Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Biotite of regional-metamorphic origin in metapelites of the Železný Brod Crystalline Unit
Abstract
The Železný Brod Crystalline Unit in northern-Bohemia is a MP/LT metamorphic terrane with local HP relics. The sheet silicates of its metapelites are represented by the standard assemblage sericite-chlorite, no higher tempered minerals as biotite, garnet or staurolite being signalised here. All previous authors have ranged these rocks unanimously into the chlorite zone. The new discovery of the presence of biotite in the roofing phyllites of Jirkov near Železný Brod amends this conception proving that biotite zone was attained in some parts of the Unit. Assuming the pressure of 450 MPa, the temperature of 460°C or locally even slightly higher can be taken into account as the peak value for the regional metamorphism in the Železný Brod area.
