Polyphase deformation of the Variscan accretionary wedge: an example from the southern part of the Moravian Karst (Bohemian Massif, Czech Republic)

Abstract

The presence of two different coeval pre-flysch carbonate facies juxtaposed in numerous profiles in the southern part of the Moravian Karst proves that the Variscan nappe tectonics affected the pre-flysch basement of the main Culmian flysch nappes. Two main thrust events were recognized: (1) a ‘thin-skinned’ event, during which two sedimentary facies were juxtaposed along bedding sub-parallel thrusts, and (2) a ‘thick-skinned’ event, which generated younger thrusts oblique to bedding, involved crystalline rocks of the Brno Massif, and resulted in refolding of the older thrusts.

Kinematic evolution and structural styles of fold-and-thrust belts

“…Mingramm et al 1979;Allmendinger et al 1983). (c) Superimposed in the same region but developed during different times, such as the Bohemian Massif where an initial thin-skinned event is followed by a thick-skinned phase in which thrusts involve crystalline rocks and cross-cut older structures (Rez et al 2011). Some shortening-dominated regions formed by reactivation of inherited structures include elements from both FAT belts (thin-skinned) and basementinvolved belts (thick-skinned).…”

Devonian Sedimentary Rocks Tectonically Incorporated Into the Brno Massif, Eastern Margin of the Bohemian Massif

“…6c). Considering similar folded boundaries between the Brno Massif and the Devonian rocks (Melichar, Kalvoda 1997;Rez et al 2011), where axial surfaces of large drag folds dip to the west, the anticline fold seems to be more plausible.…”

“…The Veveří castle zone (or Čebínka zone) consists of small discontinuous sheets, which have been dislocated by the marginal fault zone of the Boskovice furrow that complicates its interpretation (Bábek et al 1995;Špaček et al 2002). On the other hand, brittle-ductile structures associated with thrust shear zones and drag folds were discovered at the eastern margin of the Brno Massif in the Němčice belt (Melichar, Kalvoda 1997) as well as in southern part of the Moravian Karst (Rez et al 2011).…”

The first lower Viséan trilobite association from limestone facies of the Moravian Karst and its relation to the sedimentary environment (Líšeň Formation, Czech Republic)

“…Two main limestone lithologies can be distinguished in this interval: 1) dark grey to black platy limestones, locally with thin shale intercalations and cherts, mainly representing calciturbidites, known as HádyŘíčka Limestone, and 2) medium to dark grey, reddish, greenish or locally variegated, commonly nodular, bedded to massive limestones known as Křtiny Limestone, which are often supposed to represent mainly hemipelagites and muddy calciturbidites (e.g. Kalvoda et al 2008Kalvoda et al , 2015Rez et al 2011). During the upper Tournaisian and lower Viséan, the carbonate sediments of the Líšeň Formation were laterally and vertically replaced by the Březina Formation, which is represented mainly by greenish, reddish or brownish aleuropelitic shales, locally alternating with limestone layers (Kalvoda et al 2010).…”

“…The Březina Formation is considered to reflect a transitional phase between a "preflysch" Moravian Karst "platform" development, represented mainly by limestones and flysch of the siliciclastic "Culm facies" characterised by overlying successions of the Rozstání and Myslejovice formations (e.g. Kalvoda et al 2010, Rez et al 2011.…”