Podrobnosti záznamu

    Genetické typy červených sedimentů (red beds) v limnickém svrchním paleozoiku Českého masivu
Údaj o odpovědnosti
    Jiří Pešek, Vladimír Skoček
Další názvy
    Upper Paleozoic red beds in continental basins of the Bohemian Massif
    Pešek, Jiří, 1936-
    Skoček, Vladimír, 1934-
Zdrojový dokument - seriál
    Sborník Západočeského muzea v Plzni. Příroda
    Roč. 95
    s. 72
    39 obr., 13 tab., 6 obr., 4 s.bibl. + 6
    Anglické resumé
    Zkr. název ser.: Sbor. Západočes. Muz. (Plzeň), Přír.
Předmětová skupina
    prvky stopové
    red beds
    sedimentace fluviální
    svrchní paleozoikum Českého masivu
    vlastnosti magnetické
    železo trojmocné
Geografické jméno
    Česká republika
Klíčové slovo
Abstrakt (anglicky)
   Three types of genetically different red bed are present within the continental Upper Paleozoic basins of the Czech Republic: a) alluvial (alluvial fan + alluvial plain and deltaic topsets), b) lacustrine (ephemeral lakes, marginal parts of perennial lakes with fluctuating level), c) oxidized former grey or uncoloured sediments. The red bed distribution shows certain fluctuations both in area and time. The domination of red beds characterizes Stephanian A and Permian intervals whereas they are nearly totally absent in Stephanian B and negligibly present in Westphalian C, D, Cantabrian. From the study of pigmentation it is concluded that the source areas in all intervals yielded mostly terrigenous material poor in organics, containing Fe in the form of hydrated and dehydrated oxides, clastic minerals and rock fragments. The mixing of such material with organic matter in the course of transportion are the temporary and final deposition led to origin of grey beds.
   On the other hand absence or an insufficient amount of organic matter was the prerequisite of the final red coloration. The production of red beds on one side and preservation of organic matter in sediments on the other side reflect the generally changing climatic conditions within the area (increasing aridity from the Westhalian C to Permian). The detailed study has revelaed that in almost every interval during basin filling both red and grey sediments were simultaneously deposited in various proportions. The coal bearing intervals incorporate red units which indicate margin of the source area or elevated ridges within the sedimentary basin. The grey or black equivalents within the red lithostratigraphic units indicate perhumid environment connected either with a locally elevated ground water level or a lacustrine regime. The coloration of sediments indicates their diagenetic and later history.
   The relationship between color and the morphology of the pigmenting hematite has been studied. The color value depends also on the amount of clay fraction, the age of the unit and its location within the sedimentary basin. The reduction of Fe3+ and its subsequent leaching or conversion into Fe2+ authigenic minerals affected red sediment or their unstabilized equivalents in various stages of diagenesis. The decisive role of active organic matter was enhanced in places by microbial activity and mobilization of metals. The leached, green, spherical reduction spots, common in sediments of the Stephanian and Permian age indicate the catalytic role of V, U, Cu, Pb in the migration and reduction of Fe3+. These spots originated in the early diagenetic stage of red mudstones exposed to deep changes of pore water chemistry due to fluctuating humidity and temperature.
   The variability of Al and Ti amounts in the hematite crystalline lattice, was used as evidence of clastic or authigenic hematite formed from hydrated oxides or other minerals. The study of the remanent magnetization and its ori
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
Datum vložení
    18. 2. 2008
Datum importu
    8. 8. 2012