Record details

Title
    Compositional variation in tourmaline from tourmalinite and quartz segregations at Pernštejn near Nedvědice (Svratka Unit, western Moravia, Czech Republic)
Statement of responsibility
    Stanislav Houzar, Milan Novák, Julie B. Selway
Other titles
    Variace v chemickém složení turmalínu z turmalinitu a křemenných segregací od Pernštejna u Nedvědice (svratecké krystalinikum)
Author
    Houzar, Stanislav
    Novák, Milan, 1952-
    Selway, Julie B.
Language
    anglicky
Source title - serial
    Journal of the Czech Geological Society
Vol./nr.
    Vol. 43, no. 1-2
Pages
    p. 53-58
Year
    1998
Notes
    1 obr., 1 diagr., 1 tab., 19 bibl.
    České resumé
    Zkr. název ser.: J. Czech geol. Soc.
Subject group
    borosilikáty
    chemismus hornin
    cyklosilikáty
    křemen
    metamorfóza kontaktní
    podmínky P-T
    svratecké krystalinikum
    turmalín
    turmalinit
Geographical name
    ČR-Morava
    Pernštejn (Žďár nad Sázavou)
Keyword
    Compositional
    Czech
    Moravia
    Near
    Nedvědice
    Pernštejn
    Quartz
    Republic
    Segregations
    Svratka
    Tourmaline
    Tourmalinite
    Unit
    Variation
    Western
Abstract (in english)
   he Pernštejn Turmalinite is situated in the southern part of the Svratka Unit near the border with Moldanubicum. It underwent a retrogressive low-to-medium grade regional metamorphism which produced quartz segregations within the tourmalinite. Fine-grained tourmalinite dominantly consists of quartz and tourmalinite (dravite-schorl). The tourmaline is elongated, euhedral to subhedral grains are typically < 0.5 mm in size. Tourmaline (dravite-schorl) from quartz segregations forms euhedral grains, from 0.5 to 10 mm in size, locally associated with kyanite, andalusite, muscovite, apatite and accessory rutile. There is only a negligible difference between tourmaline from tourmaline and quartz segregations. Tourmaline of both paragenetic types is characterized by moderate to high vacancies in the X-site, up to 45 at.%, and moderate to high F contents varying from 0.32 to 0.56 apfu.
   It also exhibit Fe-Mg ratios and Al contents typical for tourmaline in metapelites and metapsammites with an Al-saturating phase (e.g., kyanite, andalusite). Formation of the quartz segregations with coarse-grained tourmaline and kyanite began during a retrogressive kyanite grade metamorphic event at P 3-4 kbar and T > 400-500°C through the kyanite-andalusite transition to the andalusite grade. The presence of tourmaline as the only ferro-magnesium mineral and the presence of Si-, Al- and Ti-saturating phases, i.e., qaurtz, kyanite/andalusite and rutile, respectively, buffered these elements during the mobilization process which produced the quartz segregations
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    18. 2. 2008
Import date
    8. 8. 2012