• 자원환경지질
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• 제26권2호
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• pp.145-154
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• 1993

Gold-silver deposits in the Kwangyang-Seungju area are emplaced along $N4^{\circ}{\sim}10^{\circ}W$ to $N40^{\circ}{\sim}60^{\circ}W$ trending fissures and fault in Pre-cambrian Jirisan gneiss complex or Cretaceous diorite. Mineral constituents of the ore from above deposits are composed mainly of pyrite, arsenopyrite, pyrrhotite, magnetite, sphalerite, chalcopyrite, galena and minor amount of electrum, tetrahedrite, miargyrite, stannite, covellite and goethite. The gangue minerals are predominantly quartz and calcite. Gold minerals consist mostly of electrum with a 56.19~79.24 wt% Au and closely associated with pyrite, chalcopyrite, miargyrite and galena. K-Ar analysis of the altered sericite from the Beonjeong mine yielded a date of $94.2{\pm}2.4\;Ma$ (Lee, 1992). This indicates a likely genetic tie between ore mineralization and intrusion of the middle Cretaceous diorite ($108{\pm}4\;Ma$). The ${\delta}^{34}S$ values ranged from +1.0 to 8.3‰ with an average of +4.4‰ suggest that the sulfur in the sulfides may be magmatic origin. The temperatures of mineralization by the sulfur isotopic composition with coexisting pyrite-galena and pyrite-chalcopyrite from Beonjeong and Jeungheung mines were $343^{\circ}C$ and $375^{\circ}C$ respectively. This temperature is in reasonable agreement with the homogenization temperature of primary fluid inclusion quartz ($330^{\circ}C$ to $390^{\circ}C$; Park.1989). Four samples of quartz from ore veins have ${\delta}^{18}O$ values of +6.9~+10.6‰ (mean=8.9‰) and three whole rock samples have ${\delta}^{18}O$ values of +7.4~+10.2‰ with an average of 7.4‰. These values are similar with those of the Cretaceous Bulgugsa granite in South Korea (mean=8.3‰; Kim et al. 1991). The calculated ${\delta}^{18}O_{water}$ in the ore-forming fluid using fractionation factors of Bulgugsa et al. (1973) range from -1.3 to -2.3‰. These values suggest that the fluid was dominated by progressive meteoric water inundation through mineralization.

• 자원환경지질
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• 제54권6호
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• pp.753-765
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• 2021

동원광상은 옥천대 북서부 태백산분지 내에 분포하는 조선누층군의 변성암류, 퇴적암류 또는 화성암류 내에 발달된 열극을 충진하여 생성된 함 금-은 열수맥상 광상으로, 괴상 및 각력상 조직과 함께 정동의 발달 등 복합적인 조직적 특성을 보여준다. 동원광상의 맥상 광화작용은 지구조적 운동(tectonic break)에 의하여 광화 1시기(stage I)와 광화 2시기(stage II)로 구분된다. 광화 1시기는 석영맥의 생성과 함께 주된 함 금·은 광물인 에렉트럼(electrum)과 함께 황화광물, 산화광물 및 황염광물 등이 산출한 시기로서, 공생관계와 광물 조합 특성 등에 의하여 세 단계의 광화시기(초기, 중기, 후기)로 구분된다. 광화 1시기의 초기에는 주로 황철석, 자철석, 자류철석, 유비철석 등이 산출되었다. 중기에는 주된 금-은 광화작용이 진행되어 에렉트럼과 함께 섬아연석, 황동석, 방연석 등의 황화광물과 함 은 광물 및 황염광물 등이 산출되었다. 후기에는 황철석, 섬아연석, 방연석 등과 함께 함 은·안티몬 광물 등이 산출되었다. 광화 2시기는 주 광화작용 이후의 금속 광화작용이 이루어지지 않은 방해석과 백운석맥의 생성시기이다. 동원광상 광화작용은 초기 고온(≥430℃)의 열수유체 유입으로 시작되어 냉각과 비등작용 및 상대적으로 천부를 순환한 열수유체 또는 천수의 혼입 등에 의하여 ≥430℃~≤230℃의 온도조건에서 6.0 to 0.4 wt. percent NaCl 상당 염농도를 갖는 유체에서 진행되었다. 동원광상의 광물 공생관계 변화는 이러한 열수계의 진화에 의한 온도와 황 분압 조건의 감소 등의 환경변화가 반영된 결과이다. 동원광상은 한국형 금·은 광상 및 금-은 혼합형 광상에 해당하는 중/천열수 광상에 대비된다.

