• Economic and Environmental Geology
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• v.18 no.2
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• pp.93-105
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• 1985

Whether a skarn deposit in carbonate host occurs in contact with certain igneous mass or not has been a general criterion in identifying the igneous rock that genetically relates to the skarn deposit. It is well known, however, that there are many skarn deposits which are not close to any given igneous contact but are far away from the contact. In this paper the reason why such deposits can be formed at a distance from the contact as mentioned is expressed based on the concept that skarn deposits and related igneous rocks are genetically connected at depth where ore-forming fluids emanate from magma and are removed upwards; the movement of ore-forming fluids separated from magma at any depth may have a tendency to infiltrate upward in bulk rather than to diffuse laterally; the paths of magma and cogenetic ore-forming fluids may be identical at lower depths but the latter can be diverted from the former with upward movement so that the positions of the skarn deposits which resulted from the ore-forming fludis at upper levels can be distant from the igneous contacts on a given horizontal section. Statistics indicate that the majority of exoskarns are found at distances up to 800 meters or rarely up to 3,000 meters from igneous contacts and endoskarns up to 600 meters or more. Numerous case studies of skarn deposits in various parts of the world support the above reasoning indicating a general downward convergency of skarn orebodies and related igneous masses with depth. A typical example of this situation is well demonstrated at the Keumseong molybdenum deposit, which is apart from the Jecheon granite on the surface but gets closer to the granite body with depth and finally is intertongued with the granite apophyses in its root zone. Another case for skarn deposit not associated with igneous contact either laterally or vertically but with a deep-seated distal igneous mass is the Sangdong scheelite deposit; 700 meters below the scheelite orebody a blind pluton of muscovite granite, which intruded into the Precambrian crystalline schist, has been recently discovered by deep drilling.

• 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.27 no.5
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• pp.423-440
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• 1994

The Samhwa iron ore deposit, which is of typical magnetite skarn type, is located in the Samhwadong area of Donghae city, Kangwon-do, Korea. Skarn minerals are mainly composed of garnet, clinopyroxene, vesuvianite, wollastonite and small amounts of epidote and quartz. The garnets are isotropic $(Ad_{92.82{\sim}98.37})$ or anisotropic andradite $(Ad_{45.30{\sim}75.85})$ and grossular $(Gr_{86.26{\sim}24.47})$, the clinopyroxenes are ferrosalite and salite, Homogenization temperature of gas rich two phase inclusions in garnet are $368{\sim}593^{\circ}C$, and salnities of polyphase inclusions in garnet have 33.9~68.4 equ. NaCl wt. %. Garnet grain often shows composional variation from its core to rim. In other words, Fe and Al contents in garnet vary inversely, which suggest that the variation depends upon $f_{o2}$ during skarn formation.

• Proceedings of the KSEEG Conference
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• 2002.04a
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• pp.344-346
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• 2002

• Geosciences Journal
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• v.22 no.6
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• pp.881-889
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• 2018

The Geodo skarn deposit is located in the Taebaeksan Basin, central eastern Korean Peninsula. The geology of the deposit consists of Cambrian to Ordovician calcareous sedimentary rocks and the Cretaceous Eopyeong granitoids. The skarns at Geodo occur around the Eopyeong granitoids, which consist, from early to late, of magnetite-bearing equigranular quartz monzodiorite, granodiorite, and dykes. These dykes emanated randomly from equigranular granodiorite and some of dykes spatially accompany skarns. Skarn Fe mineralization, referred as Prospect I and II in this study, is newly discovered beyond previously known skarns adjacent to the quartz monzodiorite. These discoveries show a vertical and lateral variation of skarn facies, grading from massive reddish-brown garnet-quartz in a lower and proximal zone to banded in an upper and distal zone, reflecting changes in lithofacies of the host rocks. Skarn veins in distal locations are parallel to sedimentary laminae, suggesting that lithologic control is important although proximal skarn has totally obliterated primary structures, due to intense retrograde alteration. Skarns at Geodo are systematically zoned relative to the causative dykes. Skarn zonation comprises proximal garnet, distal pyroxene, and vesuvianite (only in Prospect I) at the contact between skarn and marble. Retrograde alteration is intensely developed adjacent to the contact with dykes and occurs as modification of the pre-existing assemblages and progressive destruction such as brecciation of the prograde assemblages. The retrograde alteration assemblages consist predominantly of epidote, K-feldspar, amphibole, chlorite, and calcite. Most of the magnetite (the main ore mineral), replaces calc-silicate minerals such as garnet in the lower proximal exoskarn, whereas it occurs massive in distal pyroxene and amphibole in the upper and distal exoskarn. The emanation of dykes from the equigranular granodiorite has provided channelways for ascent of skarn-forming fluids from a deep source, whereas the style and nature of skarns suggest that originally structurally-controlled skarn-forming fluids may migrate long distances laterally to produce skarn in calcareous sedimentary rocks.

