• Economic and Environmental Geology
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• v.16 no.1
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• pp.37-49
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• 1983

The skarn type tungsten deposits are developed in the contact aureole of Jurassic biotite-hornblende granodiorite and limestone beds. The latter can be divided into the Great Limestone Series of Joseon System and Gabsan Formation which is correlative to the Hongjeom Series of Pyeongahn System. The skarns are impregnated in the limestone, sandstone, schist and granodiorite, and showing zonal distribution. The five skarn zones are from fresh limestone inwards to wollastonite-skarn, clinopyroxene-skarn, clinopyroxene-garnet skarn, garnet skarn and vesuvianite skarn zone. The ore mineral, scheelite, disseminates in the clinopyroxene-garnet and vesuvianite skarn zone, and the size of the scheelite crystals in vesuvianite skarn zone is larger than in clinopyroxene- garnet skarn zone. According to the mineral paragenesis and the composition of skarn minerals, oxygen fugacity ($fo_2$) is low. Fluid inclusions in quartz comprise much $LCO_2$ and fluid inclusion studies revealed that the homogenization temperatures range $240-290^{\circ}C$.

• Economic and Environmental Geology
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• v.18 no.3
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• pp.205-216
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• 1985

Fluid inclusion study reveals that the mineralogical zonal distribution of the Sangdong skarn orebody may be likely related to (homogenization) temperatures of fluids with time and spaces. Firstly limestone beds were replaced by hot boiling fluids ranging from 350 to $550^{\circ}C$ and formed the pyroxene-garnet skarn, which was replaced into the amphibole and the quartz-mica skarns by non-boiling fluids at 300 to $500^{\circ}C$, mainly penetrated the central part of the pyroxene-garnet skarn orebody. Freezing tests identify presence of $CaCl_2$ and $MaCl_2$ as brines in the fluids besides NaCl and KCL that are shown as daughter minerals and show that two or more fluids be involved in mineralization by showing a bimodal distribution of salinities. This study has contributed to find a new orebody and a granitic pluton as a source rock.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.517-535
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• 2007

Two distinctive Mesozoic hydrothermal systems occurred in South Korea: the Jurassic/Early Cretaceous(ca. $200{\sim}130$ Ma) deep-level ones during the Daebo orogeny and the Late Cretaceous/Tertiary(ca. $110{\sim}45$ Ma) shallow hydrothermal ones during the Bulgugsa event. The Mesozoic hydrothermal system and the metallic mineralization in the Korean Peninsula document a close spatial and temporal relationship with syn- to post-tectonic magmatism. The calculated ${\delta}^{18}O_{H2O}$ values of the ore-forming fluids from the Mesozoic metallic mineral deposits show limited range for the Jurassic ones but variable range for the Late Cretaceous ones. The orogenic mineral deposits were formed at relatively high temperatures and deep-crustal levels. The mineralizing fluids that were responsible for the formation of theses deposits are characterized by the reasonably homogeneous and similar ranges of ${\delta}^{18}O_{H2O}$ values. This implies that the ore-forming fluids were principally derived from spatially associated Jurassic granitoids and related pegmatite. On the contrary, the Late Cretaceous ferroalloy, base-metal and precious-metal deposits in the Taebaeksan, Okcheon and Gyeongsang basins occurred as vein, replacement, breccia-pipe, porphyry-style and skarn deposits. Diverse mineralization styles represent a spatial and temporal distinction between the proximal environment of subvolcanic activity and the distal to transitional condition derived from volcanic environments. The Cu(-Au) or Fe-Mo-W deposits are proximal to a magmatic source, whereas the polymetallic or the precious-metal deposits are more distal to transitional. On the basis of the overall ${\delta}^{18}O_{H2O}$ values of various ore deposits in these areas, it can be briefed that the ore fluids show very extensive oxygen isotope exchange with country rocks, though the ${\delta}D_{H2O}$ values are relatively homogeneous and similarly restricted.

• 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.32 no.5
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• pp.537-544
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• 1999

In mineral exploration, there are many data sets which need to be created, processed and analyzed in order to discover a favorable mineralized zone. Recently, with Geographic Information System (GIS), such exploration data sets have been able to be systematically stored and effectively processed using computer technologies. In this study, most exploration data sets were first digitized and then rasterized. Furthermore, they were integrated together by using fuzzy set theory to provide a possibility map toward a target hypothesis. Our target hypothesis is "there is a skarn magnetite deposit in this study" and all fuzzy membership functions were made with respect to the target hypothesis. Test area is extended from 37:00N/l28:30E to 37:20N/I28:45E, approximately 20 km by 40 km. This area is a part of Taebaeksan mineralized areas, where the Sinyemi mine, a skarn magnetite deposit, is located. In final resultant map, high potential or possibility area coincides with the location of the Shinyemi mine. In this regard, we conclude the fuzzy set theory can be effectively applied to this study and provides an excellent example to define potential area for further mineral exploration.

