Record details

    Geochemical discrimination of metasedimentary sequences in the Krkonoše-Jizera Terrane (West Sudetes, Bohemian Massif): paleotectonic and stratigraphic constraints
Statement of responsibility
    John A. Winchester, František Patočka, Václav Kachlík, Mattyld Melzer, Claire Nawakowski, Quentin G. Crowley, Peter A. Floyd
    Crowley, Quentin G.
    Floyd, Peter A.
    Kachlík, Václav
    Melzer, Mattyld
    Nawakowski, Claire
    Patočka, František
    Winchester, John A.
Source title - serial
    Geologica carpathica
    Vol. 54, no. 5
    p. 267-280
    8 obr., 2 tab., 3 s. bibl.
    Zkr. název ser.: Geol. carpath.
Subject group
    chemismus hornin
    kontinentální okraj aktivní
    krkonošsko-jizerské krystalinikum
    sedimenty klastické
Geographical name
    Poniklá (Semily)
    Svoboda nad Úpou (Trutnov)
    Vrchlabí (Trutnov)
    Železný Brod (Jablonec nad Nisou)
Abstract (in english)
   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
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    31. 3. 2008
Import date
    8. 8. 2012