Burial and uplift history of the Palaeozoic Flysch in the Variscan foreland basin (SE Bohemian Massif, Czech Republic)

Abstract

Abstract. Organic and clay indicators were measured to characterise the burial and thermal history of Devonian through Upper Carboniferous siliciclastic and carbonate rocks in the Rheno-Hercynian zone of the Variscan orogeny in Moravia (eastern Czech Republic). The very low-grade metamorphism is documented by the illite crystallinity (IC) and vitrinite reflectance (R r ) in the inner part of the thrust and fold belt in the NNW. Application of forward thermal modelling suggests maximum palaeo-temperature of 240-360 • C and burial depth of 4-9 km. In the Variscan foreland in the SSE the IC and R r values are typical of diagenetic conditions with maximum palaeo-temperature of 80-130 • C. The distribution of both clay and organic maturity parameters is interpreted as a result of pre-and syn-tectonic thermal exposure of the rocks due to burial by a wedge-shaped body of thrust sheets thinning towards the Variscan foreland where only sedimentary burial was effective. The amount of uplift and denudation increases from the foreland to the RhenoHercynian thin-skinned thrust and fold belt.

Lateral development of coalification in the Czech part of the Upper Silesian Coal Basin and its connection with gas deposits

“…(2008). As follows from areal variations in rank of coal and fluctuation in its vertical development it is apparent that tectonics (Petránek and Dopita, 1955), influx of heat in front of an orogenic front or close to magmatic intrusions (Dvořák and Wolf, 1979;Francu et al 2002) and even fossil weathering (Klika et al, 2004) have played important roles in the process of coalification. The extent and effects of these processes are presently being studied.…”

U-Pb zircon age of the Krásné Loučky tuffite: the dating of Visean flysch in the Moravo-Silesian Paleozoic Basin (Rhenohercynian Zone, Czech Republic)

“…It is also dif fi cult to imag ine that dur ing tectonism the sur face ma te rial was al most im me di ately bur ied to depths of 4-10 km, which is the es ti mated thick ness of the eroded de pos its (cf. Francu et al, 2002).…”

“…1). Their to tal thick ness prob a bly reaches 7.5 to 12 km (Kumpera and Martinec, 1995;Mazur et al, 2006), but pre cise thick nesses cannot be given be cause of strong tec tonic re work ing in the Variscan accretionary wedge (Grygar and Vavro, 1995;Kumpera and Martinec, 1995), as well as in tense post-Car bon if er ous and proba bly also Car bon if er ous ero sion in those parts close to the orogenic front (Francu et al, 2002). Only lim ited in for ma tion has been ob tained from a few bore holes.…”

Coal-bearing capacity of the Petřkovice Member (Ostrava Formation, Serpukhovian, Mississippian) of the Upper Silesian Basin (Czech Republic and Poland)

“…Car bon if er ous sed i men ta tion be gan with pre-orogenic car bonates. The ef fect of the Variscan orog eny is rec og niz able in a sequence of ma rine siliciclastic flysch de pos its (Culm fa cies) with pre-ero sional thick nesses of up to 11 km (Francu et al, 2002). Sed i men ta tion con tin ued through the coal-bear ing paralic and later terrigenous molasse be fore and also af ter the fi nal collapse of the orogen and ter mi na tion of the as so ci ated tec tonic events .…”