Record details

Title
    The Ševětín astrobleme - product of an impact, tectonic style or cryptovolcanism?
Statement of responsibility
    Lubomír Kopecký
Other titles
    Ševětínský astroblém
Author
    Kopecký, Lubomír
Language
    anglicky
Source title - serial
    Krystalinikum
Vol./nr.
    Vol. 23
Pages
    p. 59-82
Year
    1997
Notes
    8 obr., 1 fot., 3 s.bibl.
    České resumé
    Zkr. název ser.: Krystalinikum
Subject group
    brekcie
    diskuse
    impaktní struktura
    karbonatit
    kryptogenní jevy
    křída-svrchní
    metamorfóza šoková
    moldanubikum jižních a jihovýchodních Čech
    třeboňská pánev
    vulkanismus
    zlom
Geographical name
    ČR-Čechy
    Kanada-Ontario
    Rusko-Sibiř
    SRN
    Ševětín (České Budějovice)
Keyword
    Astrobleme
    Cryptovolcanism
    Impact
    Product
    Style
    Ševětín
    Tectonic
Abstract (in english)
   Vrána's impact model of petrological, geological and geophysical data for the "Ševetín astrobleme" contradicts the true origin of the described features. This critical article is intended to evaluate the genetic importance of the described phenomena which include breccias with shock features, impact melts, pseudotachylite, shatter cones, rocks containing shock-affected quartz and a gravimetric minimum. It also presents evidence of non-impact origin of shock metamorphism phenomena which are the major argument for the impact model for the Ševětín structure. Vrána's explanation of the above mentioned phenomena of impact derivation was found to be unreliable. Contrary to Vrána's interpretation, these phenomena are considered rather an evidence of cryptovolcanic origin of the Ševětín structure. The major argument rejecting the impact model is the observation of Codier et al.
   revealing that the deformed quartz in the Ševětín is a product of tectonic style, and the complex texture of the so-called "impact breccias" which provides of their prolonged development. The Drahošice fault is interpreted as a vent for brecias ascending from an inferred subsurface cryptovolcanic structure. Using the analogy of the Stophenheim dome (Germany) with the Ševetín structure, the latter can be interpreted as a relict of a cryptovolcanic dome. Purely tectonic origin of structural deformations in quartz is questionable due to the diversity of its host rocks
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    20. 2. 2008
Import date
    8. 8. 2012