• Economic and Environmental Geology
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• v.23 no.4
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• pp.369-381
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• 1990

Most of significant ore deposits in South Korea such as the Sangdong W - Mo, the Yeonhwa Pb-Zn and the Geodo Cu-Fe skarn ore deposits occur at the southern limb of the Hambaeg syncline in the Taebaeg Basin. The mineralization took place in the interbedded limestone of the Myobong Formation and the Pungchon limestone of the Great Limestone Group of the Cambrian age, generally striking E-W and dipping 25-30 degrees north. There are no outcrops of the skarn-type orebody at the northern limb of the syncline. In order to find a clue of a possible hidden orebody localized at the limestones in the northern limb, a lithogeochemical exploration by using carbon isotope and some elements such as Si, Ca, Fe and Al at the Sangdong Mine area has been attempted as for a modelling study. For this study, 45 samples from the Pungchon limestone which do not show any megascopic indication of mineralization have been taken in both the mineralized zone and the unminerallized zone at the Sangdong Mine area. Analytical data show that there are big differences in the contents of CaO and $Al_2O_3$ between the Pungchon limestone of the mineralized zone and that of the unmineralized zone. Carbon isotope data exhibit that ${\delta}^{13}C$ values of the Pungchon limestone in the mineralized zone are highter than those in the unmineralized zone. The difference in the analytical values of CaO, $Al_2O_3$ and the carbon isotope between the mineralized and the unmineralized zones is as follows ; Unminerallized zone Mineralized zone CaO 51.3% 43.5% $Al_2O_3$ 0.6% 2.4% ${\delta}^{13}C$ -0.39 permil -0.56 permil $Fe_2O_3$ 0.9% 1.4% $SiO_2$ 3.0% 2.4% The decrease in the Si content of the Pungchon limestone in the mineralized zone is contrary to the result of the previous study (Moon, 1987). On the basis of identification of the increase in the Al content of the limestone in the mineralized zone, it could be deduced that the decrease in the Si content of the Pungchon limestone might be due to the result of increase in the alteration products mainly occurred along fracture-system such as joint cracks or minor faults and that the phenomena shown by the Si and Al content in the mineralized zone might be derived from the thermal effect of granite extended mineralizing activity to the overlied limestone on the surface. Higher mean values of Fe and Al as well as lower mean values of carbon content and the ${\delta}^{13}C$ than mean values of those in the Pungchon limestone at the northern limb of the Hambaeg Syncline may be applicable in exploration for blind orebodies.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.269-276
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• 2004

The Indonesian Archipelago is located in the southern tip of the Eurasian plate. The diverse subduction system of the Indonesia region records interactions between three megaplates (Eurasian, Indian-Australian, and Pacific plates) and many smaller plates. The geology of Indonesian Archipelago is characterized by many factors such as subduction zone complexes, magmatic arc rocks associated with plate tectonics, the arc granite and volcanic rocks, and the related metamorphic rocks. The base-metal deposits of Indonesia have a great effect on petrochemical character of parent rocks and geotectonic environments. The base-metal deposits can be classified into four types as hosted by felsic-intermediate intrusive rocks, hosted by ultramafic rocks, hosted by volcanic rocks, and hosted by sedimentary rocks. The gold deposits are divided into three types: epithermal gold deposits, porphyry copper associated gold deposits, and alluvial gold deposits. Especially, Indonesian island uc, with its numerous plates tectonic, has an high potential for epithermal gold deposits. Indonesia with many old and present subduction zones and sub-aerial calcalkaline volcanic rocks is a very promising country for epithermal gold mineralization.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.765-779
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• 2023

