PRESERVATION OF δ18O VALUES OF FLUID INCLUSION WATER IN QUARTZ OVER GEOLOGICAL TIME IN AN EPITHERMAL ENVIRONMENT: BEREGOVO DEPOSIT, TRANSCARPATHIA, UKRAINE

Abstract

δ18O andδD values were measured for water in fluid inclusions in minerals from the Beregovo epithermal deposit, Transcarpathia, Ukraine. Directly measuredδ18O values for the water in inclusions in quartz were compared to calculatedδ18Oquartz values, using fluid inclusion homogenization temperatures, and published isotope equilibria constants. On the basis of this comparison it was concluded that theδ18O values of water in the fluid inclusions in quartz in epithermal environments are preserved over geological time. Further evidence for the lack of isotope exchange between fluid inclusion water and the quartz host is the similarity between the isotopic composition of water extracted from sulphides (sphalerite,δ18O= −3.5‰ andδD= −82‰; and galena,δ18O= −2.5‰ andδD= −79‰) and water extracted from coexisting quartz (δ18O= −2.8‰ andδD= −84‰).