Coeval interaction between magmas of contrasting composition (Late Carboniferous-Early Permian Santa Eulália-Monforte massif, Ossa-Morena Zone) : field relationships and geochronological constraints
Pereira, M. F. (Universidade de Évora. Departamento de Geociências)
Gama, C. (Universidade de Évora. Departamento de Geociências)
Rodríguez, Carmen (Universidad de Huelva. Departamento de Ciencias de la Tierra)

Data:	2017
Resum:	The Santa Eulália-Monforte massif is a post-kinematic Late Carboniferous-Early Permian calc-alkaline composite massif (LC-EP) located in the Ossa-Morena Zone (OMZ, Portugal). This paper examines the field relationships between pinkish granites and mafic-intermediate rocks from the external ring of this massif and presents new U-Pb zircon age determinations. The estimated 206Pb/238U ages, 297±4Ma for the pinkish granite and 303±3Ma for a gabbro-diorite point to a short time interval between the crystallization of both magmas. At outcrop scale, contacts of the mafic-intermediate rocks with the host pinkish granite are sharp and corroborate this age relationship, but do not justify why the host-enclave contacts often has curved and irregular shapes, indicating liquid-liquid interaction. A full analysis of the distribution of U-Pb zircon ages and respective Th/U ratios suggests that the compositionally distinct magmas were roughly contemporaneous. The obtained ages also fit the LC-EP Iberian calc-alkaline suite that was formed contemporaneously to the development of the Iberian-Armorican Arc and when the Paleotethyan oceanic Plate subducted under the Eurasian active margin. Taking this geodynamic setting as a reference, the LC-EP Iberian calc-alkaline magmatism can be interpreted as most probably related to the Cimmerian cycle instead of the traditionally accepted model that ascribe a closer connection of this magmatism with the Variscan cycle.
Drets:	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, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Iberian massif ; Late carboniferous-early permian ; Calc-alkaline bimodal plutonism ; Zircon dating ; Variscan and cimmerian cycles
Publicat a:	Geologica acta, Vol. 15 Núm. 4 (December 2017) , p. 409-428, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/330807
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2017.15.4.10
DOI: 10.1344/GeologicaActa2017.15.4.10

28 p, 7.2 MB

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