• Economic and Environmental Geology
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• v.49 no.3
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• pp.193-199
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• 2016

Constancia mine is a deposit developed within Andahuaylas-Yauri Cu-Mo-Au metallogenic belt, southeastern Peru and is located in the southwestern part of Abancay deformation zone structurally as the porphyry copper deposit type. Mineralized zone in Constancia mine are composed of leached zone, secondary enrichment zone(ca. 1% Cu), mixed zone, primary mineralized zone(ca. 0.5%), skarn zone(ca. 1.5% Cu) from the upper part. Main country rock is monzonitic porphyry. Leached zone are characterized by the precipitation of limonite and looks brown in the outcrop. Oxidized zone have green due to the occurrence of copper oxide and secondary enrichment zone are characterized by the occurrence of chalcocite. Skarn zone are characterized by the occurrence of magnetite and garnet. Now, Hudbay, Canadian mining company, have 100% share about Constancia mine and started to produce commercially from January, 2015.

• Economic and Environmental Geology
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• v.44 no.5
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• pp.345-357
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• 2011

It was carried out to the survey on the lead-zinc and tungsten occurrences in the Kau Loc mineralized belt within northern Vietnam. The lead-zinc occurrence bear the ore body parallel to the bedding of limestone formation. Assuming the surface grade and geological reserve, Pb+Zn deposit is estimated to the small to medium-sized ore deposit. On the other hand, considering the distribution of small-scale stock intruding the Devonian limestone, it is thought that the tungsten occurrence has the proper geological conditions anticipating the presence of skarn mineralization. However, there is no evidence to recognize economic feasibility in the present situation because of the absence of detailed geology and ore deposit survey on the tungsten occurrence.

• 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.

• Journal of the Mineralogical Society of Korea
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• v.4 no.2
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• pp.119-128
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• 1991

In the southern limb of the Hambaek geosyncline belt, large-scaled skarn deposits are developed in the Cambro-Ordovician sedimentary rocks of the Chosun Supergroup. They are the Sangdong tungsten deposit, Geodo iron-copper deposit, Yeonhwa I and II lead-zinc deposits, and Ulchin zinc-lead deposit, all of which are associated with various skarn minerals. Though different occurrences and paragenesis are found in different deposits, most skarn deposits always have skarns of garnet (andradite-grossular series) and clinopyroxene(heden-bergite-diopside series). Andradite and hedenbergite are Fe-dominant members, but show different oxidation states, that is, Fe3+ for andradite and Fe2+ for hedenbergite. According to iron chemistry and log([Fe/Al]gd/[Fe/Mg]cpx) derived from equilibrium reactions, the diopside-andradite and hedenbergite-grossular pairs suggest the oxidized state (dian type) and reduced state (hegro type), respectively. Among skarn deposits developed in the Hambaek geosynline, it can be classified that the Geodo and Yeonhwa I skarns are of dian type, while the Sangdong, Yeonhwa II, and Ulchin deposits are of hegro type. This classification is not applicable to all kinds of skarn deposits, but may be applicable to such deposits as are more controlled by oxygen fugacity than composition of skarn fluid.

• Economic and Environmental Geology
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• v.50 no.1
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• pp.73-83
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• 2017

The surveyed mines are located in a polymetallic vein, replacement, and skarn mineral district in the central Andes of Peru. Iscaycruz, which includes underground and open pit mines that produce zinc and lead concentrates, was the largest mineral deposit of an important group of base metal deposits in the Andes of central Peru. The deposits are sub-vertical seams of polymetallic ores(Zn, Cu, and Pb). These seams are hosted by Jurassic and Cretaceous sedimentary rock formation. The intrusion of igneous rocks in these formations originated metallic deposits of metasomatic and skarn types. The Raura mine is composed of polymetallic deposit of veins and replacement orebodies. The main sedimentary unit in the area is Cretaceous Machay Limestone. The Raura depression contains several orebodies each with different mineralization: predominantly Pb-Zn bearing Catuvo orebody; Ag-rich galena-bearing Lake Ninacocha orebody; Cu-Ag bearing Esperanza and Restauradora orebody. Huaron is a hydrothermal polymetallic deposit of silver, lead, zinc, and copper mineralization hosted within structures likely related to the intrusion of monzonite dikes, principally located within the Huaron anticline. Mineralization is encountered in veins parallel to the main fault systems, in replacement bodies known as "mantos" associated with the calcareous sections of the conglomerates and other favourable stratigraphic horizons, and as dissemination in the monzonitic intrusions at vein intersections.