Journal of the Mineralogical Society of Korea (한국광물학회지)

The Mineralogical Society of Korea (한국광물학회)
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Gold Mineralization of the Youngbogari Mine, Youngdong Area

영동지역 영보가리 광산의 금광화 작용

  • Heo, Chul-Ho (Mineral Resources Group, Geology & Geoinformation Division, Korea Institute of Geoscience and Mineral Resources(KIGAM)) ;
  • Chi, Se-Jung (Mineral Resources Group, Geology & Geoinformation Division, Korea Institute of Geoscience and Mineral Resources(KIGAM))
  • 허철호 (한국지질자원연구원 지질기반정보연구부 광물자원연구실) ;
  • 지세정 (한국지질자원연구원 지질기반정보연구부 광물자원연구실)
  • Published : 2007.06.30
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Abstract

Electrum-sulfide mineralization of the Youngbogari mine area occurred in two stages of massive quartz veins that fill the fractures along the fault/shear zones in the Precambrian gneiss. Ore mineralogy is simple, consisting of arsenopyrite $(31.4{\sim}33.4atom.%As)$, pyrite, sphalerite $(4.1{\sim}17.6mole%FeS)$, galena, chalcopyrite, argentite, and electrum. Electrum $(60.3{\sim}87.6atom.%Ag)$ is associated with galena, chalcopyrite and late sphalerite infilling the fractures in quartz and sulfides. Fluid inclusion data show that ore mineralization was formed from $H_2O-CO_2-CH_4-NaCl$ fluids $(X_{CO2+CH4}=0.0\;to\;0.2)$ with low salinities (0 to 10wt.% eq. NaCl) at temperatures between $200^{\circ}\;and\;370^{\circ}C$. Gold-silver mineralization occurred later than the base-metal sulfide deposition, at temperatures near $250^{\circ}C$ and was probably a result of cooling and decreasing sulfur fugacity caused by sulfide precipitation and/or $H_2S$ loss through fluid unmixing.

충북 영동지역 영보가리 광산의 에렉트럼(은함량=$60.3{\sim}87.6atom.%$)-황화광물 광화작용은 선캠브리아기 편마암 내의 단층열극을 충진한 석영맥으로 산출된다. 석영맥은 광물조성이 단순한 괴상이며, 구조적으로 2회에 걸쳐 형성되었다. 산출 광석광물은 비교적 단순하며, 유비철석(비소함량= $31.4{\sim}33.4atom.%$), 황철석, 섬아연석(철함량 = $4.1{\sim}17.6mole%$ FeS), 방연석, 황동석, 휘은석 및 에렉트럼 등으로 구성된다. 유체포유물연구에 의하면, 광화작용은 $CO_2+CH_4$ 함량$(X_{CO2+EH4}=0.0{\sim}0.2)$과 저염도 ($0{\sim}10wt.%$ NaCl 상당염농도)를 갖는 $H_2O-CO_2-CH_4-NaCl$계 유체로부터 $200^{\circ}{\sim}370^{\circ}C$의 온도범위에서 진행되었다. 금-은침전은 천금속계 황화광물 보다는 후기, 약 $250^{\circ}C$ 근처에서 진행되었고, 유체불혼화에 따라 황화광물 침전 및 $H_2S$ 일탈이 야기되면서 주로 냉각 및 유황분압의 감소에 기인하였다.

