Age of the basement beneath the Mesozoic Lusitanian Basin revealed by granitic xenoliths from the Papôa volcanic breccia (West Iberia)
Pereira, M. F. (Universidade de Évora. Instituto de Ciências da Terra)
Gama, C. (Universidade de Évora. Instituto de Ciências da Terra)
Silva, J. B. (Universidade de Lisboa. Departamento de Geologia)
Dias da Silva, Í. (Universidade de Lisboa. Departamento de Geologia)

Date:	2020
Abstract:	The dyke of the Papôa volcanic breccia cross-cutting the Lower Jurassic sequence of the Lusitanian Basin (West Iberia) contains granitic xenoliths. In this study, for the first time, U-Th-Pb zircon analysis of two xenoliths yielded 298 ± 4 Ma for biotite granite and of 292 ± 2 Ma for two-mica granite, indicating that the pre-Mesozoic basement of the Lusitanian Basin includes Permian intrusions. These ages are close within the margin of error of the age of the Late Carboniferous granites of the Berlengas isle that with the Late Devonian high-grade metamorphic rocks of the Farilhões isles, located northwest of the study area, which form the pre-Mesozoic basement of the Lusitanian Basin. These new geochronological findings enable it to be established that Permo-Carboniferous magmatism lasted at least 13 Ma, in this region of the Appalachian-Variscan belt. Furthermore, a comparison with available data from Paleozoic tectonic units of the Appalachian-Variscan belt located both in the Iberian Massif and outside it enables the suggestion to be made that the Lusitanian Basin (Peniche) most probably rests on the South Portuguese Zone, which may also be correlated with the Rhenohercynian Zone present in southwest England, and the Meguma terrane of Nova Scotia.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Pyroclastic breccia ; Xenoliths ; Granitic rocks ; Permian plutonism ; U-pb zircon dating
Published in:	Geologica acta, Vol. 18 (2020) , p. 1-19 (Articles) , ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/375285
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2020.18.16
DOI: 10.1344/GeologicaActa2020.18.16

17 p, 7.5 MB

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