Record details

Title
    Middle/Late Cambrian intracontinental rifting in the central West Sudetes, NE Bohemian Massif (Czech Republic): geochemistry and petrogenesis of the bimodal metavolcanic rocks
Statement of responsibility
    Jaroslav Dostal, František Patočka, Christian Pin
Author
    Dostal, Jaroslav
    Patočka, František
    Pin, Christian
Language
    anglicky
Source title - serial
    Geological journal
Vol./nr.
    Vol. 36
Pages
    p. 1-17
Year
    2001
Notes
    2 obr., 5 diagr., 3 s.bibl.
    il.
    Zkr. název ser.: Geol. J. (Chichester).
Subject group
    chemismus hornin
    geochemie izotopická
    Gondwana
    izotopy Nd
    izotopy Sm
    kambrium
    krkonošsko-jizerské krystalinikum
    magma bimodální
    metavulkanity
    petrogeneze
    vzácné zeminy
    zóna riftová
Geographical name
    ČR-Čechy
    Krkonoše-Rýchory
Keyword
    Bimodal
    Bohemian
    Cambrian
    Central
    Czech
    Geochemistry
    Intracontinental
    Massif
    Metavolcanic
    Middle/Late
    NE
    Petrogenesis
    Republic
    Rifting
    Rocks
    Sudetes
    West
Abstract (in english)
   The Early Palaeozoic East Krkonoše Complex (EKC) situated in the central West Sudetes, NE Bohemia Massif, is a volcanosedimentary suite containing abundant mafic and felsic volcanics metamorphosed to greenschist facies. The trace element distribution patterns and Nd isotope signatures (E Nd 500 = +3.1 to +6.6) of the metabasites (metabasalts) indicate that they may be related to a rising mantle diapir associated with intracontinental rifting. At the early stage, limited melting of an upwelling asthenosphere produced alkali basalts and enriched tholeiites which compositionally resemble oceanic island basalts. A later stage of rifting with larger degrees of melting at shallower depths generated tholeiitic basalts with E-MORB to N-MORB characteristics.
   The values of (87Sr/86Sr)i = 0.706 and E Nd 500 = -5˝1 of porphyroids (metarhyolites) as well as the lack of rocks with intermeadiate compositions suggest that the felsic rocks were formed by a partial melting event of continental crust triggered by mantle melts. The geochemistry of the EKC bimodal metavolcanics and their association with abundant terrigenous metasediments suggest that the felsic-mafic volcanic suite was generated during intracontinental rifting. This process, widespread in Western and central Europe during the Early Palaeozoic, is evidence of large-scale fragmentation of the northern margin of the Gondwana supercontinent
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    15. 8. 2007
Import date
    8. 8. 2012