Geochemical Environment of Daerae Gold Mine, Sangju Area, Kyoungsangbukdo Province, Korea

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2005 Vol.42, Issue 6 Next Page

Geochemical Environment of Daerae Gold Mine, Sangju Area, Kyoungsangbukdo Province, Korea 경상북도 상주지역 대래 금광산의 지구화학적 환경: 허철호, 이재호
Chul-Ho Heo and Jae-Ho Lee

31 December 2005. pp. 541-551

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Abstract

Mesothermal gold mineralization of the Daerae mine was deposited in a single stages of massive quartz veins which filled the mainly NE-trending fault shear zones in the banded biotite gneiss within the Sobaegsan Massif. Hydrothermal alteration sericite yields a Ar-Ar date of 188.3±0.1 Ma. This radiometric age indicates that gold mineralization of Daerae deposit is linked temporally to the Early Jurassic, granitic magmatism related to the Daebo orogeny. The ore mineralization of veins is simple and consists mainly of rare sulfides with gold. Gold occurs as fine-grained electrum ranging from 64.8 to 72.1 atom. % Au. The sulfides occur as dominantly arsenopyrite, pyrite, sphalerite, pyrrhotite, chalcopyrite and marcasite. Thermochemical study indicates that temperature and logfS2 of the early and late ore fluids for stage I mineralization are 370° to 455℃ and -5.2 to -7.8 atm, and 355° to 400℃ and -5.0 to -7.1 atm, respectively. According to the fluid inclusion data, there are three main types of fluid inclusions as follows: type I (predominatly carbonaceous), type II (three-phase, liquid CO2-bearing), and type III (dominantly aqueous). In type I inclusions, final melting temperatures of the carbonaceous phase(Tmcarb.) occurred at temperatures of -58.2° to -58.0℃, indicating the presence of CH4 in addition to CO2. Tmcarb. of type II inclusions are -63.4° to -57.2℃, indicating variations of CH4 concentration and carbonaceous phase (CO2 + CH4) density compared with type I inclusions. Type II inclusions decrepitate before total homogenization, due to high internal pressures related ot their high CO2 contents. It is noteworthy that type II inclusions have Thtotal values of 230° to 300℃. This relatively narrow temperature range (265°± 30℃) most likely represents the depositional conditions of gold mineralization at Daerae deposit. Coexistence of type I and II inclusions in vein quartz are thought to represent immiscible fluids generated by fluid unmixing. This fluid evolutiion implies a bulk chemical evolution toward end members in H2O-CO2(-CH4) with time and is thought to indicate progressive fluid unmixing. The relationship between Thtotal and Tmice and/or Tmclathrate values of fluid inclusion indicates fluid unmixing over the temperature range of 250° to 330℃. Therefore, deposition of sulfide minerals by fluid unmixing was induced to decrease fs2 of ore fluids.

Keywords

Mesothermal-type gold

Geochemistry

Mineralogy

Fluid inclusion

경상북도 상주지역 대래광산의 중열수 금 광화작용은 소백산육괴내 흑운모 호상편마암의 북서방향 단층 전단대를 충진하고 있는 괴상의 단성 석영맥내에 배태하고 있다. 열수변질대 견운모에 대한 Ar-Ar 연령은 188.3±0.1로서 광화작용이 초기 쥬라기에 일어났음을 지시한다. 본광산의 석영맥내 광물조성은 단순하며, 주로 미약한 황화물과 금으로 구성되어 있다. 금은 세립자의 에렉트럼(64.8~72.1 atom.% Au)으로 산출한다. 황화광물로는 유비철석, 황철석, 섬아연석, 자류철석, 황동석 및 백철석이 산출된다. 열화학적 연구에 의하면, 광화 1기의 초기 및 후기 광화작용에 대한 지구화학적 침전조건을 나타내는 온도 및 황분압은 각각 370°~455℃와 -5.2~-7.8 atm과 355°~ 400℃와 -5.0~-7.1 atm 이다. 유체포유물 연구에 의하면, 3개 유형의 포유물이 산출한다. 제 1형 포유물은 탄소종이 우세하며, 제 2형 포유물은 3상이며 액상 CO2를 함유하고 있고, 제 3형 포유물은 수용성이 우세하다. 제 1형 포유물의 고상 CO2 의 용융온도 범위는 -58.2°~-58.0℃이며, CO2 외에 CH4의 존재를 지시한다. 제 2형 포유물의 고상 CO2 의 용융온도 범위는 -63.4°~-57.2℃이며, 제 1형 포유물에 비해 메탄 함량과 탄소상(이산화탄소+메탄) 밀도의 변이가 다양함을 알 수 있다. 제 2형 포유물은 균질화가 이루어지기 전에 파열하며, 이는 높은 CO2 함량과 관련되어 내부압이 높아진 것으로 사료된다. 제 2형 포유물의 균질화온도는 230°~300℃로, 비교적 좁은 온도범위(265°± 30℃)를 나타내며 대래광상의 중열수 금 광화작용은 이 온도 범위에서 일어났음을 지시해 준다. 광화작용 진행중에 균질화 온도와 염농도의 관계는 유체의 불혼화작용이 250°~330℃에서 발생했음을 지시한다. 따라서, 금 침전은 주로 유체불혼화 작용에 의하여 황화광물의 침전이 진행되면서 광화유체내 황 분압의 감소를 유도한 것으로 사료된다.

