Phyllosilicates from hydrothermally altered granitoid rocks in the PezinokSb-Au deposit, Western Carpathians, Slovakia

Biotites from altered granitoid rocks on Pezinok-Kolarsky vrch Hill Sb-Au d eposit belong to the phlogophite-annite series with the ratio Fe-tot/(Fe-to t + Mg) = 0.44-0.55. Mg-biotites are the dominant type and can be classifie d as phlogopites (Phl(30.09-45.79)Ann(26.67-36.00)Eas(22.93-10.22)Sid(20.31 -8.02)). Fe-biotites (annites, Phl(34.79-41.13)Ann(39.20-46.39) Eas(12.22-5 .86)Sid(13.79-6.62)) are present in the more altered rocks. The chemical co mposition of the studied biotites is governed by Tschermak's substitution, dioctahedral-trioctahedral substitution and A(-1)(Si+1Al-1)IV-substitution. Interlayer deficient occupancy of A site is probably caused by postmagmati c hydrothermal alteration and can be explained by A(-1)(Si+1Al-1)(IV)-subst itution. The studied tri-trioctahedral chlorites come from the clinochlore- chamosite isomorphic series and they originated from biotites. According to the classification of Wiewiora & Weiss (1990) or Weiss (1991), they can be divided into two groups: ferrous clinochlores (schematic formula Mg34.39-3 6.32Fe28.31-37.07X24.02-35.39) and magnesium chamosites (schematic formula Mg34.33-37.90Fe34.76-39.32X23.18-28.30). Ferrous clinochlore is the dominan t type of chlorite. The chemical composition of chlorites is governed by do minant FeMg-1-substitution and also by Tschermak's substitution and dioctah edral substitution. The content of impurities (K, Ca, Na) is very low. Whit e K-micas were formed mainly by alteration of alkali feldspars or plagiocla ses and can be divided into: phengitic muscovites and illites. Phengitic mu scovites in the phengitic component (Brigatti et al. 2000) range from 0.17 to 0.25. The content of Ti is 0.016-01020 a.p. II oxygens and indicates pos tmagmatic to hydrothermal origin (Miller et al. 1981). The content of inter layer occupancy (K + Ca + Na) ranges from 0.905 to 0.964 a.p. 11 oxygens an d agrees with data from Konings et al. (1984), Piantone et al. (1994) and o thers. The chemical composition of phengitic muscovites is governed by Tsch ermak's substitution, dioctahedral-trioctahedral substitution and A(-1)(Si1Al-1)(IV)-substitution. The phengitic component for illites is 0.02-0.14. The content of Ti (0.005-0.019 a.p. II oxygens) indicates hydrothermal orig in (Miller ct al. 1981). The content of K ranges from 0.770 to 0.926 a.p. 1 1 oxygens and agrees with data from Cathelineau & Izquierdo (1988), Aja et al. (1991 a,b), Srodron & Eberl (1984) and others. The chemical composition of illites is governed by substitutions A(-1)(Si+1Al-1)(IV) -substitution, dioctahedral-trioctahedral substitution and Tschermak's substitution.