• 자원환경지질
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• 제25권3호
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• pp.297-316
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• 1992

The Daebong gold-silver deposits is located in 8 km southwest of Cheongyang, Chungcheongnam-Do, Republic of Korea. The gold-silver-bearing hydrothermal quartz veins was formed within the Precambrian metasediments of Gyeonggi massif. Ore minerals occur as mainly of pyrite, sphalerite (0.78~6.19 wt.% Cd), galena, pyrrhotite and minor amounts of chalcopyrite, arsenopyrite, magnetite, ilmenite, chalcocite, electrum (55.00~89.55 wt.% Au) and argentite. The gangue minerals are quartz, calcite, chlorite, K-feldspar, biotite. Wall-rock alterations such as chloritization, silicification, pyritization, carbonatization and sericitization can be observed near the quartz veins. According to the mineral paragenetic sequence based on vein structure and mineral assemblages, three stage mineralizations can be recognized. Fluid inclusion, sulfur isotope and thermodynamic data show that the ore minerals were dominantly deposited at the between 388 and $204^{\circ}C$ from fluids with salinities of 8.1~0.3 wt.% equivalent NaCl, and sulfur isotope value 4.84 to 6.40 per mil of sulfides indicates igneous sources of sulfur in the hydrothermal system and fluid inclusion salinity data suggest that thermal fluids may have magmatic origin with some degree mixing of meteoric water.

• 자원환경지질
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• 제29권3호
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• pp.395-405
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• 1996

The Donjin deposits which is located in the Chinan Basin, are emplaced along $N10{\sim}40^{\circ}E$ trending fissure sets. So it is a sort of fissure-filling ore deposits. The results of paragenetic studies suggest two stages of hydrothermal mineralization; stage I: base-metal sulfides stage, stage II: late base-metal sulfides, electrum and silver-bearing sulfosalts stage. Au: Ag ratios of the electrums show that Ag atomic% are higher than that of Au. The temperature and salinity of the Donjin deposits estimated from fluid inclusion and sulfur isotope geothermometry are as follows; stage I: $240{\sim}315^{\circ}C$, 2.4~7.1 NaCl eq. wt.%, stage II: $190{\sim}268^{\circ}C$, 4.6~8.4 NaCl eq. wt.%. The estimated oxygen and sulfur fugacity during first stage mineralization, based on phase relation of associated minerals, range from $10^{-35}{\sim}10^{-39.7}$ atm. and$10^{-11}{\sim}10^{-13.4}$ atm., respectively. All these evidences suggest that the Dongjin deposits are polymetallic meso-epithermal ore deposits.

• 자원환경지질
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• 제25권4호
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• pp.379-395
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• 1992

The gold ore deposits of Nakcheon, Gongyeong and Dongmyeong mine in the Imgye district are E-W trending fissure filling veins emplaced in Precambrian Jungbongsan granite and sedimentary rocks of Cambrian Yangdeog group. The K-Ar age for vein alteration sericite and vein laced muscovite are 73 and 93 Ma, respectively. Vein structure and mineralogy indicate the three distinct depositional stages: I) basemetal sulfides and tin minerals, II) gold-basemeatl sulfides, III) gold-silver-basemetal sulfides. Major gold and silver ore minerals are electrum, native silver, pyrargyrite and argentite. Fluid inclusion data indicate that filling temperatures were from $350^{\circ}C$ to $190^{\circ}C$ through stage I, II and III. Salinities were in the range of 0.0~9.5 NaCl eq.wt.% and do not reveal any systematic trend. Intermittent boiling of ore fluid during stage I is indicated by fluid inclusions in quartz. Fluid pressure during stage I which is estimated from fluid inclusions showing boiling evidence range from 50 to 100 bars. Gold ore deposits of the Imgye district were formed under higher temperatures and lower sulfur fugacities compared with the Eunchi silver ore deposits about 8 Km apart from the Imgye district.

• 자원환경지질
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• 제27권6호
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• pp.537-548
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• 1994

The Weolyu gold-silver deposits at Hwanggan, Chungcheongbukdo, is of a late Cretaceous $(74.24{\pm}1.63Ma)$ epithermal vein-type, and is hosted in the quartz porphyry of late Cretaceous age. Based on mineral paragenetic sequence interpreted from vein structure and mineral assemblages, three stages mineralization were distinguished. A variety of ore minerals occurs including pyrite, sphalerite, chalcopyrite, galena with small amount of electrum, native silver, argentite, pearceite, sb-pearceite, argyrotite. The gangue minerals are quartz, rutile, calcite, apatite, fluorite and rhodochrocite. Wall-rock alteration such as pyritization, chloritization, sericitization, silicification is observed near the quartz veins. Au-Ag minerals were crystallized at middle and late stage of the two mineralization sequences. Results from the analysis of fluid inclusion and thermodynamic calculation indicate that Au-Ag mineral deposits were formed primarily by cooling and dilution of hydrothermal fluids($165{\sim}313^{\circ}C$, 0.4~2.4wt.% equivalent NaCl) with some degree mixing of meteoric water.

