Acta Geodynamica et Geomaterialia

Title: ARGILLIZATION OF TOPAZ-BEARING GRANITES IN THE HUB STOCK, HORNI SLAVKOV-KRASNO SN-W ORE DISTRICT (BOHEMIAN MASSIF, CZECH REPUBLIC)
Authors: Šťastný Martin and René Miloš
DOI: 10.13168/AGG.2014.0008
Journal: Acta Geodynamica et Geomaterialia, Vol. 11, No. 3 (175), Prague 2014
Full Text: PDF file (3.8 MB)
Keywords: Bohemian Massif, Saxothuringian Zone, topaz granite, argillization, clay minerals, dickite, tosudite
Abstract: Argillized granites from the Hub stock contain a clay mineral assemblage formed by dickite, illite, tosudite and smectite. These granites occur in the upper part of the topaz granite stock, immediately beneath topaz–mica greisens consisting of quartz, clay minerals, lithium mica (protolithionite) and topaz. Argillized granites are enriched in Si (up to 78 wt.% SiO2), Fe (0.5–3 wt.% FeOtot.), F (up to 1.6 wt.%), Rb (830–1380 ppm), Li (515–2317 ppm), Nb (25–435 ppm) and Ta (21–64 ppm), but poor in Th (2–9 ppm), Zr (7–35 ppm) and bulk of REE (3–7 ppm). Newly recognized tosudite was identified on the basis of d (001) 29.4 Å XRD reflection on natural, oriented sample and 31.6 Å reflection after ethylene glycol treatment. The d (060) reflection appeared at 1.493 Å. The tosudite originated, according to fluid inclusion study of quartz from quartz veins at temperatures of 374–393 ºC. The hydrothermal activity of Li-enriched solutions, originated by muscovitization of Li-micas from greisenized topaz–albite granites and greisens was satisfactory for the formation of tosudite. The clay mineral assemblage (dickite, illite and smectite) originated, according to fluid inclusion study of fluorite, at temperatures ranging between 90 ºC and 185 ºC.