Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

The gold-silver mineral deposit of the Oknam mine in the Taebaegsan metallogenic belt occurs as gold-silver-bearing rhodochrosite veins in biotite schist and phyllite of the Precambrian Yulri Group. Five stages of ore deposition are recognized, each showing a definite mineral assemblage. General mineral parageneses in veins associated with gold and silver vary inwardly from the vein margin: arsenopyrite+pyrite ⇒sphalerite+chalcopyrite+galena+gold⇒galena+Ag-bearing minerals. The d34S values of ore sulfides have a relatively narrow range between 2.8 and 7.0 per mil. The calculated d34SSs values of ore fluids are 2.7 to 5.5 per mil, indicating a deep-seated igneous source of sulfur. The d13C values of rhodochrosite in ores range between -6.98 and -3.47 per mil. It is likely that the carbon isotope value in the ore fluids may be compatible with a deep-seated magmatic carbon. Oxygen and hydogen isotope studies revealed that d18O and dD values of waters in the ore fluids decreased gradually with time from +8.9 and -72 per mil (stage III) to 0.0 and -77 per mil (stage IV), respectively. This indicates that magmatic water was dominant during the stage III mineralization but was progressively replaced by meteoric water during the stage IV mineralization.