Record details

Title
    Alkaline and carbonate-rich melt metasomatism and melting of subcontinental lithospheric mantle: Evidence from mantle xenoliths, NE Bavaria, Bohemian Massif
Author
    Ackerman, Lukáš
    Balogh, Kadosa
    Hegner, Ernst
    Magna, Tomáš
    Svojtka, Martin
    Špaček, Petr
    Ulrych, Jaromír
Language
    anglicky
Publication type
    článek v periodiku
Source title - serial
    Journal of Petrology
Vol./nr.
    Roč. 54, č. 12
Pages
    37
Year
    2013
Thesaurus term
    peridotite, xenolith, metasomatism, carbonate, alkali basalt, Sr isotopes, Nd isotopes, Li isotopes
Keyword
    Alkaline
    Bavaria
    Bohemian
    Carbonate-rich
    Evidence
    Lithospheric
    Mantle
    Massif
    Melt
    Melting
    Metasomatism
    NE
    Subcontinental
    Xenoliths
Abstract (in english)
   Peridotite xenoliths hosted by Cenozoic basanite lava flows (21.2-23.5 Ma) occur at several localities in the western continuation of the Ohře/Eger rift (Central European Volcanic Province) in NE Bavaria, Bohemian Massif. Detailed petrography, major and trace element compositions of whole-rock samples and selected mineral phases as well as Sr-Nd-Li isotopic compositions for a suite of mantle xenoliths from Zinst, Hirschentanz and Teichelberg document variable degrees of partial melting and metasomatism. Melting models involving whole-rock major element composition and Cr# of spinel yield ~6-30 % melting in the spinel stability field. Subsequent metasomatism by alkaline and carbonate-rich melts resulted in modal and cryptic metasomatism, expressed by the presence of carbonate-bearing silicate melt pockets with complex secondary mineral assemblages and by enrichment in light rare earth elements, Li, Rb, U, Pb, HFSE and P. The carbonate is most likely associated with fractionation of the
   Na-rich silicate melt. High P contents, variable, but low to negative d7Li values from +2.5 to -9.7? coupled with 87Sr/86Sr ratios between ~0.7032 and ~0.7041 may reflect significant contribution of recycled crustal material such as eclogite in the infiltrating melts responsible for metasomatism although Li isotopes may reflect kinetic modifications through diffusion. Trace element geochemistry of clinopyroxene, carbonate and melt suggests that clinopyroxene plays very important role in fractionation of the rare earth elements, high field strength elements and Sr, while carbonate does not host large quantities of incompatible trace elements except for Sr, Ba and, to a lesser extent Th and U.
Contributor
    Česká geologická služba
Contributor code
    ČGS (RIV)
Source format
    R
Import date
    15. 10. 2014