Rare-earth elements mobility during hydrothermal alteration: the example of the Serra Branca granite, central Brazil

The Middle Proterozoic granitic massif, in the Goias Tin Province, is affected by pervasive post-magmatic hydrothermal alterations, chiefly by eastward, increasingly developed greisenization. Hydrothermal alteration results in strong mineralogical and chemical modifications of granite composition, but nevertheless the effect of fluid circulations is probably limited to a dilution of the initial REE content in magmatic rocks without any important fractionation, as suggested by the similarity between chondrite-normalized patterns for all rocks, from the less altered granite to the muscovite-topaz-bearing greisen. ((C) Academie des sciences / Elsevier, Paris.).