• Economic and Environmental Geology
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• v.46 no.2
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• pp.153-163
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• 2013

The Ogcheon Au-Ag deposit consists of two quartz veins that fill the NE or NW-trending fissures in the metasedimentary rocks of unknown age. The quartz veins occur mainly in the massive type with partially breccia and cavity. They can be found along the strike for about minimum 50 m and varied in thickness from 0.1 to 0.3 m. The mineralogy of quartz veins from the Ogcheon deposit is mainly composed of hydrothermal alteration minerals such as pyrite, quartz, sericite, chlorite, clay minerals and sulfides including pyrite, pyrrhotite, arsenopyrite, sphalerite, chalcopyrite and galena. Fluid inclusion data from quartz indicate that homogenization temperatures and salinity of mineralization range from 184 to $362^{\circ}C$ and from 0.0 to 6.6 wt.% eq. NaCl, respectively. These suggest that ore forming fluids were progressively cooled and diluted from mixing with meteoric water. Sulfur(${\delta}^{34}S$: 0.4~8.4‰) isotope composition indicates that ore sulfur was derived from mainly magmatic source although there is a partial derivation from the host rocks. The calculated oxygen(${\delta}^{18}O$: 4.9~12.1‰) and hydrogen(${\delta}D$: -92~-74‰) isotope compositions suggest that magmatic and meteoric ore fluids were equally important for the formation of the Ogcheon deposit and then overlapped to some degree with another type of meteoric water during mineralization.

• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.115-124
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• 2007

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.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.331-342
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• 2009

Groundwater samples were collected from the bedrock aquifers related with Okcheon metasedimentary rocks. Arsenic (As) concentrations in the samples varied between 0.0051 and 0.887 mg/L, with an average of 0.0248. Cations and anions of groundwaters had no relationship with As contents as well as with spatial distribution of geology in the area. Pyrite, chalcopyrite and arsenopyrite in the core samples of the monitoring wells were identified in thin section, X-ray diffraction (XRD) and electron probe microscope analysis (EPMA). It was suggested that these minerals are responsible for the As in groundwater. The groundwater showed saturations with respect to calcite $(CaCO_3)$, dolomite (CaMg$(CO_3)_2$) and Magnesite $(MgCO_3)$. $HAsO_4{^{2-}}$ activities in the groundwater samples were close to $Ca_3(AsO_4)_2(c)$ and $Mn_3(AsO_4)_2(c)$ solubility isotherms, indicating that the maximum As contents in groundwater are secondly controlled by the precipitation and dissolution of carbonate minerals due to alkaline and oxic nature of the groundwater (pe+pH>10).

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.413-428
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• 2010

The Gukjeon Pb-Zn mine was recognized as skarn deposits which replaced the limestone layer of the Jeongkansan Formation by intrusion of biotite granite in late Cretaceous. The Jeongkansan Formation is mainly composed of tuffaceous shale, and interlayers of sandstone, andesitic tuff, limestone, and conglomerate. The limestone layer is located in the lower part of the Jeongkansan Formation with 6~8 m in thickness and about 500 m in length. The Gukjeon deposits are divided into the Jukgang ore bodies once mined underground and the eastern ore bodies. Main ores are sphalerite and galena, in association with small amounts of chalcopyrite, arsenopyrite, pyrite, and pyrrhotite, etc. Skarns mainly consist of clinopyroxenes and Ca-garnets, associated with actinolite, chlorite, axinite, and calcite, etc. The Jukgang ore bodies show symmetrical distribution of zoning outward, representing clinopyroxene (hedenbergite) zone, clinopyroxene-garnet (grossular) zone, garnet (andradite) zone, and alteration zone of hornfels. $Fe^{2+}$ contents in clinopyroxenes increase with decreasing sphalerite grade. Sphalerite ores are found in all zones and $Fe^{2+}$ contents in sphalerite increase in the same way as those in clinopyroxenes, implying that clinopyroxene and sphalerite are closely related each other. It is concluded that the Gukjeon ores occurred in the ore rich zone of high grade sphalerite with less pyrite in assoication with clinopyroxene.