The Daum Vent Field (DVF) was newly discovered in the Central Indian Ridge during the hydrothermal expedition by the Korea Institute of Ocean Science & Technology (KIOST) in 2021. In this paper, we describe the detailed mineralogy and geochemistry of hydrothermal chimney and mound to understand the nature of hydrothermal mineralization in the DVF. The mineral assemblages (pyrite±sphalerite±chalcopyrite) of dominant sulfides, FeS contents (mostly <20 mole %) of sphalerite, and (Cu+Zn)/Fe values (0.001-0.22) of bulk compositions indicate that the DVF has an strong affinity with basaltic-hosted seafloor massive sulfide (SMS) deposit along the oceanic ridge. Combined with the predominance of colloform and/or dendritic-textured pyrite and relatively Fe-poor sphalerite in chimneys, the fluid-temperature dependency of trace element systematics (Co, Mn, and Tl) between chimney and mound indicates that the formation of mound was controlled by relatively reducing and high-temperature fluids compared to chimney. The δ³⁴S values (+8.31 to +10.52‰) of pyrite reflect that sulfur and metals were mainly leached from the associated basement rocks (50.6-61.3%) with a contribution from reduced seawater sulfur (38.7-49.4%). This suggests that the fluid-rock interaction, with little effect of magmatic volatile influx, is an important metal source for the sulfide mineralization in the DVF.

• Economic and Environmental Geology
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• v.48 no.1
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• pp.1-13
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• 2015

The geology of the Seungryung Zn deposit, located in the Muzu basin, consists of Precambrian leucocratic granitic gneiss, Cretaceous clastic rocks, pyroclastic rocks, and intrusive rocks. The deposit shows a weakly skarnized hydrothermal replacement ore developed along limestone bed in the gneiss. The mineralization can be divided into three stages: the early skarnization producing garnet and pyroxene, the main mineralization in the middle stage precipitating most metallic minerals such as magnetite, sphalerite, chalcopyrite, pyrrhotite, Pb-Ag-Bi-S system minerals, and the late stage for altered or low temperature minerals such as chlorite and marcasite. Pb-Ag-Bi-S system minerals include heyrovskite-eskimoite solid solution, lillianite-gustavite solid solution, and vikingite. Chalcopyrite diseases are quite common in sphalerite showing bead chains and dusting textures. The ${\delta}^{34}S$ values of sulfides minerals are concentrated within the narrow range of 3.4~4.1‰ for pyrite, 3.3~4.3‰ for sphalerite, 4.0~4.3‰ for chalcopyrite, and 2.8‰ for galena, suggesting that most sulfur is of igneous origin. Sulfur isotope geothermometry is calculated to be $346{\sim}431^{\circ}C$, implying that the mineralization occurred at relatively high temperature. FeS contents of sphalerite are relatively high in the range of 6.58~20.16 mole% (avg. 16.58 mole%) with the enrichment of Mn compared to Cd, similarly to representative skarn Pb-Zn deposits in South Korea. On the contrary, sphalerite from Au-Ag deposits in the Seolcheon mineralized zone around the Seungryung deposit is enriched in Cd, showing similar feature like representative epithermal Au-Ag deposits. This suggests that around the related igneous rocks, magnetite and sphalerite were produced at high temperature in the Seungryung deposit, and with decreasing temperature and compositional change of mineralizing fluids, Au-Ag mineralization proceeded in the Seolcheon mineralized zone.

• Economic and Environmental Geology
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• v.39 no.5 s.180
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• pp.567-581
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• 2006

The Au-Ag lode deposits in South Korea are closely associated with the Mesozoic granitoids. Namely, the Jurassic deposits formed in mesozonal environments related to deep-seated granitoids, whereas the Cretaceous ones were developed in porphyry-related environments related to subvolcanic granitoids. The time-space relationships of the Au-Ag lode deposits in South Korea are closely related to the changing plate motions during the Mesozoic. Most of the Jurassic auriferous deposits (about $165{\sim}145$ Ma) show fluid characteristics typical of an orogenic-type gold deposits, and were probably generated in a compressional to transpressional regime caused by an orthogonal to oblique convergence of the Izanagi Plate into the East Asian continental margin. On the other hand, strike-slip faults and caldera-related fractures together with subvolcanic activity are associated with major strike-slip faults reactivated by a northward (oblique) to northwestward (orthogonal) convergence, and probably have played an important role in the formation of the Cretaceous Au-Ag lode deposits (about $110{\sim}45$ Ma) under a continental arc setting. The temporal and spatial distinctions between the two typical Mesozoic deposit styles in South Korea probably reflect a different thermal episodes (i.e., late orogenic and post-orogenic) and ore-forming fluids related to different depths of emplacement of magma due to regional changes in tectonic environment.

