Geochemical specialization of the tin-bearing granitoid massifs of NW Bohemia

Abstract

The geochemistry of Hercynian tin-bearing granitoid massifs of the Krugne hory Mts. (Erzgebirge), Slavkovsk~ les Forest (Kaiserwald) and Smr6iny (eastern Fichtelgebirge) is compared by statistical processing of 270 analyses including a wide spectrum of major and trace elements. Seven different types of granites are distinguished. Out of these, five types represent the successive differentiation of the largest massif of NW Bohemia: the Karlovy Vary (Karlsbad) massif. This comprises strongly differentiated peraluminous granites evolving towards extreme Li-Rb-Cs-F-and Sn-enrichment in the youngest members, which are albite-topaz-zinwaldite "lithium" granites. The sixth and seventh types are different from the former by their location in the eastern Krugne hory and tectonic setting, and they display geochemical features of anorogenic granites: they are metaluminous albite-zinwaldite granites with marked enrichment of Nb, Y, and HREE in addition to Li, Rb, Cs, F and Sn, indicating contamination by sub-crustal material. Sn-W mineralizations, including flat peri-contact greisen bodies, steep greisen veins and tourmalinized phyllites, are all intimately associated with the most strongly differentiated granites -the Li-granite and the Cinovec-granite respectively.The Krugne hory rots. (Erzgebirge) and Slavkovsk) les Forest [Kaiserwald] form the classical central European mining district of tin (and tungsten) from greisen deposits in granite massifs of Hercynian age. These massifs are strongly differentiated into several successive intrusive phases. For this reason they are perfectly suited for studies of the relationship of granite evolution and Sn-W mineralization.Until today the area most attractive to geologists has been the largest granite massif of the area: the Karlovy Vary (Karlsbad) massif. Here, two major granite types were differentiated more than one hundred years ago (Laube 1876): the older, unmineralized "mountain granite" (Gebirgsgranit), nowadays often termed the "older intrusive complex" (330-320 Ma), and the younger, orebearing "Krugn6 hory granite" (Erzgebirgsgranit) now classified as the "younger intrusive complex" (305 295 Ma, ages after Tischendorf et al. 1989). Transitional granites connecting the two main types, were discovered in the Slavkovsky les Forest by Fiala (1968). Previous investigations of granite differentiation in NW Bohemia were mainly based on petrographically distinguished granite types (Lange et al. 1972;Baumann et al. 1974; ~temprok 1987;Tischendorf et al. 1989). There is a certain deficiency in this aproach as the granites of NW Bohemia are mineralogically relatively monotonous, but texturally very diversified. Due to this reason, an objective classification of the evolutionary phases, including a regional parallelization of the different massif s, was practically impossible so we have selected chemical data as a more objective way of evaluating the evolution of these granites. This is not only a theoretical problem, but also extremely important in order to improve the understandi...

Nearly contemporaneous evolution of the A- and S-type fractionated granites in the Krušné hory/Erzgebirge Mts., Central Europe

“…From then, the theory of autometasomatism significantly influenced the genetic interpretation of fractionated granites albite-zinnwaldite-topaz alkali feldspar leucogranites (Krudum, Nejdek-Eibenstock, Cínovec, Krupka). This classification and relative geological age of both complexes have repeatedly been confirmed both by field mapping and by petrographical, mineralogical and chemical data (Breiter et al, 1991;Förster and Tischendorf, 1997;Förster et al, 1999;Lange et al, 1972;Laube, 1866;Štemprok, 1986;Tischendorf, 1989). Two-mica granites are relatively rare in the Krušné hory Mts.…”

“…were studied by numerous authors (Breiter et al, 1991(Breiter et al, , 1999Förster and Tischendorf, 1997;Förster et al, 1999;Jarchovský and Štemprok, 1979;Lange et al, 1972;Štemprok, 1986;Štemprok and Šulcek, 1969;Tischendorf, 1989).…”

Monazite and zircon as major carriers of Th, U, and Y in peraluminous granites: examples from the Bohemian Massif

“…The Nejdek or Nejdek-Eibenstock pluton (hereafter, NEP) in the western part of the Krušné Hory Mountains (Erzgebirge in German) is a typical example of Variscan orebearing magmatism in this region (Breiter et al 1991Förster et al 1999). Granites of the older intrusive complex (hereafter, designated as NEP1) are predominantly coarsegrained oligoclase-biotite granites without any evidence of geochemical specialization.…”

The Krásno Sn-W ore district near Horní Slavkov: Mining history, geological and mineralogical characteristics

“…Owing to the obvious association of younger granites with the Sn-W-Li mineralization, the rocks attracted attention and were repeatedly studied during the 20 th century. The older geological, petrographical and petrochemical data were presented by Fiala (1962Fiala ( , 1968, new data were published by Jarchovský temprok (1979), temprok (1986), and Breiter et al (1991).…”