키워드

중열수 금

지구화학

광물학

유체포유물

References

Barton, P. B. Jr. and Toulmin, P. III., 1964, “The electrum tarnish method for the determination of the fugacity of sulfur I laboratory sulfide system”, Geochimica et Cosmochimica Acta , Vol. 28, pp. 619-640.
Barton, P. B. Jr. and Toulmin, P. III., 1966, “Phasr relations involving sphalerite in the Fe-Zn-S system”, Economic Geology, Vol. 61, pp. 815-849.
Bowers, T. S. and Helgeson, H. C., 1983, “Calculation of the thermodynamic and geochemical consequenes of nonideal mixing in the system H2O-CO2-NaCl on phase relations in geologic systems: Metamorphic equilibria at high pressures and temperatures”, American Mineralogists, Vol. 68, pp. 1059-1075.
Burruss, R. C. 1981, “Analysis of fluid inclusions: Phase euilibria at constant volume”, American Journal of Science, Vol. 281, pp. 1104-1126.
Choi, S.G., Wee, S.M., 1992, “The genetic characteristics of gold and/or silver deposits related to chemical composition of electrum in central Korea”. Journal of Geological Society of Korea Vol. 28, pp. 196-217.
Collins, P.L.F., 1979, “Gas hydrates in CO2-bearing fluid inclusions and the use of freezing data for estimation of salinity”. Economic Geology, Vol. 74, pp. 1435-1444.
Haynes, F.M., 1985, “Determination of fluid inclusion compositions by sequential freezing”. Economic Geology., Vol., 80, pp. 1436-1439.
Hedenquist, J.W., Henley, R.W., 1985, “The importance of CO2 on freezing point measurements of fluid inclusions: Evidence from active geothermal systems and implications for epithermal ore deposition”. Economic Geoogyl., Vol. 80, pp. 1379-1406.
Heo, C. H., Yun, S. T. and So, C. S., 2003, “Sulfur isotope characteristics of mesothermal-type gold deposits in the Boseong-Jangheung area, Korea”, Neues Jahrbuch fü Mineralogie Abhandlungen, Vol. 178, pp. 107-129.
Hollister, L.S., 1981, “Information intrinsically available from fluid inclusions”. Mineralogical Association of Canadian, Short Course Handbook, Vol. 6, pp. 1-12.
Kretschmar, U. and Scott, S. D., 1976, “Phase relations involving arsenopyrite I the Fe-As-S and their application”, Canadian Mineralogists, Vol. 14, pp. 364-386.
Lee, S. W., 1986, “Metamorphism of the gneiss complex in the southwestern region of the Sobaegsan Massif”, In Memoirs in celebration of the sixtiethirthday of Professor Sang Man Lee, Seoul National Univesity, Seoul, pp. 1131-1140.
Potter, R.W., Clynne, M.A., Brown, K.L., 1978, “Freezing point depression of aqueous sodium chloride solutions”. Economic Geology., Vol. 73, pp. 284-285.
Roedder, E., 1984, “Interpretation and utilization of inclusion measurements: temperature, pressure and density at trapping”. In: Roedder E (eds.) Fluid inclusions. Reviews in Mineralogy Vol. 12 pp. 252-289.
Scott, S. D. and Barnes, H. L., 1971, “Spalerite geothermometry and geobarometry”, Economic Geology, Vol. 66, pp. 653-669.
Shelton, K. L., So, C. S. and Chang, J. S., 1988, “Gold-rich mesothermal vein deposits of the Republic of Korea: Geochemical studies of the Jungwon gold area”, Eonomic Geology, Vol. 83, pp. 1221-1237.
Shelton, K.L., So, C.S., Haeussler, G.T., Lee, K.Y., Chi, S.J., 1990, “Geochemical studies of the Tongyoung gold-silver deposits, Republic of Korea: Evidence of meteoric water dominance in a Te-bearing epithermal system”. Economic Geoogyl., Vol. 85, pp. 1114-1132.
So, C.S., Yun, S.T., Shelton, K.L., 1995, “Mesothermal gold vein mineralization of the Samdong mine, Youngdong mining district, Republic of Korea”. Mineralium Deposita , Vol. 30, pp. 384-396.
So, C.S., Yun, S.T., 1997, “Jurassic mesothermal gold mineralization of the Samhwanghak mine, Republic of Korea: Geochemistry of magmatic hydrothermal gold deposits”. Economic geology, Vol. 92, pp. 60-80.