• Economic and Environmental Geology
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• v.34 no.2
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• pp.157-166
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• 2001

Numerous base-metal bearing hydrothermal quartz vein deposits occur in the Hunan province of southern China. The Tangguanpu lead-zinc-tin-silver mine is the major producer among these deposits. Lead-zinc-tin-silver mineralization occurs in a single stage of massive quartz veins which filled fractures in fault zones within Paleozoic metasedimentary rocks. Sphalerite, chalcopyrite, galena, pyrite, arsenopyrite and pyrrhotite are the principal sulphide minerals in the Tangguanpu lead-zinc ores with minor amounts of tin- and antimony-bearing sulphides (stannite, teallite, boulangerite and tetrahedrite). Based on the iron and zinc partitioning between coexisting stannite and sphalerite, the formation temperature for this mineral assemblage range from 300$^{\circ}$ to 330$^{\circ}$C, which relatively agree with the upper part of homogenization temperature of fluid inclusion in quartz (20T-358$^{\circ}$C). Fluid inclusion data show that main lead-zine-tin-silver mineralization occurred from $H_{2}O$-NaCl fluids with relatively low salinities (11.2-7.3 wl.% eg. NaCI) at temperatures between 207$^{\circ}$ and 358$^{\circ}$C. The relationship between homogenization temperature and salinity suggests a history of cooling and dilution followed by initial boiling. Evidence of initial fluid boiling may indicate the fluid trapping pressures of 180 bars. The ${\delta}^{34}S{{\Sigma}S}$ values of -5.0 to 1.1 %, indicate an igneous source of sulfur in the Tangguanpu lead-zinc-tin-silver hydrothermal fluids.

• Economic and Environmental Geology
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• v.31 no.2
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• pp.111-125
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• 1998

Dispersion, migration and enrichment of environmental toxic elements from the Samkwang Au-Ag mine area were investigated based upon major, minor and rare earth element geochemistry. The Samkwang mine area composed mainly of Precambrian granitic gneiss. The mine had been mined for gold and silver, but closed in 1996. According to the X-ray powder diffraction, mineral composition of stream sediments and soils were partly variable mineralogy, which are composed of quartz, orthoclase, plagioclase, amphibole, muscovite, biotite and chlorite, respectively. Major element variations of the host granitic gneiss, stream sediments and soils of mining and non-mining drainage, indicate that those compositions are decrese $Al_2O_3$, $Fe_2O_3$, MgO, $TiO_2$, $P_2O_5$ and LOI with increasing $SiO_2$ respectively. Average compositional ranges (ppm) of minor and/or environmental toxic elements within those samples are revealed as As=<2-4500, Cd=<1-24, Cu=6-117, Sb=1-29, Pb=17-1377 and Zn=32-938, which are extremely high concentrations of sediments from the mining drainage (As=2006, Cd=l1, Cu=71, Pb=587 and Zn=481 ppm, respectively) than concentrations of the other samples and host granitic gneiss. Major elements (average enrichment index=6.53) in all samples are mostly enriched, excepting $SiO_2$, $Na_2O$ and $K_2O$, normalized by composition of host granitic gneiss. Rare earth element (average enrichment index=2.34) are enriched with the sediments from the mining drainage. Minor and/or environmental toxic elements within all samples on the basis of host rock were strongly enriched of all elements (especially As, Br, Cu, Pb and Zn), excepting Ba, Cr, Rb and Sr. Average enrichment index of trace elements in all samples is 15.55 (sediments of mining drainage=37.33). Potentially toxic elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) of the samples revealed that average enrichment index is 46.10 (sediments of mining drainage=80.20, sediments of nonmining drainage=5.35, sediments of confluent drainage=20.22, subsurface soils of mining drainage=7.97 and subsurface soils of non-mining drainage=4.15). Sediments and soils of highly concentrated toxic elements are contained some pyrite, arsenopyrite, sphalerite, galena and goethite.

