• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.247-252
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• 2014

Gagok Mine, which is skarn deposits, includes sulfide minerals such as sphalerite, galena, chalcopyrite, and pyrrhotite. To explore these minerals, spectral induced polarization (SIP) is relatively effective compared to other geophysical exploration methods because there is a strong IP effect caused by electrode polarization. In the SIP, the chargeability related to sulfide mineral contents and the time constant related to the grain size of the minerals are obtained. For this reason, we aim to compare difference in the mineralized characteristics between two orebodies in the Gagok Mine by using the chargeability and the time constant. For this study, we sampled ores from the south of Wolgok orebody and the north of Sungok orebody. In order to recognize the mineralization characteristics, the metal content of the samples was measured by a potable XRF and the SIP data of the samples were acquired by using a laboratory SIP measurement system. As a result, the metals in the samples such as Pb, Zn, Cu, and Fe were detected by the portable XRF measurement. In particular, the Fe and Zn contents were far higher than the other metals. The Fe and the Zn were caused by the sphalerite and the pyrrhotite through microscopy. The Wolgok orebody had higher sulfide mineral contents than the Sungok orebody and the result corresponded with the chargeability result. However, we considered that the Sungok orebody had a larger sulfide mineral grain size than the Wolgok orebody because the time constant of the Sungok orebody was larger.

• Economic and Environmental Geology
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• v.32 no.3
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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.

• Economic and Environmental Geology
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• v.23 no.1
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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.

• Economic and Environmental Geology
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• v.30 no.1
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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.

• Economic and Environmental Geology
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• v.29 no.1
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• pp.11-21
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• 1996

The first Mg-skarn minerals are found from magnetite ore deposits of the Janggun mine, Korea. The skarn minerals are composed of mostly chondrodite, olivine， chlorite, serpentine, phlogophite, talc, apatite, magnesite， dolomite, siderite and trace amount of clinopyroxene, amphibole, garnet, wollastonite associated with magnetite, pyrrhotite and pyrite. The skarn zone is developed in the magnetite deposits at the contact of the Mg-rich Janggun Limestone Formation and the Chunyang granite. The chondrodites are columnar and radial shapes and some of them show twins. The chemical compositions of twinning-type chondrodites have high FeO (4.63 to 5.6 wt%), MnO (0.26 to 0.46 wt%) and low MgO (55.02 to 56.18 wt%) relative to the radial-type chondrodites. Twinning in chondrodite has been formed in close relation to substitution between Mg and Fe + Mn in humite solid solution. Temperature, $-logfo_2$ and $X_{CO2}$ during the skarn stage of magnetite deposits from the Janggun mine range from 395 to $430^{\circ}C$, from 30.5 to 31.2 atm and from 0.06 to 0.09, respectively.

• Economic and Environmental Geology
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• v.29 no.1
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• pp.1-11
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• 1996

Magnetite ores of the Janggun mine are embedded in dolomitic limestone of the Janggun Limestone Formation contacting with Chunyang granite, and are closely associated with skarn minerals. Mineralization of magnetite deposits can be divided into two stages as deep-seated skarn stage and shallow hydrothermal replacement stage. Mineralogies of skarn stage consist of magnetite, pyrrhotite and base-metal sulfides, and those of hydrothermal stage is base-metal sulfides, native bismuth, bismuthinite, tetrahedrite, boulangerite, bournonite and stannite. The FeS mole % in sphalerite and As atom % in arsenopyrite range from 22.47 to 26.30 and from 31.39 to 31.66 in skarn stage, and are from 17.54 to 32.54 and 28.87 to 30.70 in hydrothermal stage, respectively. Based on mineralization characteristics, mineral assemblages, chemical compositions and thermodynamic considerations, formation temperatures, sulfur fugacities ($-logf_2$), pH and oxygen fugacity ($-logfo_2$) estimated to be from 345 to $382^{\circ}C$, from 8.1 to 9.7atm, from 6.5 to 7.2 and from 30.5 to 31.2atm in the skarn stage, respectively, and temperature and $-logfs_2$ are from 245 to $315^{\circ}C$ and from 10.4 to 13.2atm in the hydrothermal stage.

• Economic and Environmental Geology
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• v.15 no.1
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• pp.1-16
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• 1982

Many skarn type iron ore deposits are distributed in Kimhae-Mulgeum area of Gyeongnam Province. Integrated field, mineralogic, geochemical and fluid inclusion studies were undertaken to illustrate the character and origin of the ores in this area. The iron ore deposits in this area are NS or NNE trending fracture filling magnetite veins which are developed in andesitic rocks near the contact with late Cretaceous micrographic granite bodies. Symmetrically zoned skarns are commonly developed in the magnetite veins of this area. Zoning of skarn from center to margin of the vein are as follows; garnet quartz skarn-epidote skarn-epidote orthoclase skarn-altered andesitic rocks. Major ore mineral is magnetite and small amount of hematite, pyrite, pyrrhotite, chalcopyrite and sphalerite are associated. Vein paragenesis reveals four depositional stages; 1) skarn stage, 2) iron sulfide and oxide stage, 3) skarn stage, 4) sulfide stage Minute halite-bearing polyphase inclusions and liquid inclusions are contained in quartz. Filling temperatures range from $257^{\circ}$ to $370^{\circ}C$.