• Economic and Environmental Geology
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• v.12 no.2
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• pp.79-93
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• 1979

Twenty five samples of the scheelite-powellite series from twelve Korean tungsten deposits of various geologic settings were studied mineralogically and geochemically. Variations in the trace-element contents of the scheelite minerals are considered in relation to geologic settings and mineralogic properties. Scheelites from ore deposits developed in similar geologic settings and under similar physicochemical conditions are characterized by specific combinations of trace elements.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.110-110
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• 2012

아라미드 섬유소재는 고강도, 고내열성의 소재로 다양한 용도전개가 가능하나, 일광 및 부식에 의한 내광성 및 내후성이 급격하게 저하되는 단점이 있다. 자외선의 광화학적 작용에 의해 변퇴, 경화, 취하, 강도저하가 일어나는 단점을 보완하기 위해 내광성 및 내화학성이 우수한 전이금속산화물 소재와의 복합화를 통해 내광성 및 내화학성 개선에 대하여 연구하였다. zinc acetate 수화물과 수산화리튬을 무수에탄올로 용해시킨 용액을 강하게 교반하여 나노 산화아연 졸을 제조하였다. 제조된 나노크기의 zinc oxide 입자의 형상과 입자분포 등 제조특성을 입도분석기, FE-SEM 및 EDS 분석을 통하여 고찰하였으며, 제조된 나노졸을 아라미드 섬유에 침지시켜 Xenon-arc 내후성시험기에서 80시간 동안 노출시켜 노출시간에 따른 물성변화를 분석하였다. 나노졸을 5~20% 픽업으로 패딩한 후 광에 노출된 아라미드의 인장강도는 나노졸을 처리하지 않은 아라미드 섬유보다 20~30% 개선된 인장강도를 나타내었다.

• Economic and Environmental Geology
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• v.44 no.4
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• pp.313-320
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• 2011

The Taebaegsan Mineralized District is the most prospective region for the useful mineral commodities such as a coal, non-metallic, metallic mineral in South Korea. From a general point of view, Cambro- Ordovician limestone formations, Myobong slate and Pungchon (Daegi) limestone, are the most fertilizable formations in the Taebaegsan Mineralized District. The geology around Weondong mine area consists mainly of Carboniferous-Triassic formations and Cambro-Ordovician formations intruded by rhyolite/quartz porphyry. The great overthrusted fault of N40~$50^{\circ}E$ direction, so called Weondong overthrust fault, is observed in the central part of the mine area and the NS fault system cuts the overthrusted fault. By postulating from the favorable geological and structural condition around Weondong area, the possibility of deep seated hidden ore bodies is expected. In 2010, on the basis of the results of LOTEM and CSAMT survey, the cross-hole survey was performed for the investigation of the hidden polymetallic ore body in the deep parts of the Weondong mine area and the grade of the newly-discovered orebody is as follows; (1) The cut-off grade for lead-zinc 3%; an weighted average grade 5.50% (2.7 m), (2) The cutoff grade for copper 0.1%; an weighted average grade 0.91% (14.65 m), (3) The cut-off grade for iron 30%; an weighted average grade 38.18% (3.3 m), (4) $WO_3$ for each cut-off grade(0.01%, 0.05%, 0.1%); an weighted average grade 0.29 wt. % (8.8 m), 1.15 wt. % (2.1 m), 1.97 wt. % (1.2 m), (5) $MoS_2$ for each cut-off grade(0.01%, 0.1%); an weighted average grade 0.15 wt. % (6.3S m), 0.28 wt. % (3.15 m), (6) $Ta_2O_5$ for each cut-off grade (0.01%, 0.1%); an weighted average grade 0.13% (19.S m), 1.11% (1.8 m), (7) $Nb_2O_5$ for each cut-offgrade (0.01%, 0.1%); an weighted average grade 0.06% 11.5 m), 0.15% (3.0 m).

