Podrobnosti záznamu

    Late-Collisional Granites in the Variscan Erzgebirge, Germany
Údaj o odpovědnosti
    Hans-Jürgen Förster, Gerhard Tischendorf, Robert B. Trumbull, B. Gottesmann
    Förster, Hans-Jürgen, 1948-
    Gottesmann, B.
    Tischendorf, Gerhard
    Trumbull, Robert B.
Zdrojový dokument - seriál
    Journal of petrology
    Vol. 40, no. 11
    p. 1613-1645
    9 obr., 14 tab., 4 s.bibl.
    Zkr. název ser.: J. Petrology
Předmětová skupina
    chemismus hornin
    chemismus minerálů
    geochemie izotopická
    krušnohorský pluton
    minerály akcesorické
Geografické jméno
    Krušné hory
Klíčové slovo
Abstrakt (anglicky)
   The late-collisional Erzgebirge granites (&325-318 Ma) were emplaced at shallow crustal levels in the Variscan metamorphic basement shortly after large-scale extension caused by orogenic collapse. These granites comprise mildly peraluminous transitional I-S-types and strongly peraluminous S-type rocks, which can be subdivided into three major groups: low-F biotite granites; low-f two-mica granites; and high-F, high-P2O5 Li-mica granites. The highest degree of differentiation is reached in the Li-mica granites, which exhibit strongly elevated concentrations of P, F, Li, Rb, Cs, Ta, Sn, W and U; but very low Ti, Mg, Co, Ni, Sr, Ba, Y, Zr, Hf, Th and rare earth elements. Crystal-melt fractionation is the dominant process controlling the bulk composition of all group of granites.
   However, metasomatic processes involving late-stage residual melts and high-T orthomagmatic fluids became increasingly more important in highly evolved units and have modified the abundances of mobile elements (P, F, Li, Rb, Cs, Ba, Sr) in the Li-mica granites particularly. Isotopic and geochemical characteristics suggest that the three granite groups cannot be derived from a common precursor magma. Their discrete compositions are source related, and are attributed to melting of quartzo-feldspathic and pelitic crustal lithologies in different proportions. Granites are common in the central European variscides, but the Erzgebirge is unusual for the predominance of evolved Li-mica granites associated with economically important Sn, W and U deposits.
   The abundance of Li-mica granites is attributed to a combination of favourable factors: (1) low degrees of anatectic melting of crustal protoliths; (2) wide distribution of fertile lithologies rich in large-ion lithophile elements and ore elements; (3) extended magmatic differentiation by crystalmelt fractionation and subsequent autometasomatism
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
Datum vložení
    28. 3. 2008
Datum importu
    8. 8. 2012