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Tectonic Evolution of the Careón Ophiolite (Northwest Spain): A Remnant of Oceanic Lithosphere in the Variscan Belt

Díaz García, Florentino and Arenas Martín, Ricardo and Martínez Catalán, José Ramón and González del Tánago, José and Dunning, Gregory R. (1999) Tectonic Evolution of the Careón Ophiolite (Northwest Spain): A Remnant of Oceanic Lithosphere in the Variscan Belt. The Journal of geology, 107 . pp. 587-605. ISSN 0022-1376

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Abstract

Analysis of the Careoó Unit in the Ordenes Complex (northwest Iberian Massif) has supplied relevant data concerning
the existence of a Paleozoic oceanic lithosphere, probably related to the Rheic realm, and the early subduction-related
events that were obscured along much of the Variscan belt by subsequent collision tectonics. The ophiolite consists
of serpentinized harzburgite and dunite in the lower section and a crustal section made up of coarse-grained and
pegmatitic gabbros. An Early Devonian zircon age (395±2 Ma, U-Pb) was obtained in a leucocratic gabbro. The
whole section was intruded by numerous diabasic gabbro dikes. Convergence processes took place shortly afterward,
giving rise to a mantle-rooted synthetic thrust system, with some coeval igneous activity. Garnet amphibolite,
developed in metamorphic soles, was found discontinuously attached to the thrust fault. The soles graded downward
to epidote-amphibolite facies metabasite and were partially retrogressed to greenschist facies conditions. Thermobarometric
estimations carried out at a metamorphic sole (T ≈ 650ºC; P ≈ 11.5 kbar) suggested that imbrications
developed in a subduction setting, and regional geology places this subduction in the context of an early Variscan
accretionary wedge. Subduction and imbrication of oceanic lithosphere was followed by underthrusting of the Gondwana
continental margin.


Item Type:Article
Uncontrolled Keywords:Tectonic evolution; Oceanic Lithosphere; Variscan Belt
Subjects:Sciences > Geology > Petrology
Sciences > Geology > Geodynamics
ID Code:17405
Deposited On:12 Dec 2012 11:47
Last Modified:12 Dec 2012 12:21

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