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Título : Gravity and magnetic anomalies in the allochthonous Órdenes Complex (Variscan belt, northwest Spain): Assessing its internal structure and thickness
Autor : Martínez Catalán, José R. .
Álvarez Lobato, Fernando .
Pinto, Victor .
Gómez Barreiro, Juan .
Ayarza, Puy .
Villalaín, Juan José
Casas, Albert .
Publicado en: Tectonics, 2012, v. 31, n. 5, TC5007
Editorial : Wiley
American Geophysical Union
Fecha de publicación : oct-2012
ISSN : 0278-7407
DOI: 10.1029/2011TC003093
Resumen : The Órdenes Complex is the largest Variscan allochthonous structure of NW Iberia, and preserves the suture of a long-standing Paleozoic ocean, probably the Rheic. Gravity and magnetic data, the latter specifically acquired on land for this study, show that the complex occupies the core of an open synform with a maximum depth of 9–10 km, which contrasts with the flat geometry of the lower crust and Moho discontinuity beneath. The maximum depth reached by the ophiolitic rocks marking the suture is around 7 km. The allochthonous units formed by basic and ultrabasic rocks are lens-shaped in section, and occur not only at the periphery of the complex, but form wide ribbons trending NE-SW to N-S. The Bouguer anomaly related with the longest of them, the Fornás Unit, previously used to support an autochthonous interpretation of the complexes, is modeled as a rootless, massive amphibolite body with a maximum thickness of 6 km located at the downthrown block of a large normal fault cutting across previous thrust faults and extensional detachments. The main magnetic anomalies are associated with ultrabasic rocks cropping out in the NW and SE, but a weak, wide anomaly in the central part of the complex is related with one or more thin layers of amphibolite partly mineralized with massive sulphides. The weakly arcuate geometry of this anomaly and of the Bouguer anomaly caused by the Fornás Unit may reflect the NE flank of the Central Iberian arc, an orocline whose core is occupied by the allochthonous complexes.
Palabras clave: Órdenes Complex
NW Iberia
Variscan Belt
geophysical modeling
Materia: Paleontología
Paleontology
Magnetismo
Magnetism
Derechos: ©2012. American Geophysical Union
URI : http://hdl.handle.net/10259.4/2562
Versión del editor: http://onlinelibrary.wiley.com/doi/10.1029/2011TC003093/abstract
Aparece en las colecciones: Artículos PALEOMAG-UBU

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