Podrobnosti záznamu

Název
    The "white beds" - a fossil caliche of the Barrandian area: its origin and paleoenvironmental significance
Údaj o odpovědnosti
    Václav Suchý
Další názvy
    Bílé vrstvy Barrandienu - fosilní caliche: jejich původ a význam pro rekonstrukci paleoprostředí
Autor
    Suchý, Václav
Jazyk
    anglicky
Zdrojový dokument - seriál
    Journal of the Czech Geological Society
Svazek/č.
    Vol. 47, no. 1-2
Strany
    p. 45-54
Rok
    2002
Poznámky
    3 obr., 12 fot., 37 bibl.
    České resumé
    il.
    Zkr. název ser.: J. Czech geol. Soc.
Předmětová skupina
    Barrandien
    caliche
    diageneze
    kalkrusta
    paleoprostředí
    paleozoikum-svrchní
    půda fosilní
    vápenec
Geografické jméno
    ČR-Čechy
Klíčové slovo
    Area
    Barrandian
    Beds
    Caliche
    Fossil
    Origin
    Paleoenvironmental
    Significance
    White
Abstrakt (anglicky)
   So-called "white beds" - a snowy white to rusty yellow, sandy to chalky wweathered carbonate alteration horizons locally developed over the lower Paleozoic limestones - are interpreted in terms of fossil carbonate soil (caliche, calcrete). A typical caliche sequence affects as much as 6-8 meters of the limestone host and develops gradually from a transitional zone exhibiting largely, dissolution phenomena. These altered limestones grade upwards into a chalky zone of completely disintegrated carbonate that, in turn, gives way to a zone of coalecing carbonate nodules commonly developed below the recent soil cover. Microscopic phenomena observed in the carbonates closely match those known from both recent and ancient caliche elsewhere, and include calcite nodules, circum-granular cracking, rhizoliths, Microcodium, alveolar-septal structures, tangecial needle-fiber calcite cements and floating calcite rhombs.
   Following the paleosoil formation, some of the caliche deposits were subject re deposition and/or collapse into the paleorelief depressions and introduction of alluvial gravels and fine silicicalstic material into the caliche matrix. The age of the caliche is not known. Assuming that the formation of caliche paleosoil requires the conditions of long-lasting geomorphologic stability and arid to semi-arid climatic setting with low annual rainfall, the alteration can be tentaviley attributed to a protacted period of peneplenization and reduced deposition that occurred in the Bohemian Massif during the Mesozoic-Tertiary era. Alternatively, the caliche facies may have also developed in response to Pliocene-Pleistocene climatic fluctuations
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    30. 5. 2007
Datum importu
    8. 8. 2012