• 자원환경지질
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• 제36권6호
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• pp.391-405
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• 2003

대봉 금-은광상은 선캠브리아기 경기육괴의 호상 또는 화강편마암내에 발달된 단열대(NE, NW)를 따라 충진한 중열수 괴상석영맥광상이다. 광석광물의 산출조직과 공생관계에 의하면, 이 광상의 광화작용은 여러번의 단열작용에 의해 형성된 괴상백색석영맥(광화I시기)과 투명석영시기(광화II시기)로 구성된다. 광화I기는 3회의 substages로 구분된다. 각 substage의 광석광물은 다음과 같다: 1) 광화I시기 조기=자철석, 자류철석, 유비철석, 황철석, 섬아연석, 황동석, 2) 광화I시기 중기=자류철석, 유비철석, 황철석, 백철석, 섬아연석, 황동석, 방연석, 에렉트럼과 3) 광화I시기 말기=황철석, 섬아연석, 황동석, 방연석, 에렉트림, 휘은석. 광화II시기의 광석광물로는 황철석, 섬아연석, 황동석, 방연석 및 에렉트럼이 관찰된다. 유체포유물의 체계적 연구에 의하면, 물리-화학적 상태가 상반되는 유체가 관찰된다: 1) 광화 I시기 조기와 중기 광석광물 정출과 관련된 $H_2O-CO_2-CH_4-NaCl{\pm}N_2$ 유체(조기=균일화온도: 203∼388^{\circ}C$, 압력: 1082∼2092 bar, 염농도: 0.6∼13.4wt.%, 중기=균일화온도: 215∼280^{\circ}C$, 염농도: 0.2∼2.8wt.%), 2) 광화I시기 말기와 광화II시기 광석광물과 관련된 $H_2O-NaCl{\pm}CO_2$ 유체(광화I시기 말기=균일화온도: 205∼2$88^{\circ}C$, 압력: 670bar, 염농도: 4.5∼6.7wt.%, 광화II시기=균일화온도: 201∼358^{\circ}C$, 염농도: 0.4∼4.2wt.%)이다. 광화I시기 조기의 $H_2O-CO_2-CH_4-NaCl{\pm}N_2$계 유체는 유체압력의 차이에 의해 CO_2$ 상분리가 일어났으며 광화작용이 진행됨에 따라 $H_2O-NaCl{\pm}CO_2$계 유체로 진화되었다. 또한 여기에 기원이 다른 $H_2O$-NaCl계 유체의 유입에 의해 혼입 및 희석작용으로 염농도의 감소가 있었다고 생각된다. 광화II시기 좀더 가열된 $H_2O-NaCl{\pm}CO_2$ 계 유체는 불혼합, 희석 및 냉각작용이 있었던 것으로 생각된다. 열수용액의 {\gamma}^{34}$S__{H2S}$ 값은 3.5∼7.9{\textperthansand}$로서 황은 주로 화성기원이지만 부분적으로 모암내의 황에서도 기원되었다고 생각된다. 광화유체의 산소({\gamma}^{18}O_{H2O}$)와 수소({\gamma}$D)안정동위원소값이 광화I시기에는 각각 11∼9.${\textperthansand}$, -92∼-86${\textperthansand}$, 광화 II시기에는 각각 0.3${\textperthansand}$(${\gamma}^{18}O_{H2O}$),-93${\textperthansand}$({\gamma}$D)이며, 리본-호상구조를 보이는 것으로 보아 대봉광상의 광화유체에 대한 기원과 진화과정을 두 가지로 생각할 수 있다. 1) 마그마유체로부터 광화작용이 진행됨에 따라 계속적인 순환수의 혼입이 있었으며 2) 조기 마그마${\pm}$변성유체에서 유체압력의 차에 의해 $CO_2$ 상분리와 더불어 계속적인 ${\gamma}$D가 높은 순환수의 혼입이 있었던 것으로 해석할 수 있다.있다.