Information

Publisher :The Korean Society of Mineral and Energy Resources Engineers
Publisher(Ko) :한국자원공학회
Journal Title :Journal of the Korean Society for Geosystem Engineering
Journal Title(Ko) :한국지구시스템공학회지
Volume : 42
No :6
Pages :541-551

[1] Barton, P. B. Jr. and Toulmin, P. III., 1964, “The electrum tarnish method for the determination of the fugacity of sulfur I laboratory sulfide system”, Geochimica et Cosmochimica Acta , Vol. 28, pp. 619-640.

[2] Barton, P. B. Jr. and Toulmin, P. III., 1966, “Phasr relations involving sphalerite in the Fe-Zn-S system”, Economic Geology, Vol. 61, pp. 815-849.

[3] Bowers, T. S. and Helgeson, H. C., 1983, “Calculation of the thermodynamic and geochemical consequenes of nonideal mixing in the system H2O-CO2-NaCl on phase relations in geologic systems: Metamorphic equilibria at high pressures and temperatures”, American Mineralogists, Vol. 68, pp. 1059-1075.

[4] Burruss, R. C. 1981, “Analysis of fluid inclusions: Phase euilibria at constant volume”, American Journal of Science, Vol. 281, pp. 1104-1126.

[5] Choi, S.G., Wee, S.M., 1992, “The genetic characteristics of gold and/or silver deposits related to chemical composition of electrum in central Korea”. Journal of Geological Society of Korea Vol. 28, pp. 196-217.

[6] Collins, P.L.F., 1979, “Gas hydrates in CO2-bearing fluid inclusions and the use of freezing data for estimation of salinity”. Economic Geology, Vol. 74, pp. 1435-1444.

[7] Haynes, F.M., 1985, “Determination of fluid inclusion compositions by sequential freezing”. Economic Geology., Vol., 80, pp. 1436-1439.

[8] Hedenquist, J.W., Henley, R.W., 1985, “The importance of CO2 on freezing point measurements of fluid inclusions: Evidence from active geothermal systems and implications for epithermal ore deposition”. Economic Geoogyl., Vol. 80, pp. 1379-1406.

[9] Heo, C. H., Yun, S. T. and So, C. S., 2003, “Sulfur isotope characteristics of mesothermal-type gold deposits in the Boseong-Jangheung area, Korea”, Neues Jahrbuch fü Mineralogie Abhandlungen, Vol. 178, pp. 107-129.

[10] Hollister, L.S., 1981, “Information intrinsically available from fluid inclusions”. Mineralogical Association of Canadian, Short Course Handbook, Vol. 6, pp. 1-12.

[11] Kretschmar, U. and Scott, S. D., 1976, “Phase relations involving arsenopyrite I the Fe-As-S and their application”, Canadian Mineralogists, Vol. 14, pp. 364-386.

[12] Lee, S. W., 1986, “Metamorphism of the gneiss complex in the southwestern region of the Sobaegsan Massif”, In Memoirs in celebration of the sixtiethirthday of Professor Sang Man Lee, Seoul National Univesity, Seoul, pp. 1131-1140.

[13] Potter, R.W., Clynne, M.A., Brown, K.L., 1978, “Freezing point depression of aqueous sodium chloride solutions”. Economic Geology., Vol. 73, pp. 284-285.

[14] Roedder, E., 1984, “Interpretation and utilization of inclusion measurements: temperature, pressure and density at trapping”. In: Roedder E (eds.) Fluid inclusions. Reviews in Mineralogy Vol. 12 pp. 252-289.

[15] Scott, S. D. and Barnes, H. L., 1971, “Spalerite geothermometry and geobarometry”, Economic Geology, Vol. 66, pp. 653-669.

[16] Shelton, K. L., So, C. S. and Chang, J. S., 1988, “Gold-rich mesothermal vein deposits of the Republic of Korea: Geochemical studies of the Jungwon gold area”, Eonomic Geology, Vol. 83, pp. 1221-1237.

[17] Shelton, K.L., So, C.S., Haeussler, G.T., Lee, K.Y., Chi, S.J., 1990, “Geochemical studies of the Tongyoung gold-silver deposits, Republic of Korea: Evidence of meteoric water dominance in a Te-bearing epithermal system”. Economic Geoogyl., Vol. 85, pp. 1114-1132.

[18] So, C.S., Yun, S.T., Shelton, K.L., 1995, “Mesothermal gold vein mineralization of the Samdong mine, Youngdong mining district, Republic of Korea”. Mineralium Deposita , Vol. 30, pp. 384-396.

[19] So, C.S., Yun, S.T., 1997, “Jurassic mesothermal gold mineralization of the Samhwanghak mine, Republic of Korea: Geochemistry of magmatic hydrothermal gold deposits”. Economic geology, Vol. 92, pp. 60-80.

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