• 자원환경지질
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• 제32권3호
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• pp.237-245
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• 1999

The Mujeong au-Ag hydrothermal vein type deposits occur within the Teriary igneous rocks of the Janggi basin. Ore minerals consist of pyrite, pyrrhotite, sphalertite, chalcopyrite, galena, cosalite, lillianite, argentite and electrum, and associated with epidotization, sericitization and pyritization. Fluid inclusion studies reveal that ore fluids were low saline with a simple NaCl-$H_{2}O$ system. Fluid inclusion data indicate that homogenization temperatures and salinities of fluid are 150 to $340^{\circ}C$ and 1.0 to 6.5wt.% NaCl equivalent, respectively. Sulfur isotope compositions of sulfied minerals ( ${\delta}^{34}S$=6.2 to 9.6$\textperthousand$) indicate that the ${\delta}^{34}S_{H2S}$ value of ore fluids was about 10.4$\textperthousand$. This ${\delta}^{34}S_{H2S}$ value is likely consistent with and hydrothermal sulfur, whereas the fluids were highly influenced by mixing with meteoric water. Measured and calculated oxygen and hydrogen isotope values (${\delta}^{18}O_{H2O}$=-2.7 to 3.4 $\textperthousand$, ${\delta}D_{H2O}$ = -83.6 to -52.7 $\textperthousand$) of ore forming fluids suggest mixing with hydrothermal and meteoric water. Equilibrium thermodynamic interpretation by mineral assemblages and chemistry indicates that sulfur fugacities (-log $fs_2$) ore forming fluids range from 9.0 to 12.6 atm stage II.

• 자원환경지질
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• 제17권4호
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• pp.245-258
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• 1984

Geoje copper ore deposits are fissure filled copper veins which developed in late Cretaceous pyroclastics, andesite and shale. Mineral paragenesis reveals a division of the hydrothermal mineralization into three stages: Stage I, deposition of pyrite, magnetite, specularite, quartz and chlorite; Stage II, deposition of chalcopyrite, sphalerite, galena, tetrahedrite, aikinite, cosalite, electrum, quartz and chlorite; Stage III, deposition of barren calcite. Filling temperatures of fluid inclusions in quartz of stage I range from 171 to $282^{\circ}C$ whereas fluid inclusions in quartz and sphalerite of stage II range from 213 to $262^{\circ}C$ and from 186 to $301^{\circ}C$ respectively. Salinities of fluid inclusions in quartz of stage I range from 5.2 to 11.2 weight percent equivalent to NaCl. Salinities of fluid inclusions in quartz and sphalerite of stage II range from 6.6 to 10.9 and from 7.1 to 14.4 weight percent equivalent NaCl. Salinities of ore fluid during major mineralization stage in this deposits reveal nearly the same ranges as those of many copper deposits in Koseong copper mining district which located about 30km apart from Geoje mine. But filling temperatures of fluid inclusions formed during major copper mineralization stage in this deposits show slightly lower than those of copper deposits in Koseong copper mining district.

