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

作者：Van Lichtervelde Marieke^*; Grand'Homme Alexis; de Saint Blanquat Michel; Olivier Philippe; Gerdes Axel; Paquette Jean Louis; Carles Melgarejo Joan; Druguet Elena; Alfonso Pura

来源：Mineralogy and Petrology, 2017, 111(1): 1-21.

DOI：10.1007/s00710-016-0455-1

• Geochronology
• Pegmatites
• Cap deCreus
• Zircon
• Columbite-group minerals

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.

• 出版日期2017-2