• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.211-217
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• 2010

A micro-focus X-ray computed tomography (CT) was employed to determine quantitative phase analysis of skarn Zn-Pb-Cu ore by nondestructive visualization of the internal mineral distribution of a skarn ore. The micro CT images of the ore were calibrated to remove beam hardening artifacts, and compared with its scanning electron microscope (SEM) images to set the threshold of CT number range covering sulfide ore minerals. The volume ratio of sulfide and gangue minerals was calculated 20.5% and 79.5%, respectively. The quantitative 3D X-ray CT could be applied to analyse the distribution of economic minerals and their recovery.

• Economic and Environmental Geology
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• v.19 no.spc
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• pp.3-17
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• 1986

Hundred mineral deposits including W-Mo, Pb-Zn-Cu, fluorite and talc occur in the Cambre-Ordovician limestone contacting with the Cretaceous Muamsa and Wolak granitoids in the Susanri-Hwanggangri mineralized zone. In most mineral deposits characterized by metasomatic replacement, skarn and hydrothermal vein types, two distinct tendencies were found as W-Mo mineralization in or/and near granitoid batholith and ($Pb-Zn-Cu(CaF_2)$) mineralization which is gradually increased toward the batholith. W-Mo veins of extensive vein system occupy northly striking fractures whilst $Pb-Zn-Cu-CaF_2$ veins strike northeast or northwest. In this work, three representative lead-zinc-copper deposits choosing the Dangdu, Useog and Eoksu mines were dealt with in detail. Skarn ore bodies in the Dangdu mine were grouped into early diopside rich clinopyoxene-garnet, barren skarn and ore bearing late hedenbergite rich clinopyroxene-garnet skarn. Temperature and $X_{CO_2}$, obtained from hedenbergite-andradite-calcite-quartz mineral equilibria in the Dangdu ore deposits were $580{\sim}650^{\circ}C$ and 0.15~0.3, respectively. Fluid inclusien evidence in the Useog mine indicates that main stage mineralization temperature ranges from 224 to $389^{\circ}C$ with a salinity of 2~17 equivalent wt. percent NaCl. Sphalerites from the Dangdu and Useog mines have 16~17.7 mole percent in FeS which is relatively consistent to those of some other lend-zinc ore deposits in South Korea. Filling tcmjCerature of fluid inclusion frem the Eoksu mine shows deposition of ore within the temperature ranges from 237 to $347^{\circ}C$ and within the salinity ranges from 2.6 to 10.77 equivalent wt. percent NaCl.

• Economic and Environmental Geology
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• v.31 no.5
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• pp.375-388
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• 1998

The purpose of this study is to investigate the ore genesis and occurrence of the Wondong polymetallic mineral deposits. The Pb-Zn, Fe and W-Mo mineralizations are found in skarn zones which formed mainly in or along the fault shear zones with the $N25-40^{\circ}W$ and $N10-50^{\circ}E$ directions, whereas the Cu-Mo mineralization is appeared hydrothermal replacement zone. The skarn minerals consist mainly of garnet and epidote, which were the last alteration phases between pneumatolytic and hydrothermal stages. The mineral paragenesis toward the late stage are as follows: arsenopyrite, scheelite, magnetite, pyrite, pyrrhotite, sphalerite, galena, chalcopyrite and molybdenite. Average ore grades are 0.33 g/t Au, 46.29 g/t Ag, 0.06% Cu, 4.4% Pb, 2.61% Zn and 29.39% Fe in tunnels, and 0.31 % Cu, 0.52% Pb, 6.29% Zn, 29.29% Fe, 0.03% Mo and 0.12% $WO_3$ in drill cores. Fluid inclusion data shows that Type I (liquid-rich), Type II (vapor-rich) and Type III (halite-bearing) inclusions are coexisted and their homogenization temperatures are quite similar. This indicates that boiling conditions have been reached during the mineralization. It is also likely that the ore solutions were evolved through the mixing between magmatic and meteoric waters. Rhyolite and quartz porphyry far the mineralization probably are not responsible of the Wondong polymetallic mineral deposits.

