Dumortierite and tourmaline from abyssal pegmatites at Vémyslice near Moravský Krumlov, Gföhl unit, MoldanubicumArticle PDF
Dumortierite and tourmaline from abyssal pegmatites at Vémyslice near Moravský Krumlov, Gföhl unit, Moldanubicum
Abyssal pegmatites with dumortierite and tourmaline cut biotite-sillimanite gneiss at Vémyslice near Moravský Krumlov, Gföhl Unit. Pegmatites are highly peraluminous, characterized by presence of dumortierite and sillimanite, and tourmaline and andalusite, respectively. Dumortierite is enriched in As – 0.22 apfu and Ti – 0.20 apfu. Tourmaline of a schorl-oxy-schorl-foitite-dravite solid solution shows high Al in the T-site. The primary assemblage K-feldspar+andalusite in tourmaline-bearing pegmatite suggests low pressure about 3 kbar or less and temperature about 600°C; dumortierite-bearing pegmatite formed at higher temperature and/or pressure. Absence of primary muscovite differs the abyssal pegmatites at Vémyslice from similar abyssal pegmatites with dumortierite, olenite, schorl, sillimanite, kyanite and primary muscovite of the Kutná Hora region.
Jan Cempírek, Milan Novák, Institute of Geological Sciences, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic, e-mail: email@example.com