618 ± 9 Ma. Nevertheless, new ion-microprobe and LA-ICPMS U-Pb zircon dating revealed that the crystallization age was 483 ± 3 Ma. The orthogneiss also contains a 605 ± 13 Ma zircon population that indicates that the source-rock for the Ordovician magma was Pan-African. Moreover, a few ~3.17 Ga zircon grains were also recorded. These grains are the oldest found so far in Iberia, and its occurrence would suggest the involvement of an Archean crust in the Pan-African orogeny.

Keywords


U-Pb dating. Ollo de Sapo. Pre-Variscan. Central Iberian Zone. Gneiss

Full Text:

PDF


DOI: https://doi.org/10.1344/105.000000353

Refbacks

  • There are currently no refbacks.


Bookmark and Share


Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike License.
                                                                                                                            
            Facultat de Ciències de la Terra                  Institut de Ciències de la Terra                     Institut de Diagnosi Ambiental                    Universitat Autònoma de Barcelona           
                Universitat de Barcelona                            "Jaume Almera" (CSIC)                              i Estudis de l'Aigua (CSIC) 
 
 
Geologica Acta (ISSN-1695-6133)
Biblioteca de Ciències de la Terra (UB-CSIC) | Facultat de Ciències de la Terra, Martí i Franquès s/n 08028 Barcelona | Spain
Phone: +34 93 403 19 89 | E-mail: geologica-acta@ictja.csic.es
RCUB revistesub@ub.edu Avís Legal RCUB Universitat de Barcelona