• Economic and Environmental Geology
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• v.17 no.2
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• pp.115-139
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• 1984

The Cu-Pb-Zn-Ag hydrothermal vein-type deposits which comprise the Sambong mine occur within calc-alkaline volcanics of the Cretaceous Gyeongsang Basin. The ore mineralization took place through three distinct stages of quartz (I and II stages) and calcite veins (III stage) which fill the pre-existing fault breccia zones. These stages were separated in time by tectonic fracturing and brecciation events. The reflection variations of one mineral depending on mineralization sequence are considered to be resulted from variation in its chemical composition due to different physico-chemical conditions in the hydrothermal system. The reflection power of sphalerite increases with the content of Fe substituted for Zn. Reflectances of the sphalerite grain are lower on (111) than on (100) surface. The spectral profiles depend on the internal reflection color. Sphalerite, showing green, yellow and reddish brown internal reflection, have the highest reflection power at $544m{\mu}$ (green), $593m{\mu}$ (yellow) and $615m{\mu}$ (red) wavelength, respectively. Chalcopyrite is recognized as biaxial negative from the reflectivity data of randomly oriented grains measured at the most sensitivity at $544m{\mu}$. The microindentation hardness against the Fe content (wt. %) for the sphalerite increases to 8.05% Fe and then decreases toward 9.5% Fe content. Vickers hardness of the sphalerite is considerably higher on surface of (100) than on (111). The relationship between Vickers hardness and crystal orientation of the galena was determined to be $VHN_{(111)}$ > $VHN_{(210)}$ > $VHN_{(100)}$. The softer sulfides have the wider variation of the diagonal length in the indentation. Diagonal length in the indentation is pyrite

• Economic and Environmental Geology
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• v.34 no.6
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• pp.507-522
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• 2001

At the Tongyeong mine, quartz, rhodochrosite (kutnahorite), muscovite, illite, pyrite, galena, chalcopyrite. sphalerite, acanthite, and hessite are the principal vein minerals. They were deposited under epithermal conditions in two stages. Ore mineral assemblages and associated gangue phases in stage can be clearly divided into two general associations: an early cycle (band) that appeared with introduction of most of the sulfides and electrum, and a later cycle in which base metal and carbonate-bearing assemblages (mostly rhodochrosite) became dominant. Tellurides and some electrum occur as small rounded grains within subhedral-to euhedral pyrite or anhedral galena in stageII. Sulfide mineralization is zoned from pyrite to galena and sphalerite. We have used computer modeling to simulate formation of four stages of vein genesis. The reaction of a single fluid with andesite host rock at 28$0^{\circ}C$, isobaric cooling of a single fluid from 26$0^{\circ}C$ to 12$0^{\circ}C$, and boiling and mixing of a fluid with both decreasing pressure and temperature were studied using the CHILLER program. Calculations show that the precipitation of alteration minerals is due to fluid-andesite interaction as temperature drops. Speciation calculations confirm that the hydrothermal fluids with moderately high salinities and pH 5.7 (acid), were capable of transporting significant quantities of base metals. The abundance of gold in fluid depends critically on the ratio of total base metals and iron to sulfide in the aqueous phase because gold is transported as an Au(HS)$_2$- complex, which is sensitive to sulfide activity. Modeling results for Tongyeong mineralization show strong influence of shallow hydrogenic processes such as boiling and fluid mixing. The variable handing in stageII mineralization is best explained by maltiple boilings of hydrothermal fluid followed by lateral mixing of the fluid with overlying diluted, steam-heated ground water. The degree of similarity of calculated mineral assemblages and observed electrum composition and field relationships shows the utility of the numerical simulation method in identifying chemical processes that accompany boiling and mixing in Te-bearing Au-Ag system. This has been applied in models to narrow the search area for epithermal ores.