Litofacie a facialni architektura miroslavskych slepencu (mladsi paleozoikum)

Coarse-grained clastic sediments overlay an eastern margin of the Miroslav Horst Crystalline Complex between Miroslavské Knínice and southern vicinity of Miroslav ( Fig. 1). This succession was designed as Miroslav Conglomerate, which is considered to be time equivalent to the lithologicaly similar Upper Carboniferous and Lower Permian conglomerates of the Boskovice Graben Basin (Kalášek 1956, Dudek 1963). The predominantly conglomeratic successions were studied recently in sedimentological point of view. Detail logging with lithofacies analysis and facies architecture studies were carried out. Six lithofacies have been discriminated and compared with the “standard” lithofacies of Miall (2006). The massive matrix supported (S1; Fig. 2A) and clasts supported (S2; Fig. 2B) conglomerates are prevailing lithofacies, which are comparable with Miall lithofacies Gmm and Gcm. The subhorizontally stratified clast-supported conglomerate (Fig. 2F) corresponds to Gh. Massive sandstones (P1; Fig. 3A) occur as lenticular intercalations within disorganised conglomerates banks. This lithofacies is probably equivalent to Sm. The ripple cross-bedded sandstones (P2; Fig. 3B) are also intercalated within conglomeratic banks or form thicker levels, where are accompanied by massive fine grained sandstones to siltstones (P3). These lithofacies correspond to the Miall’s facies codes Sr and Fm, respectively. Lithofacies S1, S2 and P1 are interpreted as gravity-flow deposits and S3, P2 and P3 are considered to be infill of braided channels. Depositional environment of the proximal alluvial fan with dominant debris flow deposition has been preliminary interpreted for the Miroslav Conglomerate.

References

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Kalášek, J. (1956): Zpráva o podrobném a přehledném mapování na generální mapě Brno. - Zpr. geol. Výzk. v Roce 1955, 79-82.

Matějovská, O. (1991): Geologická mapa ČR v měřítku 1 : 50 000, list 24-33 Moravský Krumlov. - Čes. geol. úst. Praha.

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Tomek, Č. (1990): The Miroslav horst - Moldanubian klippe or autochtonous massif? In: Minaříková, D. - Lobitzer, H., ed.: Thirty years of geological cooperation between Austria and Czechoslovakia, Chapt.: Structural geology and geophysics, 67-69. - Fed. Geol. Survey, Vienna - Czech Geol. Survey. Prague.