Stratigraphic reconstruction of tectonically disturbed carbonate sequences along the western margin of the Brno batholith: a need of multidisciplinary approach

 

Authors: Špaček P, Kalvoda J, Hladil J, Melichar R

Published in: Bulletin of Geosciences, volume 77, issue 3; pages: 201 - 215; Received 17 December 2001; Accepted in revised form 20 March 2002;

Keywords: Moravo-Silesian pre-Variscan Palaeozoic, Brno batholith, Moravian Karst,

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Abstract

Extremely complicated evolution of the western margin of the Brno batholith resulted in a poor preservation of the Devonian and Lower Carboniferous in several fragments of a different stratigraphic range and deformational degree. The research of geological development has shown that sedimentological interpretations of such tectonically disturbed carbonate sequence require a multidisciplinary approach. After describing the most important transformations of limestone microfabric during the low-temperature ductile deformation, new data on biostratigraphy and facies of these relics of sedimentary successions are presented. The outcrop data are supplemented with facies and biostratigraphic information on eroded levels of carbonates that come from the limestone pebbles in the adjacent Permian alluvial fans of the Rokytná Member conglomerate.
Three stratigraphic horizons are present, distinctly separated from one another by two gaps without any lithological content:
1. Eifelian to lowermost Givetian reef limestones, which can be paralleled to the Čelechovice Cycle of the Moravian Karst Development.
2a. A thick succession of Middle Givetian to Lower Frasnian reef limestones with the development analogous to the Macocha Formation of the Moravian Karst.
2b. Calciturbidites overlying succession 2a in the Chudčice-Hůrka-Dálky area, in which Lower Frasnian conodont assemblages were identified.
3. Uppermost Famennian to Middle Viséan complex of limestones facially close to the Konice Palaeozoic or to the southern Moravian Karst limestones.
In spite of the good correspondence of the limestones in horizons 1 and 2a with the Moravian Karst Development, the Lower Frasnian calciturbidites (horizon 2b) have not been reported from other typical exposures of the Macocha Formation in Moravia yet; their relation to Moravian Karst Development is thus not clear.