Rare-elements (Li-Be-Ta-Sn-Nb) magmatism in the European Variscan belt, a review
Résumé
The European Variscan belt, which is characterized by a huge amount of granitic intrusions, displays several significant rare-elements pegmatites and/or granites fields which could represent an important source of raw materials. An overview of these occurrences gave the possibility to discuss the processes at their origin and their common classification. Indeed, the spatial and temporal distributions of rare-element pegmatites in the European Variscan belt suggest that rare-elements magmatism would rather be related to local specific conditions (in particular sources, tectonic and thermal regime) than lower crustal processes like rare-elements enrichment subsequent to their release during granulite metamorphism. Actual classification of rare-elements pegmatites, based on their geochemistry and mineral composition, does notallow to discern pegmatites formed in different tectonic regimes and which exhibit various internal structures (e.g. the pegmatites of the lepidolite-subclass from Western Iberia and from the Moldanubian domain of the Bohemian Massif for example).
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