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| DOI | 10.1016/J.JOG.2017.01.001 | ||||
| Año | 2017 | ||||
| Tipo | artículo de investigación |
Citas Totales
Autores Afiliación Chile
Instituciones Chile
% Participación
Internacional
Autores
Afiliación Extranjera
Instituciones
Extranjeras
The pre-Alpine basement of the Southern Carpathians/Western Balkans contains four ophiolitic massifs dismembered by Alpine tectonics, which define the "Balkan-Carpathian Ophiolite" (BCO) for which the tectonic setting and age of formation are still debated (Precambrian or Early Devonian). In this contribution, we demonstrate that, in light of a Pre-Alpine restoration, the four massifs belonged to a unique slice of very complete, obducted oceanic lithosphere and we re-evaluate its tectonic setting. Large chromitite volumes with Al-rich spinel compositions (Cr# = 0.39-0.48), as well as major and trace geochemical results on basalts (slightly enriched N-MORBs with low negative Nb anomaly associated with calk alkaline BABBs), point to a formation in a back-arc basin. Mantle spinel composition (Cr# = 0.49-0.51) and melting modeling indicate mean melting extents of 8.5-11% favouring intermediate spreading rate. New Sm-Nd dating on lower gabbroic rocks give a whole rock isochron, interpreted as the age of formation of the BCO crust at 409 +/- 38 Ma, thus confirming an Early Devonian oceanic crust. The previous 563 Ma U-Pb zircon age can be interpreted as casual inheritance indicating the proximity of an old continental lithosphere. Taking into account the lithological evidences and paleocontinental affinities of the two recognized terranes separated by the BC oceanic basin (Balkans and Sredna Gora) and by analogy with other Variscan ophiolites in Western/Central Europe, we suggest that the BC ophiolite belong to the similar to 400 Ma ophiolites group obducted between West and East Galatia and belonging to the southern Variscan suture. However, the BC ophiolite is the only one of this group obducted to the north and not involved in the Lower Allochthon/ophiolite/Upper Allochthon thrust pile, likely explaining its exceptional preservation. Finally, we tentatively propose a new unifying tectonic model where different terrane drift rates and highly oblique displacements create two Rheic branches, the "Rheic" and the "Galicia-Brittany-Massif Central". (C) 2017 Elsevier Ltd. All rights reserved.
| Ord. | Autor | Género | Institución - País |
|---|---|---|---|
| 1 | Plissart, Gaelle | - |
Universidad Austral de Chile - Chile
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| 2 | Monnier, C. | Hombre |
Univ Nantes - Francia
Université de Nantes - Francia Nantes Université - Francia |
| 3 | Diot, Herve | - |
Univ Nantes - Francia
Univ La Rochelle - Francia Université de Nantes - Francia Université de La Rochelle - Francia Nantes Université - Francia La Rochelle Université - Francia |
| 4 | Maruntiu, Marcel | Hombre |
IGR - Rumania
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| 5 | Berger, J. | Hombre |
Univ Paul Sabatier - Francia
Universite Paul Sabatier Toulouse III - Francia Université Toulouse III - Paul Sabatier - Francia |
| 6 | Triantafyllou, A. | Hombre |
Univ Nantes - Francia
Univ Mons - Bélgica Université de Nantes - Francia Université de Mons - Bélgica Nantes Université - Francia |
| Fuente |
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| Wallonie-Bruxelles International |
| Wallonie-Bruxelles International & FNRS, French and European Foreign Ministry, Ministry of Higher Education and Research as part of Hubert Curien partnerships (FNRS/CNRS) |
| Agradecimiento |
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| We acknowledge Karel Schulmann and an anonymous referee for their critical review that greatly improved the quality of this manuscript. Editor-in-Chief Irina Artemieva is also thanked by helping the final editing of this research paper. This work was supported by the scientific cooperation no 2.8.- 59/2008 between Romania and Belgium partly funded by Wallonie-Bruxelles International. It has been partly supported by Wallonie-Bruxelles International & FNRS, French and European Foreign Ministry, Ministry of Higher Education and Research as part of Hubert Curien partnerships (FNRS/CNRS 2009 y 2010). The data for this paper are available by contacting the corresponding author. We thank Carole La from the LPGN of the Universite de Nantes (France), and Vinciane Debaille and Wendy Debouge from the G-Time of the Universite Libre de Bruxelles (Belgium) for support during analytical sessions. |