Turmalinity jižní části svrateckého krystalinikaČlánek v PDF
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 X◻YAlWOH XNa-1Y (Mg,Fe)-1WF-1 and YFeYMg-1.
Renata Čopjaková, Radek Škoda, Institute of Geological Sciences, Masaryk University and Czech Geological Survey, Kotlářská 2, 611 37 Brno, Czech Republic, e-mail: email@example.com, firstname.lastname@example.org
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: email@example.com