Ta and Sn concentration by muscovite fractionation and degassing in a lens-like granite body: The case study of the Penouta rare-metal albite granite (NW Spain)
A single pulse of granite melt was subhorizontally emplaced evolving upwards. Columbite-tantalite crystallized in non-equilibrium conditions and did not fractionate Ta or Nb. Ta/Nb concentration in the melt was mainly due to muscovite removal in emplacement place. Lower margin degassing could promote Sn enrichment in the central part of the granite. Geometry and age of the albite granites help to cooling and vapour saturation.