López-Moro, F.J.; Díez-Montes, A.; Timón-Sánchez, S.M.; Llorens-González, T.; Sánchez-García, T. Peraluminous Rare Metal Granites in Iberia: Geochemical, Mineralogical, Geothermobarometric, and Petrogenetic Constraints. Minerals2024, 14, 249.
López-Moro, F.J.; Díez-Montes, A.; Timón-Sánchez, S.M.; Llorens-González, T.; Sánchez-García, T. Peraluminous Rare Metal Granites in Iberia: Geochemical, Mineralogical, Geothermobarometric, and Petrogenetic Constraints. Minerals 2024, 14, 249.
López-Moro, F.J.; Díez-Montes, A.; Timón-Sánchez, S.M.; Llorens-González, T.; Sánchez-García, T. Peraluminous Rare Metal Granites in Iberia: Geochemical, Mineralogical, Geothermobarometric, and Petrogenetic Constraints. Minerals2024, 14, 249.
López-Moro, F.J.; Díez-Montes, A.; Timón-Sánchez, S.M.; Llorens-González, T.; Sánchez-García, T. Peraluminous Rare Metal Granites in Iberia: Geochemical, Mineralogical, Geothermobarometric, and Petrogenetic Constraints. Minerals 2024, 14, 249.
Abstract
The intensive variables, geochemical, mineralogical and petrogenetic constraints of the Iberian rare metal granites, many of them unknown, are presented. It allows to distinguish two main granitic types with contrasting characteristics: Nb-Ta-rich granites and Nb-Ta-poor granites. The former have lower emplacement temperatures, higher water contents and probably lower emplacement pressures than Nb-Ta-poor granites. Nb-Ta-rich granites also have higher fluoride contents, strong fractionation into twin pairs such as Zr-Hf, Y-Ho and Nb-Ta, and an abundant, probably exsolved, fluid phase, which is not or not as evident in Nb-Ta-poor granites, probably in part because the Nb-Ta-rich granites reach their solidus later (about 550 ºC). The geochemical signature of the Iberian rare metal granites follows the trends of mainly two-mica granites and P-rich cordierite granites, but also of granodiorites and even type I granites, suggesting that the rare metal granites may have different parental magmas. Thermodynamic modeling shows that many of the geochemical characteristics of the RMGs can be explained by a process of extreme differentiation, while others cannot, e.g. Na evolution. In terms of ore deposition, white mica plays a very important role in explaining the variation of the Ta/Nb ratio, although the latter could also be controlled by late Nb-Ta oxides crystallization and even by acidic fluids that remove Nb relative to Ta from earlier Nb-Ta oxides.
Environmental and Earth Sciences, Geochemistry and Petrology
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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