Mineralogie titanitových nodulí z biotitického granitu táborského plutonu (moldanubikum, kamenolom Dražičky u Tábora, střední Čechy)

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Acta Mus. Moraviae, Sci. Geol. 107 (2022), vydání 1, stránky 41-51
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Mineralogy of titanite-rich nodules from biotite granite of Tábor Pluton (Moldanubicum, Dražičky near Tábor quarry, Central Bohemia)

The elongated body of biotite granite with titanite-rich nodules is situated on the contact of amphibole-biotite and amphibole-pyroxene melasyenites of the Tábor pluton. Titanite-rich nodules are spherical, 1 to 3 cm in diameter and consists of a dark core (titanite + quartz + K-feldspar + plagioclase) surrounded by a leucocratic rim (quartz + K-feldspar + plagioclase ± phlogopite). Titanite, with an elevated Al (~ 0.07–0.11 apfu) and low F (0.039–0.069 apfu), forms subhedral poikilitic grains with abundant inclusions of euhedral to subhedral crystals of K-feldspar, plagioclase (An5–25) and anhedral quartz. The presence of titanite-rich nodules indicates intrusion of the felsic melt into the mafic system. This process led to the destabilization of biotite (amphibole) and the formation of titanium-rich melt, which was in corporated by the incoming felsic melt. The occurrence of isolated patches of poikilitic titanite rimmed by leucocratic rim indicates that Ti-rich melt flowed along with the felsic melt as a separate immiscible phase.

Kontakt:

David Buriánek, Czech Geological Survey, Leitnerova 22, 659 37 Brno, Czech Republic, e-mail: david.burianek@geology.cz
Stanislav Houzar, Department of Mineralogy and Petrography, Moravian Museum, Zelný trh 6, 659 37 Brno, Czech Republic

Citace
Buriánek, D., Houzar, S., 2022: Mineralogie titanitových nodulí z biotitického granitu táborského plutonu (moldanubikum, kamenolom Dražičky u Tábora, střední Čechy). – Acta Mus. Morav., Sci. Geol., 107, 1, 41–51 (with English summary)
ISSN: 1211–8796