PhD. thesis - Univerzita Karlova

2.1. Pre-Cretaceous geology of the studied area
The studied area is located in the southern part of the CWC and comprises three major
lithological and tectonometamorphic units (Fig. 1). From the north to the south and from the
bottom to the top they are 1) Variscan crystalline basement (Vepor Unit) with Late Paleozoic
and Mesozoic cover sequences, 2) Early to Late Paleozoic, basinal, mostly low grade turbiditic
sequences (Gemer Unit), and 3) Mesozoic accretionary wedge containing blueschist facies
relics overlain by 4) flat non-metamorphosed Silica nappe.
2.1.1. Variscan crystalline basement - the Vepor Unit. The crustal rocks of the Vepor
basement are composed of two contrasting Variscan metamorphic domains exhibiting
pre-Alpine thrust tectonics. Structurally lower domain, generally dipping to the north, is
composed of medium-grade schists exhibiting peak PT conditions in Ky-St micaschists
corresponding to max. 10 kbars and 550°-600°C [Korikovskij et al., 1989; Méres and Hovorka,
1991]. The classic Barrow type metamorphic zonation is difficult to establish due to the Alpine
greenschist facies overprint but in the eastern part of the Vepor basement (Čierna Hora Mts),
a metamorphic zonation ranging from biotite zone in the south to staurolite zone in the north is
documented [Jacko et al., 1990; Korikovskij et al., 1990]. Structurally higher crystalline unit is
represented by a domain of heterogeneous para- and ortho-derived migmatites intruded by
porphyritic to medium-grained peraluminous granites. The Variscan age of metamorphism is
docummented by Th-U-Pb dating of monazite [370-350 Ma, Janák et al., 2001a] and by
sporadically preserved 40 Ar/ 39 Ar cooling ages ranging from 358 to 312 Ma [Dallmeyer et al.,
1996]. High-grade fabrics represented by compositional layering and stromatitic banding in
migmatites are dipping either to the NW or to the N under steep to medium angles. Peak
temperature conditions yield 680 - 730°C at pressures of 4 - 6 kbars (Fig. 2) [Siman et al., 1996].
These PT conditions most likely correspond to late exhumation and decompression melting.
This is deduced from other parts of West Carpathians where relics of high-pressure assemblages
preserved in similar types of migmatites were found [Hovorka and Méres, 1989; Janák et al.,
1996].
The southern Vepor Variscan crystalline basement is unconformably covered by Late
Carboniferous (Stephanian) sandstones and shales [Planderová and Vozárová, 1978]. These
metasediments were intruded by granitoids that were responsible for contact metamorphism
ranging from biotite to cordierite zones. Contact metamorphic conditions of 500°C and 2 kbars
were established by Vozárová [1990]. This author also suggests that contact metamorphism
overprinted regional greenschist facies assemblages of Carboniferous metasediments. The
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