三光 金 鑛床의 鑛化 溫度 및 根源에 關한 硏究

Study on the temperature and the origin of mineralization at the Samkwang Au deposits

The Samkwang mine is one of gold deposits distributed mainly in the southwestern province (Chungnam) of the Korean peninsula. Golds occur in quartz veins aged of 223±4 MA according to K-Ar age dating from muscovite in a pegmatitic quartz vein. Quantz veins intrude Precambrian biotite-granite gneiss and mica schist of unknown age. Fluid inclusions in the quartz show a range of homogenization temperatures from 159 to 274℃. A calculated temperature from the isotopes of the galena-sphalerite pair is 375℃. Two phases-fluid inclusions homogenized either by liquid or vapor phase are frequently observed in specimens over 260℃, which may indicate the boiling of the fluids. Pressure of formation of the quartz veins inferred by the homogenization temperatures of liquid-CO₂ bearing fluid is 1kb. Based on these data, it is assumed that the temperature of the formation of the Samkwang mine may lie in between 350°-230℃. δ³⁴S∑s values of sulphide minerals show narrow range of +2.1 to +4.6, and show a trend of enrichments of δ³⁴S in the fluid from deep to the surface. δ³⁴S∑s in the fluid estimated is less than 3 permil, suggesting sulphur fluid originated from the magma.