• 자원환경지질
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• 제28권6호
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• pp.541-551
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• 1995

The Yeongdeog gold-silver deposits at Jipum, Gyeongsangbugdo, is of a middle Paleogene $(45.52{\pm}1.02Ma)$ vein type, and is hosted in shale and sandstone of Cretaceous age. Based on mineral paragenesis, vein structure and mineral assemblages, the ore mineralization can be divided into two distinct depositional stages. The early stage is associated with base-metals such as pyrite, arsenopyrite (27.99~30.99 at%), hematite, rutile, pyrrhotite, sphalerite (10.53~18.42 FeS mole%), chalcopyrite and galena with wallrock alteration such as chlorite, sericite and pyrite. The late stage is characterized by the Au-Ag mineralization such as electrum, Ag-bearing tetrahedrite, freibergite, pyrargyrite, unidentified mineral, pyrite, sphalerite (1.08~5.57 FeS mole%), chalcopyrite and galena. Fluid inclusion data indicate that fluid temperatures and salinities range from 343 to $227^{\circ}C$ and from 8.3 to 5.7 wt% eq. NaCl in early stage, respectively. Temperatures and salinities of NaCl eq. wt% range from 299 to $225^{\circ}C$ and from 12.9 to 4.3 in late stage, respectively. They suggest that complex cooling histories were occured by the mixing of the fluids. Sulfur fugacity $(-logfs_2)$ deduced by mineral assemblages and composition ranges from 8.3 to 14.7 atm. in early stage, and from 8.8 to 14.5 atm. in late stage. It suggests that the mineralization was related to decrease of temperature in early stage and fluctuations of $fS_2$ with decrease of temperature in late stage. Sulfur and oxygen isotope compositions are 4.48~5.60‰ and 9.25~10.8% in early stage, and late stage is 4.84~7.00‰ and 5.7‰, respectively. It indicated that hydrothermal fluids may be magmatic origin with some degree of mixing of another water during paragenetic time.

• 자원환경지질
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• 제28권1호
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• pp.9-17
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• 1995

The Kamkye Cu-Pb-Zn-Au-Ag deposits occur as quartz veins that filled fault-related fractures of NW system developed in the Cretaceous Gyeongsang basin. Three major stages of mineral deposition are recognized: (1) the stage I associated with wall rock alteration, such as sericite, chlorite, epidote and pyrite, (2) the early stage II of base-metal mineralization such as pyrite, hematite, and small amounts of sphalerite and chalcopyrite. and the middle to late stage II of Cu-As-Sb-Au-Ag-S mineralization, such as sphalerite, chalcopyrite, galena with tetrahedrite, tennantite, pearceite, Pb-Bi-Cu-S system, argentite and electrum. (3) the stage III of supergene mineralization, such as covellite, chalcocite and malachite. K-Ar dating of alteration sericite is a late Cretaceous ($74.0{\pm}1.6Ma$) and it may be associated with granitic activity of nearby biotite granite and quartz porphyry. Fluid inclusion data suggest a complex history of boiling, cooling and dilution of ore fluids. Stage II mineralization occurred at temperatures between 370 to $220^{\circ}C$ from fluids with salinities of 8.4 to 0.9 wt.% NaCl. Early stage II($320^{\circ}C$, 2.0 wt.% NaCl) may be boiled due to repeated fracturing which opened up the hydrothermal system to the land surface, and which resulted in a base-metal sulfide. Whilst the fractures were opened to the surface, mixing of middle-late stage II ore fluids with meteoric waters resulted in deposition of Cu-As-Sb-Au-Ag minerals from low temperature fluids(${\leq}290^{\circ}C$). Boiling of ore fluids may be occured at a pressure of 112 bar and a depth of 412 m. Equilibrium thermodynamic interpretation of sphalerite-tetraherite assemblages in middle stage II indicates that the ore-forming fluid had log fugacities of $S_2$ of -6.6~-9.4 atm.