• Economic and Environmental Geology
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• v.48 no.1
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• pp.15-24
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• 2015

Extensive base-metal and/or gold bearing ore mineralizations occur in the Pacitan mineralized district of the south western portions in the East Java, Indonesia. Metallic ore bodies in the Pacitan mineralized district are classified into two major types: 1) skarn type replacement ore bodies, 2) fissure filling hydrothermal ore bodies. Skarn type replacement ore bodies are developed typically along bedding planes of limestone as wall rock around the quartz porphyry and are composed mineralogically of skarn minerals, magnetite, and base metal sulfides. Hydrothermal ore bodies differ mineralogically in relation to distance from the quartz porphyry as source igneous rock. Hydrothermal ore bodies in the district are porphyry style Cu-Zn-bearing stockworks as proximal ore mineralization and Pb-Zn(-Au)-bearing fissure filling hydrothermal veins as distal ore mineralization. Sulfur isotope compositions in the sulfides from skarn and hydrothermal ore bodies range from 6.7 to 8.2‰ and from 0.1 to 7.9‰, respectively. The calculated ${\delta}^{34}S$ values of $H_2S$ in skarn-forming and hydrothermal fluids are 0.9 to 7.1‰ (5.6-7.1‰ for skarn-hosted sulfides and 0.9-6.8‰ for sulfides from hydrothermal deposits). The change from skarn to hydrothermal mineralization would have resulted in increased $SO_4/H_2S$ ratios and corresponding decreases in ${\delta}^{34}S$ values of $H_2S$. The calculated ${\delta}^{18}O$ water values are: skarn magnetite, 9.6 and 9.7‰; skarn quartz, 6.3-9.6‰; skarn calcite, 4.7 and 5.8‰; stockwork quartz, 3.0-7.7‰; stockwork calcite, 1.2 and 2.0‰; vein quartz, -3.9 - 6.7‰. The calculated ${\delta}^{18}O_{water}$ values decrease progressively with variety of deposit types (from skarn through stockwork to vein), increasing paragenetic time and decreasing temperature. This indicates the progressively increasing involvement of isotopically less-evolved meteoric waters in the Pacitan hydrothermal system. The ranges of ${\delta}D_{water}$ values are from -65 to -88‰: skarn, -67 to -84‰; stockwork, -65 and -76‰; vein, -66 to -88‰. The isotopic compositions of fluids in the Pacitan hydrothermal system show a progressive shift from magmatic hydrothermal dominance in the skarn and early hydrothermal ore mineralization periods toward meteoric hydrothermal dominance in the late ore mineralization periods.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.493-507
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• 2018

The Wooseok deposit in Jecheon belongs to the Hwanggangri Mineralized Distict of the northeastern Ogcheon Metamorphic Belt. Its geology consists mostly of limestone of the Choseon Supergroup and the Cretaceous Muamsa granite intruded at the eastern area of the deposit. The deposit shows vertical occurrence of skarn and hydrothermal vein ores with W-Mo-Fe and Cu-Pb-Zn mineralization and skarn is developed only at lower levels of the deposit. Skarn minerals are replaced or cut by ore minerals in paragenetic sequence of magnetite-hematite, molybdenite-scheelite-wollframite, and higher abundances of pyrrhotite-chalcopyrite-pyrite-sphalerite-galena. Garnet has chemical compositions of $Ad_{65.9-97.8}Gr_{0.3-32.0}Pyr_{0.9-3.0}$, corresponding to andradite series, and pyroxene compositions are $Hd_{4.5-49.7}Di_{42.3-93.9}Jo_{0.5-7.9}$, prevailing in diopside compositions, both of which suggest oxidized conditions of skarnization. On the FeS-MnS-CdS ternary diagram, FeS contents of sphalerite in vein ores decrease with increasing MnS contents from bottom to top levels, possibly relating to W mineralization in deep and Pb-Zn mineralization in shallow level. Sulfur isotope values of sulfide minerals range from 5.1 to 6.8‰, reflecting magmatic sulfur affected by host rocks. W-Mo skarn and Pb-Zn vein mineralization in the Wooseok deposit were established by spatio-temporal variation of decreasing temperature and oxygen fugacity with increasing sulfur fugacity from bottom to top levels.

