Podrobnosti záznamu

Název
    Compositional evolution of tourmaline in lepidolite-subtype pegmatites
Údaj o odpovědnosti
    Julie B. Selway, Milan Novák, Petr Černý, Frank C. Hawthorne
Další názvy
    Tourmaline 1997. International Symposium on Tourmaline (Variant.)
Autor
    Černý, Petr
    Hawthorne, Frank C.
    Novák, Milan, 1952-
    Selway, Julie B.
Jazyk
    anglicky
Zdrojový dokument - seriál
    European journal of mineralogy
Svazek/č.
    Vol. 11, no. 3
Strany
    p. 569-584
Rok
    1999
Poznámky
    9 obr., 1 tab., 3 s.bibl.
    Zkr. název ser.: Eur. J. Mineral.
Předmětová skupina
    chemismus minerálů
    dajka
    krystalizace
    moldanubikum strážecké
    pegmatit
    slídy
    turmalín
    zonálnost
Geografické jméno
    ČR-Morava
    Dobrá Voda (Žďár nad Sázavou)
    Dolní Bory (Žďár nad Sázavou)
    Kanada-Manitoba
    Laštovičky (Žďár nad Sázavou)
    Radkovice u Hrotovic (Třebíč)
    Rožná (Žďár nad Sázavou)
Klíčové slovo
    Compositional
    Evolution
    Lepidolite-subtype
    Pegmatites
    Tourmaline
Abstrakt (anglicky)
   Tourmaline from six pegmatites of the lepidolite-subtype was examined to determin compositional trends: symmetrically zoned Laštovičky, Dobrá Voda, Rožná, Dolní Bory and Radkovice dykes, Czech Republic, and relatively homogenous dykes at Red Cross Lake, Manitoba. The five symmetrically zoned lepidolite-subtype pegmatites contain the following zones from the outermost zone inward: (1) granitic zone, (2) graphic zone, (3) blocky K-feldspar zone, (4) albite zone, (5) lepidolite zone, (6) quartz core and (7) rare-to-absent small pockets. The crystallization sequence of tourmaline was determined from the characteristic composition of tourmaline for each pegmatite zone and from the compositional zoning within individual crystals. In granitic and outer alnite zones, black tourmaline ranges from foitite-schorl to schorl-foitite, and is associated with minor biotite close to the contact with the host rocks, and with abundant Fe-bearing muscovite.
   In the albite zones, dark blue and green elbaite-schorl is associated with pale greenish zellow Na-bearing muscovite. In the lepidolite zones, pink elbaite-rossmanite to rossmanite-elbaite occurs with purple lepidolite and minor pink and green lepidolite. Green (Fe, Mn)-bearing elbaite occurs in the quartz core at Rožná and is associated with cookeite in late pockets at Dobrá Voda and Dolní Bory. Late hydrothermal foitite occurs as terminations on zoned tourmaline crystals in pockets at Dobrá Voda. Based on paragenesis and textural relations, rossmanite- elbaite is the last tourmaline composition to crystallize in the Radkovice, elbaite-rossmanite is the last at Laštovičky and Red Cross Lake dykes, (Fe, Mn)-bearing elbaite is the last at Rožná and Dolní Bory, and foitite in the last at Dobrá Voda.
   Lepidolite-subtype pegmatites contain foitite as the most primitive composition in the outermost pegmatite zones, and rossmanite or (Fe, Mn)-bearing elbaite as the most fractionated compositions in the innermost pegmatite zones. In contrast, elbaite-subtype pegmatites in the literature contain Mg-rich schorl and either elbaite or rarely lidicoatite, respectively. Typically, tourmaline from lepidolite-subtype pegmatites is Ca- and Mn-poor (<0.03 apfu Ca, <0.30 apfu Mn), whereas tourmaline fom elbaite-subtype pegmatites is relatively Ca- and Mn-rich, commonly with up to 0.30 apfu Ca and locallu up to 1.1 apfu Mn. Schrol in lepidolite-subtype pegmatites is rich in X-site, whereas schorl in elbaite-subtype pegmatutes is Na rich. A negative correlation exists between Fe and Al+Li at the Y-site in tourmaline due to fractional crystallization of the evolving pegmatite-forming melt. The positive correlation between Na and F in tourmalie is due to crystal-chemical constraints.
   Sodium and Mn are preferentially partioned into tourmaline, and F is prefentially partitioned into lepidolite
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    15. 2. 2008
Datum importu
    8. 8. 2012