Abstract
Sulfur isotope ratios of sulfide minerals were measured from fourteen Au-Ag mines in the Republic of Korea. Although δ34S (CDT) values show a comparatively wide range from -0.2‰ to +9.8 ‰, 90% of the values fall in a range from +1 to 7‰. For the individual deposits the values show a small variation range usually less than three per mil. The small variation range and observed 34S fractionation among sulfide minerals, indicate the precipitation of sulfides mainly from H2S under equilibrium or nearly equilibrium conditions.
Together with the data available in previous literatures, a systematic spatial variation of δ34S values for the deposits could be recognized among the deposits with different geologic environments, formation ages and workable metals. The deposits located in or near the Mugug area in the Gyeonggi massif, have ore sulfur with relatively high δ34S values, whereas the deposits in the Ryeongnam massif tend to have ore sulfur with relatively low δ34S values, although some exceptional cases have been reported. It is likely that ore sulfur in the deposits was originated mainly from the host rocks prevailed in each region, and consequently that the geochemical nature of the Gyeonggi and Ryeongnam massifs is somewhat different to each other.
