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Article

Geologica Carpathica, 1991, vol. 42, no. 5
MINERAL ASSEMBLAGES AND PHYSICAL-CHEMICAL MODELOF THE FORMATION OF GOLD-SILVER-POLYMETALLICMINERALIZATION ON THE DEPOSIT BANSKA STIAVNICA (CENTRAL SLOVAKIA)
Abstract
The authors distinguished 5 stages of the mineralization process which took place in the depth range of 0.5–1.5 km and has been characterized by cyclicity of periods of deposition of ore and vein minerals. Thermo- and cryometric study of fluid inclusions in 102 samples of quartz, sphalerite, barite and fluorite has shown that the formation of minerals occurred at a decrease of temperatures from 380 to 100 °C and lower, at pressures of 125 to 15 bar and salinity varying from 0.5 to 11.5 wt% equiv. NaCl, at periodical thermobarometric inversions, with phenomena like boiling and fluid-mixing. On the basis of thermodynamic calculations it has been determined that ore-stage minerals deposited at aS2 = 10-11–10-12, a = 10-34–10-36 (Stage lV) and aS2 = 10-16–10-17.5, aO2 = 10-44–10-46 (Stage V). It has been demonstrated that the principal factors of the deposition of early-stage ore associations were temperature decrease and pH increase, and in the late stages additionally the decrease of aO2.
Pages:
291 - 302
Published online:
0. 0. 1991