Fluid inclusion and stable isotope study of the Kasejovice gold district, central Bohemia
Authors:
Zachariáš J, Pudilová M
Published in:
Bulletin of Geosciences, volume 77, issue 3;
pages: 157 - 165;
Received 8 January 2002;
Accepted in revised form 25 March 2002;
Keywords:
gold ores,
hydrothermal processes,
geochemical controls,
fluid inclusions,
stable isotopes,
oxygen,
pressure,
temperature,
Moldanubicum,
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Abstract
Quartz gangue from the Variscan gold-bearing Kasejovice district (Jakub Mine) of the Moldanubian Drosendorf Unit, Bohemian Massif, was studied by fluid inclusion, stable isotope and SEM-CL techniques. Quartz of the early mineralization stage precipitated from a heterogeneous, unmixed, low-salinity (3.0-1.5 wt% NaCl eq.), H
2O-CO
2 fluid with minor admixture of other gases (CH
4, N
2, H
2S) at 2-1 kbar and 220-300 °C. Oxygen isotope signature of these fluids (δ
18O: +8.0 to +6‰ SMOW at 360-300 °C) is ambiguous with respect to the discrimination between deep crustal metamorphic and magmatic fluid sources, but the former one is more likely with respect to CO
2-CH
4-H
2O ratios. The late mineralization stages occurred mostly from aqueous-only fluids under decreasing temperatures (from ~200 to ~100 °C) and pressures (< 0.5 kbar). The observed variety of SEM-CL quartz textures includes oscillatory, growth and sector zoning and deformation related textures.