ABSTRACT

Oxygen and sulfur isotopic compositions of sulfate, quartz and sulfide minerals from the veins of the Sambo lead-zinc-barite ore deposits have been measured to study their depositional conditions and evolution of ore fluids. The results are as follows: (1) The δ³⁴S values of sulfides vary from -3.9 to -13.5‰ and those of sulfates from +15.7 to +17.2‰. Isotopic temperatures from barite-sphalerite and barite-galena pairs were 210-290°C, in fairly good agreement with the homogenization temperatures of fluid inclusions in the stage II quartz. At relatively low temperatures (210-290°C), isotopic equilibria were attained between sulfate and sulfide minerals in the Sambo ore deposits. (2) Barites have homogeneous δ³⁴S and δ¹⁸O values of +15.7 to +17.2‰ and +2.4 to +3.9‰, respectively. Calculated δ¹⁸O values of ore fluids in equilibrium with barite and quartz vary from -2.1 to +0.9‰ and -4.2 to -1.3‰, respectively, suggesting a contribution of ¹⁸O depleted meteoric water to ore fluids of the Sambo deposits.