U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites, NE Spain - Archive ouverte HAL
Article Dans Une Revue Mineralogy and Petrology Année : 2017

U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites, NE Spain

Résumé

The Cap de Creus granitic pegmatites in the eastern Catalan Pyrenees were dated using in situ U-Pb geochronology by laser ablation ICP-MS on zircon and columbite-group minerals (CGM), which are present in the different types of pegmatites from type I (K-feldspar pegmatites, least evolved) to type IV (albite pegmatites, most evolved) and therefore allow dating the different pegmatitic pulses. In a type III pegmatite where zircon and CGM are co-genetically associated in the same sample, both minerals were dated using zircon and tantalite reference materials, respectively, to avoid laser-induced matrix-dependent fractionation. In one sample, xenotime genetically associated with zircon was also dated. Two ages were obtained for type I and three ages for type III pegmatites. Three of these 5 ages range from 296.2 ± 2.5 to 301.9 ± 3.8 Ma and are allocated to the primary magmatic stage of crystallization and therefore to the emplacement event. Two younger ages (290.5 ± 2.5 and 292.9 ± 2.9 Ma) obtained on secondary zircon and xenotime, respectively, are interpreted as late post-solidus hydrothermal remobilization. There is no age difference between type I and type III pegmatites. The mean 299 Ma primary magmatic age allows the main late Carboniferous deformation event to be dated and is also synchronous with other peraluminous and calc-alkaline granites in the Pyrenees. However, the youngest ages around 292 Ma imply that tectonics was still active in Early Permian times in the Cap de Creus area.

Domaines

Géochimie

Dates et versions

hal-01457075 , version 1 (06-02-2017)

Identifiants

Citer

Marieke van Lichtervelde, Alexis Grand'Homme, Michel de Saint Blanquat, Philippe Olivier, Axel Gerdes, et al.. U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites, NE Spain. Mineralogy and Petrology, 2017, 111, pp.1-21. ⟨10.1007/s00710-016-0455-1⟩. ⟨hal-01457075⟩
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