EES Virtual Seminar: Rare metal granites - Variscan examples, characteristics and origin
Michel Pichavant, Université D'Orléans
Rare-metal granites (RMGs) are exceptional natural objects which occur in different geological settings. These highly geochemically specialized granites are associated with Sn, W, Cs, Nb, Ta mineralization and considered to play an important role in ore-forming processes. The characteristic geological, petrographical, mineralogical and geochemical features of Variscan RMGs are illustrated on a representative example, the Argemela granite (Central Iberian Zone, Portugal). RMGs, in particular the phosphorus-rich types, are generated by anatexis of crustal sources. However, recent experimental studies demonstrate difficulties with an origin of RMGs by partial melting only. This stresses the importance of fractionation which involve melt-crystal, fluid-melt and crystal-fluid equilibration mechanisms superimposed during the granite evolution.
Online via Zoom
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