• Journal of the Mineralogical Society of Korea
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• v.20 no.1 s.51
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• pp.35-46
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• 2007

Shinyemi skarn deposits occur as Fe-Mo skarn type and Pb-Zn-Cu hydrothermal replacement type along the contact between Cretaceous Shinyemi granitoids and Cambro-Ordovician mixed limestone and dolostone sequence of the Choseon Supergroup. In the lower part of Western Shinyemi ore body two stages of skarn formation have been observed: the early, stage I (magnesian) skarn with Fe mineralization and the late, stage II(calcic) skarn with Mo mineralization. The stage I skarn spatially is overprinted by stage II skarn. The stage I skarn is predominantly composed of olivine, magnetite and diopside whereas, the stage II skarn is dominated by hedenbergite and garnet. The skarnification process occurred in two stages, both prograde and retrograde for stage I and stage II skarns. In stage I, the prograde skarns, mainly composed of anhydrous silicate minerals, were formed at relatively higher temperatures (about $400\;to\;550^{\circ}C$) under low $CO_{2}$ fugacity ($X_{CO2}<0.1$) conditions. On the other hand, the retrograde skarns that consisted of hydrous minerals were formed at lower temperatures (about $300\;to\;400^{\circ}C$).

• Economic and Environmental Geology
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• v.13 no.3
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• pp.167-184
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• 1980

The granitic plutons associated with Ogcheon geosynclinal zone can be grouped into three different subzones; SE-Subzone for the migmatitic and schistose granites of the southeast margin, 101-181m.y. old; NW-Subzone for those of the northwest margin, 112-163m. y. old; and C-Subzone for those of central part of the zone, 63-183m.y. old. The intrusives in C-Subzone are further subdivided into the older, adamellite to granodiorite (148-183m.y. old) and the younger, perthitic granites (63-106m,y. old). The metallogenic distribution of South Korea suggests that, in the Ogcheon Zone, it is possible to delineate an elongated polymetallogenic province in the general orientation of the zone intimately related with the migmatite and plutonic zones mentioned. Moreover, the mineralization in the province was basically controlled by the patterns of local geology involving country rocks and related igneous bodies, that permit subdivision of the province into the following three parts: Northeast (NE) Province consists dominantly of thick Paleozoic calcareous sediments; Middle (M) Province is characterized by predominant argillaceous and partly calcareous sediments of Precambrian to Late Paleozoic age; and Southwest (SW) Province consisting mainly of volcanic and arenaceous sediments of Mesozoic age. The three different plutonic zones with three different country rock provinces above mentioned make a combination which consists of nine classes. Each class can be assumed to be characterized by specific mineralization type. In order to classify the mineralization types, the present study sampled twenty six ore deposits and mineralized areas in Ogcheon zone as shown figure 2; eight ore deposits from plutonic SE-Subzone, ten from the plutonic NE-Subzone and eight from the plutonic C-Subzone. The characteristics of the classes are as follows: NE-SE is predominant in Au-Ag vein and Sn-migmatite of katazonal occurrence; NE-C is most productive in Pb-Zn and remarkable in Fe contact deposit in mesozone and partly Pb-Zn-Cu skarn in limestone and subordinate in mesozone and partly Pb-Zn pipes; M-SE is considerable in Au-Ag vein and rare elements (Nb, Ta, etc.) of pegmatite; M-C is predominant in F-veins in epizone and Mo-W, Fe, Cu veins occur in replacement type; M-NW is productive in Fe metamorphic and skarn types, partly remarkable in Cu, Pb-Zn contact; SW-SE is barren in mineralization related to Jurassic igneous rocks; SW-C is predominant in alunite and pyrophyllite in tuffs; and SW-NW is scarece in Pb-Zn, Cu, As and Au-Ag veins.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.41-54
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• 1993

