Podrobnosti záznamu

    Neoproterozoic sedimentary carbonates and their silicified equivalents: Barrandian, Czech Republic
Údaj o odpovědnosti
    Vladimír Skoček, Zdeněk Pouba
    Pouba, Zdeněk, 1922-
    Skoček, Vladimír, 1934-
Zdrojový dokument - seriál
    Věstník Českého geologického ústavu (Bulletin of the Czech Geological Survey)
    Vol. 75, no. 3
    p. 241-260
    4 obr., 19 fot., 1 tab.
    České resumé
    Obsahuje bibliografické odkazy
    Zkr. název ser.: Věst. Čes. geol. Úst. (Bull. Czech geol. Surv.)
Předmětová skupina
    horniny karbonátové
    prostředí hypersalinní
    sedimentace detritická
    sedimenty karbonátové
    struktura oolitická
Geografické jméno
Klíčové slovo
Abstrakt (anglicky)
   The Neoproterozoic sequence incorporates sedimentary limestones and dolomites in thin layers and lenses. Oolitic, pisolitic, stromatolitic and micritic limestones with an admixture of various allochemical particles were distinguished in addition to breccias. Coated grains occur as two distinctly different types. Microoids (diam. below 0.3 mm) and pisoids (diam. 3-6 mm) are considered a product of repeated growth in agitated water. Volcanic accretionary lapilli are mostly small (diam. below 2 mm) carbonized bodies with poorly developed concentric texture. Limestones with unusual, characteristic crystalline texture are the result of the replacement of chemically unstable layers of evaporites (sulpfates). Arenites and greywackes with carbonate cement and shales with carbonate lenses are the products of diagenetic carbonate redistribution. The sedimentary carbonates differ from carbonized volcanogenic rocks by relict textures, elevated amounts of Sr and typical negative 18O/16O ratios.
   The similarity of structurea and textures,, between sedimentary carbonates and some siliceous rocks evokes the suspicion that some cherts in the sequence are of replacement origin. This is evidenced by quartzose pseudomorphs of dolomite rhombs and by the presence of silicified sulfate aggregates in them. The small size of stromatolitic buil-up indicates a limited extent of favourable circumstances for the growth of algal mats. The areal aasociation of carbonates with shales, siliciclastics, volcanic and volcaniclastic rocks shows that the majority of detrial carbonate were deposited from gravity current initiated at the edges of volcanic islands
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
Datum vložení
    31. 3. 2008
Datum importu
    8. 8. 2012