Podrobnosti záznamu

Název
    Geochemical discrimination of metasedimentary sequences in the Krkonoše-Jizera Terrane (West Sudetes, Bohemian Massif): paleotectonic and stratigraphic constraints
Údaj o odpovědnosti
    John A. Winchester, František Patočka, Václav Kachlík, Mattyld Melzer, Claire Nawakowski, Quentin G. Crowley, Peter A. Floyd
Autor
    Crowley, Quentin G.
    Floyd, Peter A.
    Kachlík, Václav
    Melzer, Mattyld
    Nawakowski, Claire
    Patočka, František
    Winchester, John A.
Jazyk
    anglicky
Zdrojový dokument - seriál
    Geologica carpathica
Svazek/č.
    Vol. 54, no. 5
Strany
    p. 267-280
Rok
    2003
Poznámky
    8 obr., 2 tab., 3 s. bibl.
    il.
    Zkr. název ser.: Geol. carpath.
Předmětová skupina
    chemismus hornin
    Gondwana
    kontinentální okraj aktivní
    krkonošsko-jizerské krystalinikum
    litostratigrafie
    metasedimenty
    paleozoikum-spodní
    prekurzor
    proterozoikum
    sedimenty klastické
Geografické jméno
    ČR-Čechy
    Poniklá (Semily)
    Svoboda nad Úpou (Trutnov)
    Vrchlabí (Trutnov)
    Železný Brod (Jablonec nad Nisou)
Klíčové slovo
    Bohemian
    Constraints
    Discrimination
    Geochemical
    Krkonoše-Jizera
    Massif
    Metasedimentary
    Paleotectonic
    Sequences
    Stratigraphic
    Sudetes
    Terrane
    West
Abstrakt (anglicky)
   Metamorphosed clastic sediments from three lithostratigraphic groups (the low- to medium-grade Velká Úpa, and the low-grade Radčice and Poniklá Groups), exposed in a para-autochthonous to allochthonous unit of the Krkonoše-Jizera Terrane (KJT, West Sudetes), were studied in order to discover whether they are chemically discriminable. According to chemical features of the metasediments (e.g. lower Th/Sc and CeN/YbN ratios), the Velká Úpa Group is interpreted to be younger than the Neoproterozoic Machnin Group (of the KJT autochthonous unit) related to a Cadomian active continental margin setting. Metamorphosed clastics of the Poniklá and Radčice Groups proved to be chemically indistinguishable. As a result, these groups are herein combined within a single Vrchlabí Group of Cambrian-Ordovician to Silurian (+-Devonian?) age. Precursors of the Velka Upa and Vrchlabí Groups were apparently deposited on a passive margin of the peri-Gondwanan Saxothuringian microplate.
   The passive margin originated in Cambrian and Ordovician times during extension and rifting of the former (Cadomian) active continental margin of NW Gondwana. Comparison of the metasediment geochemistry, together with the stratigraphic and structural affinities within the KJT, allows the Velká Úpa and Vrchlabí Groups to be interpreted as broadly coeval: Cambrian to Silurian (+-Devonian?) in age. Deposition of the Vrchlabí Group was more distal and sourced by sediment derived from a more dissected area of the Cadomian basement (fossil active margin) as demonstrated by an enrichment in Hf, depletion in Sc and Cr, somewhat higher CeN/YbN values and slightly more pronounced negative anomalies of Eu. The geochemistry of the metasediments reflects the complex paleotectonic evolution of the West Sudetes that started with Cambrian-Ordovician intracontinental rifting and subsequent sea-floor spreading during marginal fragmentation of Gondwana
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    31. 3. 2008
Datum importu
    8. 8. 2012