• Economic and Environmental Geology
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• v.44 no.3
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• pp.193-201
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• 2011

The Geopung Cu deposit consists of two subparallel quartz veins that till the NE-trending fissures in Triassic Cheongsan granite. The quartz veins occur mainly massive with partially cavity and breccia. They can be followed along strike for about 500 m and varies in thickness from 0.2 to 2.2 m. Based on the mineralogy and paragenesis of veins, mineralization of quartz veins can be divided into hypogene and supergene stages. Hypogene stage is associated with hydrothermal alteration minerals such as sericite, pyrite, quartz, chlorite, clay minerals and sulfides such as pyrite, arsenopyrite, pyrrhotite, marcasite, sphalerite, stannite, chalcopyrite and galena. Supergene stage is composed of geothite. Fluid inclusion data from quartz indicate that homogenization temperatures and salinity of hypogene stage range from 163 to $356^{\circ}C$ and from 0.2 to 7.2 wt.% eq. NaCl, respectively. They suggest that ore forming fluids were progressively cooled and diluted from mixing with meteoric water. Sulfur (${\delta}^{34}S$: 4.3~9.2‰) isotope composition indicates that ore sulfur was derived from mainly magmatic source although there is a partial derivation from the host rocks. The calculated oxygen (${\delta}^{18}O$: 0.9~4.0‰) and hydrogen (${\delta}D$: -86~-69‰) isotope compositions suggest that magmatic and meteoric ore fluids were equally important for the formation of the Geopung Cu deposit and then overlapped to some degree with another type of meteoric water during mineralization.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.171-181
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• 2022

The Geochang Au-Ag deposit is located within the Yeongnam Massif. Within the area a number of hydrothermal quartz and calcite veins were formed by narrow open-space filling of parallel and subparallel fractures in the granitic gneiss and/or gneissic granite. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz vein; stage II, barren calcite vein) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages (early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of pyrite with minor pyrrhotite and arsenopyrite; middle, characterized by introduction of electrum and base-metal sulfides with minor sulfosalts; late, marked by hematite with base-metal sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥380℃ ) and later lower temperatures (≤210℃ ) from H₂O-CO₂-NaCl fluids with salinities between 7.0 to 0.7 equiv. wt. % NaCl of Geochang hydrothermal system. The relationship between salinity and homogenization temperature indicates a complex history of boiling, fluid unmixing (CO₂ effervescence), cooling and dilution via influx of cooler, more dilute meteoric waters over the temperature range ≥380℃ to ≤210℃. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Geochang hydrothermal system with increasing paragenetic time. The Geochang deposit may represents a mesothermal gold-silver deposit.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.753-765
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• 2021

The Dongwon Au-Ag deposit is located within the Paleozoic Taebaeksan province, Okcheon belt. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz veins; stage II, barren carbonate veins) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages(early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of pyrite with minor magnetite, pyrrhotite and arsenopyrite; middle, characterized by introduction of electrum and base-metal sulfides with minor sulfosalts; late, marked by argentite, Cu-As (and/or Sb) and Ag-Sb sulfosalts with base-metal sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥430℃) and later lower temperatures (≤230℃) from fluids with salinities between 6.0 to 0.4 wt. percent equiv. NaCl. The relationship of salinity and homogenization temperature suggest that ore mineralization at Dongwon was deposited mainly due to fluid boiling, cooling and dilution via influx of cooler, more dilute meteoric waters. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Dongwon hydrothermal system with increasing paragenetic time. The Dongwon deposit may represents a Korean-type and/or Au-Ag type mesothermal/epithermal gold-silver deposit.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.689-699
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• 2022

The Ssangjeon tungsten deposit is located within the Yeongnam Massif. Within the area a number of hydrothermal quartz veins were formed by narrow open-space filling of parallel and subparallel fractures in the metasedimentary rocks as Wonnam formation, Buncheon granite gneiss, amphibolite and/or pegmatite. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz vein; stage II, barren quartz vein) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages (early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of arsenopyrite with pyrite; middle, characterized by introduction of wolframite and scheelite with Ti-Fe-bearing oxides and base-metal sulfides; late, marked by Bi-sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥370℃) and later lower temperatures (≈170℃) from H₂O-CO₂-NaCl fluids with salinities between 18.5 to 0.2 equiv. wt. % NaCl of Ssangjeon hydrothermal system. The relationship between salinity and homogenization temperature indicates a complex history of boiling, fluid unmixing (CO₂ effervescence), cooling and dilution via influx of cooler, more dilute meteoric waters over the temperature range ≥370℃ to ≈170℃. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Ssangjeon hydrothermal system with increasing paragenetic time.