• 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.27 no.3
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• pp.135-147
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• 2014

This study analyzed spectroscopic methods for characterization of skarn minerals and sphalerite occurring in Dangdu ore deposit, and effectiveness of portable spectrometer in skarn mineral resources exploration is discussed. The spectroscopic analyses identified clinopyroxene, garnet, epidote, calcite, chlorite and sphalerite where spectral curves of clinopyroxene, garnet, epidote, and sphalerite show single mineral spectral characteristics and those of chlorite are in a mixed form with calcite and clinopyroxene. The assessment of spectroscopic analyses based on XRD analysis and microscopic observation reveals that clinopyroxene, garnet, epidote correspond well with more than 80% of detection, but sphalerite, chlorite, and calcite showed below 50% of detection rate. It is expected that skarn deposit exploration using a portable spectrometer is more effective in detection of clinopyroxene, garnet, and epidote whereas spectroscopic data of sphalerite, chlorite, and calcite needs to be utilized as a supplementary data. For the effective detection of chlorite and calcite, their content in the samples needs to be sufficient.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.153-153
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• 1999

• Economic and Environmental Geology
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• v.2 no.2
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• pp.53-67
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• 1969

Magnetite deposit of Pocheon Iron Mine is a contact replacement skarn deposit embedded in the carbonate rocks (limestone and dolomite) which are intruded by granite porphyry. The shape of ore bodies is sweet potato-like and/or irregular massive form; D-ore body, the biggest one is of $180m{\times}40m{\times}200m$ in size. The ore is in general of high grade. The location of the ore bodies is controlled by the fault which strikes north south and dips $60^{\circ}$ to $70^{\circ}$ to the west. A regular distribution of mineralized zones is recognized in order of outward (hanging wall side) from granite porphyry as follows: compact fine-grained skarn, limesilicates, magnetite ore body, marble, limesilicates, pyritized meta-sediments.

• Journal of the Mineralogical Society of Korea
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• v.26 no.3
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• pp.161-174
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• 2013

The geology of the weondong deposit area consists mainly of Cambro-Ordovician and Carboniferous-Triassic formations, and intruded quartz porphyry and dyke. The skarn mineralized zone in the weondong deposit is the most prospective region for the useful W-mineral deposits. To determine the skarn-mineralization age, U-Pb SHRIMP and K-Ar age dating methods were employed. The U-Pb zircon ages of quartz porphyry intrusion (WD-A) and feldspar porphyry dyke (WD-B) are 79.37 Ma and 50.64 Ma. The K-Ar ages of coarse-grained crystalline phlogopite (WD-1), massive phlogopite (WDR-1), phlogopite coexisted with skarn minerals (WD-M), and vein type illite (WD-2) were determined as $49.1{\pm}1.1$ Ma, $49.2{\pm}1.2$ Ma, $49.9{\pm}3.6$ Ma, and $48.3{\pm}1.1$ Ma, respectively. And the ages of the high uranium zircon of hydrothermally altered quartz porphyry (WD-C) range from 59.7 to 38.7 Ma, which dependson zircon's textures affected by hydrothermal fluids. It is regarded as the effect of some hydrothermal events, which may precipitate and overgrow the high-U zircons, and happen the zircon's metamictization and dissolution-reprecipitation reactions. Based on the K-Ar age datings for the skarn minerals and field evidences, we suggest that the timing of W-skarn mineralization in weondong deposit may be about 50 Ma. However, for the accurate timing of skarn mineralization in this area, the additional researches about the sequence of superposition at the skarn minerals and geological relationship between skarn deposits and dyke should be needed in the future.