Tourmalinites from the southern part of Svratka Crystalline Complex

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Acta Mus. Moraviae, Sci. Geol. 92 (2007), issue 1–2, pages 111–130
Article
Abstract:

Tourmalinites from the southern part of Svratka Crystalline Complex

Tourmalinites from the southern part of the Svratka Crystalline complex form stratiform layers hosted in mica schist. They probably represent a part of metamorphosed volcano-sedimentary complex primary rich in F and B. Whole rock composition of tourmalinites is close to the surrounding mica schists. P-T conditions 600–630 °C and 5–6 kbar calculated from associated mica schist were interpreted as retrograde metamorphism. Chemical composition of tourmaline strongly varies from high X-site vacant Al-rich schorl to dravite which indicate tourmaline growths over a range of P-T-X conditions. Tourmaline shows three distinct compositional domains (zone I, II, III): chemically inhomogeneous broken core (zone I), volumetrically minor zone II overgrown the core and volumetrically dominant outer zone III, chemically relatively homogeneous. Tourmaline type I correspond to Al-rich schorl with high vacancy and relatively low F (≤0.35 apfu) and it is interpreted as older, low temperature hydrothermal tourmaline. Tourmaline type II is dravite rich in F (≤0.5 apfu) and corresponds to prograde metamorphism. Tourmaline I overgrown by tourmaline II is usually enclosed in other minor minerals (kyanite, muscovite, biotite, garnet). Tourmaline III – Al-rich schorl-dravite formation probably occurred during retrograde metamorphism. Variability of all three tourmaline types is controlled mainly by the substitutions XYAlWOH XNa-1Y (Mg,Fe)-1WF-1 and YFeYMg-1.

Contact:

Renata Čopjaková, Radek Škoda, Institute of Geological Sciences, Masaryk University and Czech Geological Survey, Kotlářská 2, 611 37 Brno, Czech Republic, e-mail: copjakova@sci.muni.cz, rskoda@sci.muni.cz
David Buriánek, Czech Geological Survey, Leitnerova 23, Brno, e-mail: Burianek@cgu.cz
Stanislav Houzar, Department of Mineralogy and Petrography, Moravian Museum, Zelný trh 6, 659 37 Brno, e-mail: shouzar@mzm.cz

Citation:
Čopjaková, R., Buriánek, D., Škoda, R., Houzar, S., 2007: Turmalinity jižní části svrateckého krystalinika. – Acta Mus. Morav., Sci. Geol., 92, 1–2, 111–130 (with English summary)
ISSN: 1211–8796