Record details

Title
    The juxtaposition of eclogite and mid-crustal rocks in the Orlica-Snieznik Dome, Bohemian Massif
Author
    Bollinger, C.
    Chopin, F.
    Lexa, Ondrej
    Martelat, J.E.
    Pitra, Pavel
    Schulmann, Karel
    Skrzypek, Etienne
    Štípská, Pavla
    Žáčková, Eliška
Language
    anglicky
Publication type
    článek v periodiku
Source title - serial
    Journal of Metamorphic Geology
Vol./nr.
    Roč. 30, č. 2
Pages
    22
Year
    2012
Thesaurus term
    Bohemian Massif, crustal-scale folding, eclogite, exhumation, pseudosection modelling
Keyword
    Bohemian
    Dome
    Eclogite
    Juxtaposition
    Massif
    Mid-crustal
    Orlica-Snieznik
    Rocks
Abstract (in english)
   Eclogite, orthogneiss and grt-st metapelite occur in a 5 km long profile in the area of Miedzygorze in the Orlica-Snieznik dome. Petrographic observations and mineral equilibria modelling, in the context of structural work, are used to document the close juxtaposition of HP and MP rocks. The structural succession in all lithologies shows an early shallow-dipping fabric,that is folded by upright folds and overprinted by a heterogeneously developed subvertical foliation. Late recumbent folds associated with a weak shallowdipping axial-plane cleavage, occur locally. The S1 in the eclogite is defined by alternation of grt-rich and omp-rich layers with oriented mu and accessory ky, zo, rt and qtz, indicating conditions of 19-22 kbar and 700-750C. The assemblage in the retrograde S2 is formed by amp,plg, bt and rt surrounded by ilm and ttn, compatible with decompression and cooling from 9 kbar and 730C to 5-6 kbar and 600-650C. The S3 contains in addition domains with ab, chl, Kfs and mgt in
   dicating cooling to greenschist facies conditions. The metapelites are composed of grt, st, mu, bt, qtz, ilm and chl. Chemical zoning of garnet cores that contain straight ilm and st inclusion trails oriented perpendicular to the external S2 indicates prograde growth, from 5 kbar/520C to 7 kbar/610C, during the formation of the S1. Inclusion trails parallel with the S2 fabric at garnet and staurolite rims are interpreted to be a continuation of the prograde path to 7.5/630C in the S2. Matrix chlorite parallel to the S2 foliation indicates that the subvertical fabric was still active below 550C. The axial planar S2 developed during upright folding are associated with retrogression of the eclogite under amphibolite facies conditions, and with prograde evolution in the metapelites, associated with their juxtaposition. The shared part of the eclogite and metapelite P-T paths during the development of the subvertical fabric reflects their exhumation together.
Contributor
    Česká geologická služba
Contributor code
    ČGS (RIV)
Source format
    R
Import date
    15. 10. 2014