¡Nos trasladamos! E-Prints cerrará el 7 de junio.

En las próximas semanas vamos a migrar nuestro repositorio a una nueva plataforma con muchas funcionalidades nuevas. En esta migración las fechas clave del proceso son las siguientes:

Es muy importante que cualquier depósito se realice en E-Prints Complutense antes del 7 de junio. En caso de urgencia para realizar un depósito, se puede comunicar a docta@ucm.es.

From Rodinia to Pangaea: Ophiolites from NW Iberia as witness for a long-lived continental margin



Downloads per month over past year

Sánchez Martínez, Sonia and Arenas Martín, Ricardo and Fernández Suárez, Javier and Jeffries, Teresa E. (2009) From Rodinia to Pangaea: Ophiolites from NW Iberia as witness for a long-lived continental margin. Special publication - Geological Society of London, 327 . pp. 317-341. ISSN 0305-8719

[thumbnail of From Rodinia to Pangaea_ Ophiolites from NW Iberia as witness for a long-lived continental margin.pdf] PDF
Restringido a Repository staff only


Official URL: http://dx.doi.org/10.1144/SP327.14


The ophiolites preserved in the Variscan suture of NW Iberia (Galicia) show a broad variability in lithology, geochemistry and chronology. This wide variety rules out the simplest plate tectonic scenario in which these ophiolites would have been exclusively related to the oceanic domain closed during the final Pangaea assembly, that is the Rheic Ocean. The ophiolitic units from Galicia also provide important data about the palaeogeography immediately preceding the opening of this ocean, and some information about pre-Gondwanan supercontinent cycles. Six different ophiolites can be distinguished in the allochthonous complexes of Galicia: the Purrido, Somozas, Bazar, Vila de Cruces, Moeche and Careón units. The Purrido Ophiolite is constituted by metagabbroic amphibolites with igneous protoliths dated at 1159 ± 39 Ma (Mesoproterozoic), and geochemical affinities typical of island-arc tholeiites. These mafic rocks can be interpreted as one of the scarce members of the pre-Rodinian ophiolites, and they were probably generated in a back-arc setting in the periphery of the West African Craton. The Somozas Ophiolitic Mélange consists of a mixing of submarine volcanic rocks (pillow-lavas, submarine breccias, pillow-breccias, hyaloclastites), diabases, gabbros, microgabbros, diorites and granitoids, surrounded by a matrix of serpentinites or, less frequently, phyllites. Two granitic samples from this mélange yield U-Pb ages ranging between c. 527 and 503 Ma (Cambrian), which together with the characteristic arc signatures obtained in all the studied igneous rocks suggest that this ophiolite was generated in a peri-Gondwanan volcanic arc. The Bazar Ophiolite is formed by different tectonic slices with high temperature amphibolites, granulites, metagabbros and ultramafic rocks. The amphibolites are the most abundant rock type and show typical N-MORB compositions with igneous protoliths dated at 498 ± 2 Ma (Cambrian). The high-temperature metamorphism affecting some parts of the unit has been dated at c. 480 Ma (lower Ordovician), and it is considered to be related to the development of an oceanic accretionary complex under the volcanic arc represented by the upper units of the allochthonous complexes of Galicia. Considering the most common palaeogeographic reconstructions for the Cambrian period, it is suggested that the oceanic lithosphere represented by the Bazar Ophiolite was formed into the peri-Gondwanan oceanic domain prior to the rifting of the Avalonian microcontinent, that is the Iapetus-Tornquist Ocean. According to current data about the Vila de Cruces Unit, it can be interpreted as a composite terrane, whose lithologies have U-Pb ages ranging from 1176-497 Ma, but constituted by metaigneous rocks with arc signatures. This dataset has been interpreted in relation to the development of a back-arc basin around the Cambrian-Ordovician limit, involving a Mesoproterozoic basement and the reactivation of a former suture. The opening of this back-arc basin can also be identified as the birth of the Rheic Ocean, and probably it would also include the lithological succession belonging to the Moeche Unit, although its basic rocks exhibit compositions with more oceanic character. Finally, the Careón Ophiolite includes remnants of an oceanic lithosphere generated in a supra-subduction zone setting at 395 ± 2 Ma (middle Devonian). This ophiolite was formed in a contractive Rheic Ocean, shortly preceding the closure of this ocean. This is the only ophiolite in Galicia that can be related to mature stages of the Rheic Ocean, although as it is commonly observed in other regions the N-MORB crust is not preserved. This common oceanic crust has disappeared during subduction, probably in an intra-oceanic setting and during the generation of the igneous section preserved in the Careón Ophiolite.

Item Type:Article
Subjects:Sciences > Geology > Geodynamics
Sciences > Geology > Stratigraphic geology
Sciences > Geology > Petrology
ID Code:76771
Deposited On:24 Feb 2023 08:46
Last Modified:24 Feb 2023 08:46

Origin of downloads

Repository Staff Only: item control page