• 자원환경지질
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• 제23권1호
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• pp.1-9
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• 1990

A couple of Au-Ag-bearing epithermal quartz veins of Cretaceous(87.9Ma) in age are developed in the Cretaceous(112Ma) granodiorite batholith which was emplaced in Mesozoic Baegyari sedimentary formation. Au minerals consist mostly of electrum with a 54.2-61.9 wt% Au and are closely associated with sulfide minerals including pyrite, chalcopyrite, pyrrhotite, galena and sphalerite. Homogenization temperatures of fluid inclusions in quartz, fluorite and calcite are $196-368^{\circ}C$ (avg. $240^{\circ}C$), $74-176^{\circ}C$ (avg. $115^{\circ}C$) and $75-200^{\circ}C$ (avg. $119^{\circ}C$) respectively. Sulfur isotopic compositions( +5- +8‰) of ore sulfides indicate a deep-seated sulfur origin. Oxygen isotope compositions of different stages of quartz vary from +5.6 to +9.3‰ and calculated ${\delta}^{18}O$ values of ore fluid at $250^{\circ}C$ range from -3.2 to +0.4‰, reflecting an isotopically evolved ore fluid mixed with a $^{18}O$ depleted meteoric water under the variable mixing ratios between hydrothermal and meteoric waters. Isotopic data of calcite minerals support the above conclusions.

• 자원환경지질
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• 제29권2호
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• pp.119-127
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• 1996

Electrum-sulfide minerals of the Namsan Au-Ag mine were deposited in two stages of quartz and calcite veins that fill fault planes in Mesozoic granitic rocks (230~155 Ma). The K/Ar radiometric dating of hydrothermal sericite indicates that mineralization is early Cretaceous age ($127{\pm}3.0Ma$). Mineralogic, fluid inclusion and sulfur isotopic data show that ore minerals were deposited at temperatures between $340^{\circ}C$ and $200^{\circ}C$ from fluid with salinities of 3 to 6 equiv. wt % NaCl. Evidence of fluid boiling (and $CO_2$ effervescence) indicates a maximum pressures of 100 bars. The formation temperature and $fs_2$, of Au-mineralization from the Namsan mines are mainly $280{\sim}230^{\circ}C$ and $10^{-11}{\sim}10^{-13}$ atm, respectively. Au deposition was likely a result of boiling caused to chemical change (pH, $f_{O2}$, ${\Sigma}_{H_2S{\cdot}{\cdot}}$) of ore-fluids. Sulfur isotope composition of sulfide minerals (${\delta}^{34}S=5.1$ to 8.2‰) are consistent with ${\delta}^{34}S_{{\Sigma}{H2S}}$ value of +6 to +7‰, suggesting an igneous source of sulfur partially mixed with wall-rock sulfur.

• 자원환경지질
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• 제21권1호
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• pp.17-27
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• 1988

The Cretaceous Jinsan gold-bearing hydrothermal veins occur within the Late Proterozoic to Mid Ordovician metasedimentary rocks, intruded by Early Cretaceous pink-feldspar granite($142{\pm}2.0m.y.$). Electrum-galena-sphalerite mineralization was deposited in three stages of quartz and calcite veins. Quartz sulfide-bearing stage I and II evolved from initial high temperatures (near $360^{\circ}C$)to later lower temperatures(near $220^{\circ}C$)from lower salinity fluids(1.0 to 3.2 wt.% NaCl eq.). Fluid inclusion data from the post ore carbonate stage reflects much cooler($110^{\circ}$ to $180^{\circ}C$). Evidence of boiling indicates pressure of<85 bars, corresponding to depths of 400m to 1050m assuming lithostatic and hydrostatic loads. Au-deposition was likely a result of boiling, coupled with declining temperatures. The ${\delta}^{34}S$ $H_2S$ values calculated for sulfides are consistent with an igneous source of sulfur with a ${\delta}^{34}S_{{\Sigma}S}$ value near 4.0‰.