• 자원환경지질
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• 제20권1호
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• pp.1-18
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• 1987

The Cheolam silver deposits are emplaced along the fractures in breccia dike and the Hongjesa granite. Breccia dike contains fragments of late Cretaceous acidic volcanic rocks and other fragments of various rocks distributed in the mine area. Therefore it is presumed that the mineralization was taken place in later than late Cretaceous time. Mineral paragenesis is complicated by multiple episodes of fracturing. Six distinct depositional stages can be recognized: stage I, deposition of base metal sulfides; stage II, deposition of base metal sulfides and silver minerals; stage III, deposition of carbonates; stage IV, deposition of silver minerals and base metal sulfides; stage V, deposition of silver minerals; stage VI, deposition of barren quartz. Silver minerals from the deposits are native silver, acanthite, pyrargyrite, argentian tetrahedrite, stephanite, polybasite, pearceite, allargentum, antimonial silver and electrum. Fluid inclusion studies ware carried out for stage I, II, IV and VI quartz and stage III calcite. Homogenization temperatures for each stage are as follows: stage I, from $225^{\circ}$ to $360^{\circ}C$; stage II, from $145^{\circ}$ to $220^{\circ}C$; stage III, from $175^{\circ}$ to $240^{\circ}C$; stage IV, from $130^{\circ}$ to $185^{\circ}C$; stage VI, from $120^{\circ}$ to $145^{\circ}C$. Salinities of ore fluids were in the range of 4 and 10 wt.% equivalent NaCl over stage I and stage VI. Ore mineralogical data of each stage indicate that temperatures are within the range of homogenization temperature of fluid inclusions and sulfur fugacities declined steadily from $10^{-9.7}atm$. to $10^{-18.7}atm$. through stage I into stage V.

• 자원환경지질
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• 제22권3호
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• pp.237-252
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• 1989

The Inseong gold-silver mine is located 3Km northwest of Suanbo, Choongcheongbugdo, Republic of Korea. The mine occurs in the shear zone formed by tension fractures within the Hwanggangri Formation of the Ogcheon metamorphic belt. Ore minerals found in the gold-silver bearing hydrothermal quartz vein composed mainly of pyrite, arsenopyrite, sphalerite, galena and minor amount of chalcopyrite, pyrrhotite, stannite, bismuthininte, native bismuth, chalcocite, electrum and tellurian canfieldite(?). The gangue minerals are quartz, calcite, chlorite and rhodochrocite. Wallrock alterations such as chloritization, silicitication, pyritization, carbonitization and sericitization can be observed in or around the quartz vein. According to the paragenetic sequence, quartz vein structure and mineral assemnlages, three different stages of ore formation can be recognized. The physico-chemical environment of ore formation in this deposit shows slight variation from stage to stage, but the condition of main ore deposition can be summarized as follows. Fluid inclusion, S-istope geothermometry and geothermometry based on mineral chemistry by use of arsenopyrite and chlorite show the ore was formed at temperature between 399 and $210^{\circ}C$ from fluids with salinities of 3.3-5.8 wt.% equivalent NaCl. It indicates that pressure during the mineralization is less than 0.6 Kb corresponding to a depth not greater than 1Km. S-isotope data suggests that thermal fluid may have magmatic origin wit some degree of mixing with meteoric water. In coclusion, the Inseong gold-silver deposit was formed at shallow depth and relatively high-temperature possibly with steep geothermal gradient under xenothermal condition.

• 자원환경지질
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• 제24권2호
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• pp.151-165
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• 1991

The Au-Ag deposits of the Euiseong area occurred in quartz veins which filled fissures in Cretaceous sedimentary and volcanic rocks. These ore veins can be classified in two types of deposits based on metallic mineral assemblages as follow: a pyrite type gold-silver deposit (Hoedong mine), characterized by Cu sulfides with Au-Ag alloy, and a Sb-rich silver deposit (Keumdongdo mine), characterized by base metal with Ag-bearing sulfosalts. Mineralogic and fluid inclusion evidences suggest that the ore minerals of these deposits was deposited from initial high temperatures (near $350^{\circ}C$) to later lower temperatures ($200^{\circ}C$) with moderate salinity fluids ranging from 5.8 to 3.8 eq. wt. % NaCl. The gold-silver mineralization of the Hoedong mine occurred at temperatures between 300 and $200^{\circ}C$ from fluids with log $f_{s_2}$ of -10 ~ -16 atm. The antimony - silver mineralization of the Keumdongdo mine were deposited at the higher temperatures (350 to $250^{\circ}C$) and $f_{S_2}$ (-10 ~ -13 atm) than gold mineralization of the Hoedong mine. The calculated log f02 of fluids at $250^{\circ}C$ in two deposits are -32 to -34 atm and -36.5 to -38.5 atm, respectively. Boiling evidences indicate that the ore mineralization of the Hoedong mine occurred at more shallow depth (0.5km) than that (1km) of the Keumdongdo mine. The above differences of depositional environments between two deposits caused the compositional changes of ore minerals such as electrum and sphalerite.