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

• Published in: Mineralogy and petrology 2017-02, Vol.111 (1), p.1-21
• Main Authors: Van Lichtervelde, Marieke, Grand’Homme, Alexis, de Saint-Blanquat, Michel, Olivier, Philippe, Gerdes, Axel, Paquette, Jean-Louis, Melgarejo, Joan Carles, Druguet, Elena, Alfonso, Pura
• Format: Article
• Language: English
• Subjects: Age; Analysis; Cap de Creus; Carboniferous; Catalunya; Columbite Group; Columbite-group minerals; Crystallization; Earth and Environmental Science; Earth Sciences; Enginyeria civil; Evolution; Fractionation; Geochemistry; Geochronology; Geologia; Geological time; Grup de la Columbita; Inorganic Chemistry; Mineralogia; Mineralogy; Minerals; Original Paper; Pegmatite; Pegmatites; Permian; Plate tectonics; Radioactive age determination; Sciences of the Universe; Spain; Studies; Xenotime; Zircon; Àrees temàtiques de la UPC
• ISSN: 0930-0708; 1438-1168
• DOI: 10.1007/s00710-016-0455-1

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.