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The Vila de Cruces Ophiolite: A Remnant of the Early Rheic Ocean in the Variscan Suture of Galicia (Northwest Iberian Massif)

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Arenas Martín, Ricardo and Martínez Catalán, José Ramón and Sánchez Martínez, Sonia and Fernández Suárez, Javier and Andonaegui Moreno, Pilar and Pearce, Julian A. and Corfu, Fernando (2007) The Vila de Cruces Ophiolite: A Remnant of the Early Rheic Ocean in the Variscan Suture of Galicia (Northwest Iberian Massif). The Journal of geology, 115 . pp. 129-148. ISSN 0022-1376

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Abstract

The Vila de Cruces ophiolite is one of the ophiolitic units involved in the Variscan suture of the northwest Iberian
Massif. This ophiolite consists of a tectonically repeated succession of greenschist facies volcanic rocks, common
alternations of metasediments of pelitic or siliceous character, and scarce orthogneisses, metagabbros, and serpentinites.
The protolith age of a granitic orthogneiss that intruded the mafic rocks is dated at 497±4 Ma (U-Pb in
zircons). This age can be considered a reference for the generation of the ophiolite. According to their contents of
some of the most immobile trace elements, the greenschist and the metagabbros are derived from basaltic magmas
with compositions similar to those of island-arc tholeiites. The influence of a subduction zone in the generation of
the original basaltic magmas can be deduced from the marked negative Nb anomaly observed in all the metabasic
rocks of this ophiolite. The granitic orthogneisses can also be genetically related to the basic rocks because they are
similar to granitic rocks generated in volcanic arcs. The Vila de Cruces ophiolite is interpreted as a suprasubduction
zone ophiolite generated in Late Cambrian times, during the early stages of the opening of the Rheic Ocean. The
ophiolite was probably generated in a back-arc basin developed during the first stages of the pulling apart and later
drift of one or more peri-Gondwanan terranes, one of them represented by the upper allochthon of the northwest
Iberian Massif.


Item Type:Article
Uncontrolled Keywords:The Vila de Cruces Ophiolite; Variscan suture Galicia
Subjects:Sciences > Geology > Petrology
ID Code:17406
Deposited On:12 Dec 2012 11:55
Last Modified:12 Dec 2012 12:23

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