Tourmalines are the most important Fe-Mg minerals in the pegmatites and leucogranites intruding the crystalline core of the Western Tatra Mountains (South Poland). They also occur in the folded host rocks inside the contact zone. The chemical composition and the weak zonation of the investigated tourmalines are both consistent with the field observations which suggest their magmatic/late magmatic origin and a close association with the Li-poor leucogranites and Al-rich, Ca-poor metasediments. The irregular distribution of the tourmaline-bearing rocks can be interpreted as reflecting three factors, i.e., limited boron and water availability in the metasedimentary rocks during anatexis, variable oxygen fugacity (controlled partly by the presence of graphite) and restricted mobility of the mafic cations, necessary for tourmaline formation. The exsolution of a boron-rich fluid phase, incompatible with silicate melt, and its escape along a shear zone is also considered. The differences in Fe3+/Fe2+ characterising the Western Tatra tourmalines could result both from fO2 variations in the source metasediments during anatexis and from the interaction of magmatic/postmagmatic fluids with the metamorphic host rocks.

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