Podrobnosti záznamu

Název
    Stromatolite-like cherts in the Barrandian Upper Proterozoic: A review
Údaj o odpovědnosti
    Zdeněk Pouba, Bohdan Kříbek, Marta Pudilová
Autor
    Kříbek, Bohdan, 1946-
    Pouba, Zdeněk, 1922-
    Pudilová, Marta
Jazyk
    anglicky
Zdrojový dokument - seriál
    Věstník Českého geologického ústavu (Bulletin of the Czech Geological Survey)
Svazek/č.
    Vol. 75, no. 3
Strany
    p. 285-296
Rok
    2000
Poznámky
    4 obr., 12 fot., 3 tab.
    České resumé
    il.
    Obsahuje bibliografické odkazy
    Zkr. název ser.: Věst. Čes. geol. Úst. (Bull. Czech geol. Surv.)
Předmětová skupina
    Barrandien
    chemismus hornin
    izotopy stabilní
    proterozoikum
    rohovec křemitý
    sebcha
    sedimenty organické
    silicity
    Stromatolithi
    vzácné zeminy
Geografické jméno
    ČR-Čechy
    Kokšín (Klatovy)
    Mítov (Plzeň-jih)
Klíčové slovo
    Barrandian
    Cherts
    Proterozoic
    Review
    Stromatolite-like
    Upper
Abstrakt (anglicky)
   Microfossiliferous stromatolitic cherts morphologically similar to stromatolites of the Collenia type can be traced over a discontinuous horizon in the southeastern part of the Barrandian Upper Proterozoic (Neoproterozoic). Stromatolitic cherts occur in the form of lenticular bodies associated with volcanics, volcanoclatics, black cherts and with sediments of sabkha or black shale facies. The amount of organic carbon range between 0.3 and 0.4% in the dark laminae and is lower than 0.002% in light-coloured laminae. The isotope composition of organic carbon (Ű13C = -28 to -32 %, PDB) falls within the range of carbon isotope composition of Precambrian stromatolites. Trace amounts of isoprenoid hydrocarbons, phytane and pristane identified in the rock extract point to the phototrophic character of microorganisms in stromatolitic buildups.
   Isotope composition of oxygen of quartz in light (Ű18O = 20.1 to 20.8 %., SMOW) and dark (Ű18O = 20.1 to 20.9 %., SMOW) siliceous laminae is practically identical and indicates no significant temperature differences during their deposition. Organic carbon-rich laminae are enriched in K, P, V and U, organic matter-poor laminae have an increased content of Cr, Sb and other trace metals. The REE pattern in stromatolites resembles that of associated volcanics of OIT- and OIA-type and does not differ substantially from the REE pattern in hydrothermal, Cr-rich cherts, which commonly cement stromatolite fragments. It is suggested that stromatolites originated in an inter- or supratidal marine environment and were closely associated with active submarine or subaerial hydrothermal springs.
   The increased temperature of water and probably of CO2 resulted in increased activity of lagae and in periodical growth of lagae and/or bacterical mats on the surface of precipitated material deposited around or close to hydrothermal vents. At the present stage of knowledge, it is difficult to assess whether stromatolitic cherts originated from siliceous material
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    31. 3. 2008
Datum importu
    8. 8. 2012