• 자원환경지질
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• 제24권4호
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• pp.347-361
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• 1991

The Sangeun ore deposit is located in a volcanic belt within the Gyeongsang Basin in south western Korea. The ore deposit is of representative epithermal Au-Ag quartz vein type developed in lapilli tuff. This paper presents the mineralization with special emphasis on mineral zoning of the deposits. Principal points are summarized as follows: (1) Four stages of mineralization are recognized based on macrostructures. From ealier to later they are stage I(arsenopyrite-pyrite-quartz), stage II(Au-Ag bearing Pb-Zn-quartz), stage III(barren quartz), and stage IV(dickite-quartz). (2) Electrum principally occurs with arsenopyrite and galena in stage II, and has chemical compositions of 72.9-67.1 Ag atom %, and has Ag/Au ratio of 2.69-2.04. (3) Sphalerite varies in its FeS content according to the mineralization stages; 22.03-18.60 mole % FeS and 1.33-0.23 mole % MnS in stage IB, 16.11-8.64 mole % FeS and 1.33-0.23 mole % MnS in stage II. (4) Alteration zones of mineral assemblage, from the vein to the wall-rock, consist of sericite - quartz - pyrite, sericite - quartz - dickite, sericite - chlorite plagioclase respectively.

• 자원환경지질
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• 제30권1호
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• pp.15-23
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• 1997

Gold mineralization of the Ogkye gold mine was deposited mainly in quartz veins up to 150 cm wide which occupy fissures in Cambrian Pungchon limestone. Ore minerals are relatively simple as follows: pyrite, arsenopyrite, pyrrhotite, sphalerite, electrum and galena. On the basis of the Ag/Au ratio on ore grades, mode of occurrence and assoicated mineral assemblages, the Ogkye gold deposit can be classified as pyrite-type gold deposit (Group IIB). Fluid inclusion data indicate that ore minerals were deposited between $400^{\circ}$and $230^{\circ}C$ from relatively dilute fluids (0.2 to 7.3 wt.% eq. NaCl) containing $CO_2$. The ore mineralization resulted from a complex history of $CO_2$ effervescence and local concomitant boiling coupled with cooling and dilution of ore fluids. Gold deposition was likely a result of decrease of sulfur activity caused by sulfide deposition and/or $H_2S$ loss accompanying fluid unmixing. Sulfur isotope compositions of sulfide minerals (${\delta}^{34}S=3.5{\sim}5.9$‰) are consistent with ${\delta}^{34}S_{H_2S}$ value of 4.8 to 6.1‰, suggesting mainly an igneous source of sulfur partially mixed with wall-rock sulfur.

• 자원환경지질
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• 제13권4호
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• pp.205-213
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• 1980

Stannite is mainly found in hypothermal ore deposits, whereas mawsonite and stannoidite occur characteristically with bornite and chalcopyrite in subvolcanic (xenothermal) ore deposits. Mawsonite always shows the replacement on the rims of stannoidite grains or along the grain boundaries of stannoidite, bornite and chalcopyrite. In the Tada mine, Japan, the following mineral assemblages of the Cu-Fe-Sn-S minerals were observed. 1) bornite-stannoidite; 2) stannoidite-chalcopyrite; 3) stannite-chalcopyrite; 4) bornite-mawsonite-stannoidite; 5) bornite-stannoidite-chalcopyrite; 6) mawsonite-stannoidite-chalcopyrite; 7) stannoidite-stannite-chalcopyrite; 8) bornite-mawsonite-stannoidite-chalcopyrite The heating and D.T.A. experimental results indicate that natural stannoidite containing 3 weight percent of zinc decomposes to bornite, stannite and chalcopyrite at above $500^{\circ}C$, whereas zinc-free synthetic stannoidite is stable up to $800^{\circ}C$. The stability temperature of zincian stannoidite depends on the zinc content. Mawsonite is stable at temperatures below $390^{\circ}C$ and decomposed to stannoidite, bornite and chalcopyrite above it. According to the sulfur fugacity determination by the electrum tarnish method the univariant assemblage of mawsonite, bornite, stannoidite and chalcopyrite requires a higher sulfur fugacity than that of bornite, stannoidite and chalcopyrite assemblage.