The Ulsan Fe-W deposit, which can be classified as a calcareous skarn deposit, is represented by ore pipe consisting principally of magnetite and lesser amounts of scheelite with minor sulphides, sulphosaits, arsenides, sulpharsenides, etc. At Ulsan mine, metasomatic processes of skarn growth may be divided broadly into two stages based on the paragenetic sequence of calc-silicate minerals and their chemical composition; early and late skarn stages. Early stage has started with the formation of highly calcic assemblages of wollastonite, diopsidic clinopyroxene and nearly pure grossular, which are followed by the formation of clinopyroxenes with salite to ferrosalite composition and grandite garnets with intermediate composition. Based on these calc-silicate assemblages, the temperatures of early skarn formations have been in the ranges of $550^{\circ}$ to $450^{\circ}$. The calc-silicate assemblages formed during the earlier half period of late skarn stage show the enrichment of notable iron and slight manganese, and the depletion of magnesium; clinopyroxenes are hedenbergitic, and grandite garnets are andraditic. The formation temperatures during this skarn stage are inferred to have been in the range of $430^{\circ}$ to $470^{\circ}C$ at low $X_{CO_2}$ by data from fluid inclusions of late andraditic garnets. The later half period of late skarn stage is characterized by the hydrous alteration of pre-existing minerals and the formation of hydrous silicates. The main iron-tungsten mineralization representing prominent deposition of magnetite immediately followed by minor scheelite impregnation has taken place at the middle of early skarn stage, while complex polymetallic mineralization has proceeded during and after the late skarn stage. Various metals and semimetals of Fe, Ni, Co, Cu, Zn, As, Mo, Ag, In, Sn, Sb, Te, Pb and Bi have been in various states such as native metal, sulphides, arsenides, sulphosaits, sulpharsenides and tellurides.

• Economic and Environmental Geology
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• v.20 no.3
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• pp.179-196
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• 1987

Various skarn ore deposits of Pb-Zn, Fe-Cu, W-Mo and others are widely distributed in the study area which consists mainly of Cambro Ordovician calcareous rocks. The ore deposits are all in close association with specific types of granitic rocks of mid-late Cretaceous age according to the kinds of ores: Fe-Cu deposit with granodiorite-quartz monzodiorite, Pb-Zn deposit with granite-granodiorite, W-Mo deposit with granite, and Mn deposit with quartz porphyry. The granitic rock of Fe-Cu deposit has lower content in K and higher in Ca than those of Pb-Zn deposits. On the contrary, the granitic rock of W-Mo deposit has much higher content in K and lower in Ca in comparison to those of Pb-Zn deposits. However, the granitic rock of Mn deposit shows similar variation to those of Pb-Zn deposits. Lithophile trace elements of Sr and Rb tend to vary in close relation with major elements of K and Ca, respectively. In good contrast, chalcophile elements of Cu, Pb, Zn, Wand Mo are enriched in the granitic rocks of their ore deposits, and other trace elements of Ni and Co show a trend to vary in relation with Mg, Fe and Cu, which have the same replacement index (0.14) as Ni and Co. Average K/Rb and Ca/Sr ratios of the granitic rocks range nearly within 300~150 and 150~40, respectively, and the distribution pattern of the ratios is different according to the kind of ore deposits: Fe-Cu deposit is plotted toward K-Rb poor region whereas Pb-Zn and W-Mo deposits toward K-Rb rich region. In contrast, Fe-Cu and Fe deposits are plotted toward Ca-Sr rich region whereas Pb-Zn deposit toward Ca-Sr poor region. The variation trend of chemical elements of the mid-late Cretaceous granitic rocks in the study area is similar to that of the Cretaceous granitic rocks in the Gyeongsang Basin. Therefore, this geochemical result may be applicable to determining what kinds of ore deposits a Cretaceous granitic rock is favourable for, and whether it is productive or non-productive for systematic geochemical exploration works.

• Economic and Environmental Geology
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• v.43 no.5
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• pp.477-490
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• 2010

The Gagok stratabound skarn deposit is the result of the intrusion of the Cretaceous granitic pluton into the Paleozoic calcareous rocks. The subvolcanic intrusion ranges in composition from quartz monzonite to granite porphyry with I-type, calc-alkaline and weakly peraluminous characteristics. Both endoskarn and exoskarn are developed at the Gagok Zn-(Pb) deposit, with more exoskarn than endoskarn. Geochemical and mineralogical characteristics in the Seongok and Wolgok orebodies can be treated in terms of self-organization. Sphalerites in the Gagok ore can also incorporate minor amounts of Mn, Cd, Cu and In. Trace element concentrations in different orebodies vary because fractionation of a given element into sphalerite is influenced by formation temperature and the amount of sphalerite in the ore. A group of high In/Zn and Cd/Zn ratios in ores, and low Mn/Fe ratios in sphalerites are correlated with proximal processes of a magmatic source. The pattern of minor/trace element variations in ores and sphalcrites can be used for petrogenetic interprctation, e.g., orebody zonation related to crystallization temperature and fluid d sources.