Keywords

References

  1. Barton, P.B., Jr. and Toulmin, P. III. (1964) The electrum-tarnish method for the determination of the fugacity of sulfur in laboratory sulfide system. Geochimica et Cosmochimica Acta, 28, 619-640 https://doi.org/10.1016/0016-7037(64)90082-1
  2. Barton, P.B., Jr. and Skinner, B. J. (1979) Sulfide mineral stabilities: In. Barnes, H.L., ed. Geochemistry of hydrothermal ore deposits, New York, Wiley, 278-403
  3. Bowers, T. S. and Helgeson, H. C. (1983) Calculation of thermodynamic and geochemical consequences of non ideal mixing in the system $H_2O-CO_2-NaCl$ on phase relations in geologic systems: Equation of state for $H_2O-CO_2-NaCl$ fluids at high pressures and temperatures. Geochimica et Cosmochimica Acta, 47, 1247-1275 https://doi.org/10.1016/0016-7037(83)90066-2
  4. Burruss, R.C. (1981) Analysis of fluid inclusions : Phase equilibria at constant volume. American Journal of Science, 281, 1104-1126 https://doi.org/10.2475/ajs.281.8.1104
  5. Choo, S. H. and Kim, S. J. (1985) A study of Rb-Sr age determinations on the Ryeongnam Massif (I): Pyeonghae, Buncheon and Kimcheon granitic gneisses. Annual Report 85-24, Korea Institute Energy and Resources, 7-39
  6. Collins, P.L.F. (1979) Gas hydrates in $CO_2$-bearing fluid inclusion and the use of freezing data for estimation of salinity. Economic Geology, 74, 1435-1444 https://doi.org/10.2113/gsecongeo.74.6.1435
  7. Crawford, M.L. (1981) Phase equilibria in aqueous fluid inclusions. Mineralogical Association Canada Short Course Handbook, 6, 75-100
  8. Heo, C. H., Yun, S.T. and So, C. S. (2003) Sulfur isotope characteristics of mesothermal-type gold deposits in the Boseng-Jangheung area, Korea. Neues Jahrbuch fur Mineralogie Abhandlungen, 178, 107-129 https://doi.org/10.1127/0077-7757/2003/0178-0107
  9. Hollister, L.S., Crawford, M.L., Roedder, E., Burruss, R.C., Spooner, E.T.C. and Touret, J. (1981) Practical aspects of microthermometry. Mineralogical Association of Canada Short Course Handbook, 6, 278-301
  10. Kretschmar, U. and Scott, S.D. (1976) Phase relations involving arsenopyrite in the system Fe-As-S and their application. Canadian Mineralogist, 14, 364-386
  11. Potter, R.W. III., Clynne, M.A. and Brown, D.L. (1978) Freezing point depression of aqueous sodium chloride solutions. Economic Geology, 73, 284-285 https://doi.org/10.2113/gsecongeo.73.2.284
  12. Roedder, E. (1984) Fluid inclusions. Reviews in Mineralogy, 12, 644p
  13. Scott, S.D. and Barnes, H.L. (1971) Sphalerite geothermometry and geobarometry. Economic Geology, 66, 653-669 https://doi.org/10.2113/gsecongeo.66.4.653
  14. Shelton, K.L., So, C.S. and Chang, J.S. (1988) Gold-rich meso thermal vein deposits of the Republic of Korea: Geochemical studies of the Jungwon gold area. Economic Geology, 83, 1221-1237 https://doi.org/10.2113/gsecongeo.83.6.1221
  15. Shikazono, N. (1985) A comparison of temperatures estimated from electrum-sphalerite-pyrite-argentite assemblage and filling temperature of fluid inclusions from epithermal Au-Ag vein deposits in Japan. Economic Geology, 80, 1415-1424 https://doi.org/10.2113/gsecongeo.80.5.1415
  16. Shimazaki, H., Lee, M.S., Tsusue, A. and Kaneda, H. (1986) Three epochs of gold mineralization in South Korea. Mining Geology, 36, 265-272
  17. So, C.S., Yun, S.T., Youm, S.J. and Heo, C.H. (1994) Fluid inclusion and stable isotope studies of gold- and silver-bearing vein deposits, South Korea: Silver-rich epithermal mineralization of the Keumryeong mine. Neues Jahrbuch fur Mineralogie Abhandlungen, 167, 57-88
  18. So, C.S., Yun, S.T. and Shelton, K.L. (1995) Mesothermal gold vein mineralization of the Samdong mine, Youngdong mining district, Republic of Korea. Mineralium Deposita, 30, 384-396
  19. So, C.S. and Yun, S.T. (1997) Jurassic mesothermal gold mineralization of the Samhwanghak mine, Youngdong area, Republic of Korea: Constraints on hydrothermal fluid chemistry. Economic Geology, 92, 60-80 https://doi.org/10.2113/gsecongeo.92.1.60
  20. Sterner, S.M. and Bodnar, R.J. (1984) Synthetic fluid inclusions in natural quartz I. Compositional types synthesized and applications to experimental geochemistry. Geochimica et Cosmochimica Acta, 48, 2659-2668 https://doi.org/10.1016/0016-7037(84)90314-4