• Economic and Environmental Geology
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• v.17 no.2
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• pp.91-100
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• 1984

The Gwangyang gold deposits geologically consist of granitic gneiss, metatectic gneiss and porphyroblastic gneiss which correspond to Jirisan gneiss complex. The formations of Gyeongsang system lies unconformably on these gneisses and are intruded by diorite, porphyritic andesite and Bulgugsa granites. Goheung districts are composed of quartz schist, andesitic rock, tuff and granite. The Gwangyang gold deposits are gold bearing fissure filling veins. The vein thickness varies from 15cm to 40cm and they consist of 7-10 layers in parallel. The Goheung copper deposits are sulphide bearing quartz veln which filled the fracture in andesitic rock and biotite granite. The contact zone of these rocks is partially altered. The mineral paragenesis of the Gwangyang and Goheung districts is pyrite, arsenopyrite, pyrrhotite, chalcopyrite, sphalerite, galena, sericite, quartz and calcite. The variation trends of FMA and A'KF triangular diagrams and the differentiation index (norm, Q + Or + Ab) versus oxides diagrams is similar to the Gyeonsang basin igneous rocks. From the trace element analysis of 10 samples of country rocks, wall rocks and veins, the distribution of copper and lead contents display a correlative distribution pattern in relation to gold and silver. Homogenization temperature of fluid inclusions range from $200^{\circ}C$ to $270^{\circ}C$ in quartz from the Gwangyang gold vein and the size of fluid inclusion range from 0.01mm to 0.04mm. The fluid inclusions are mainly one or two phase and the filling degree of the inclusions varies from 85 to 95.

• Economic and Environmental Geology
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• v.20 no.4
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• pp.261-271
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• 1987

Muguk gold deposits are composed of quartz veins emplaced along faults in Mesozoic granodiorite. General strikes and dips of the veins are $N15{\sim}20^{\circ}W$ and $70{\sim}80^{\circ}NE$. Associated ore minerals are pyrite, arsenopyrite, sphalerite, galena, chalcopyrite, pyrrhotite, native silver, argentite, tetrahedrite and electrum. Vein mineral paragenesis is complicated by repeated fracturing, but five distinct depositional stages can be recognized. Electrum grains are associated mainly with sulfide bands formed along both margins of pale pink quartz of stage 3, and with patches of pyrite aggregate of stage 4. Before the close down in 1972, Muguk gold mine yielded more than 8 tons of gold of which major portion was produced from the No.2 vein. No.2 vein, extending about 1,500m laterally, was exploited to a depth of about 750m. In 1984, Young-poong mining company acquired the mining property and began geologic mapping, geochemical and geophysical exploration, diamond drilling and exploration tunnelling around the mine area to seek for other rich gold-bearing quartz veins. As the Samhyungje vein was disclosed to be the most rich vein, exploration works were focussed on the Samhyungje vein. As of August 1987, 22,338m of diamond drilling and 9,652m of exploration tunnelling have been undertaken. Owing to the successful result of exploration, the Muguk mine commenced normal operation on January 1987, treating 5,500 tons of ore per month.

• Economic and Environmental Geology
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• v.7 no.2
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• pp.63-78
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• 1974

Daehwa tungsten-molybdenum deposits is fissure filled quartz veins occurring in Precambrian granite gneiss adjacent to the contact with Mesozoic biotite granite mass. Essential ore minerals are molybdenum and wolframite accompaning scheelite, cassiterite, chalcopyrite, pyrrhotite, pyrite and bismuthinites. Gangue minerals are quartz and little muscovte, fluorite, beryl and Carbonate minerals. Fluid inclusions in quartz, fluorite, beryl, scheelite and calcite have filling temperature ranges of $170-353^{\circ}C$. According to the studies of mineral paragenesis and filling temperature of fluid inclusion indicate that main tungsten and molybdnum mineralization have taken place with the minerals whose filling temperature ranges 205 to $353^{\circ}C$. Liquid $CO_2$ bearing fluid inclusions are characteristic in the quartz and early fluorite of tungsten and tungsten bearing molybdenum veins but hardly recognized from molybdemun veins. Estimated $CO_2$ concentration according to diagram proposed by the Takenouchi ranges from 10 to 20wt%. These facts suggest that tungsten mineralization may be related to the $CO_2$ content of the hydrothermal solution during the mineralizing period.