• Journal of the Mineralogical Society of Korea
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• v.8 no.2
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• pp.73-85
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• 1995

춘천 지역 구봉산층군 내에서 산출되는 백색 및 흑회색 투감섬석에 대하여 전자현미분석과 리트벨트법에 의하여 결정화학적 특징이 연구되었다. 화학 조성상 백색 투감섬석 (WHT)은 흑회색형 (BLT)에 비하여 Al과 Na의 양은 많고, Mg와 Ca의 양은 적은 차이를 보여준다. 단위포의 크기에 있어 b축의 길이는 WHT가 BLT보다 약 0.013$\AA$ 크다. 이는 후자의 M(4) 자리에 보다 많은 Na와 Mg가 치환된 결과로서 계사된 $\AA$로 잘 일치하고 있다. 자리 점유율에 있어 BLT의 경우 모든 Al이 T(2)에 채워지며, WHT에서는 T(1), T(2)에 각각 0.138, 0.181씩 Si를 치환하고 있다. M(1), M(2), 및 M(3)는 모두 Mg에 의해 채워지고 있으며, Ca가 채워지는 M(4)에는 BLT에서는 소량의 Mg가 들어 있다. (001) 방향으로 투각섬석의 구조를 작도해 보면, WHT에서는 사면체의 바닥면이 T(1) 안쪽으로 다소 기울어져 있으나, BLT에서는 T(1)과 T(2)가 서로 마주보며 기울어져 있는 특이한 양상을 보여준다. 이러한 구조상의 차이점은 앞으로 보다 많은 투각섬석에 대한 구조적인 연구를 수행할 필요가 있음을 보여준다.

• Economic and Environmental Geology
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• v.25 no.4
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• pp.463-477
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• 1992

The study area consists of sedimentary and volcanic rocks of Gyeongsang Supergroup, granitoid intrusives, and hornfelses around the granitoids. Granitoid intrusives occur in small stocks in Nijeon-ri, Uggogri, and Yul-ri area. The masses in Nijeon-ri and Uggog-ri are hornblende-biotite granodiorite, biotite granodiorite respectively, and Yul-ri mass is biotite granite. Surrounding sediments of these masses were thermally metamorphosed and contact aureoles were formed. The studied granitoids are considered to be formed by sequential crystallization-differentiation from calc-alkalic granitoid magma. Metamorphic minerals occurring in contact aureole are chlorite, actinolite, epidote, and biotite. Diopside and hornblende are observed in small amount in some lithology around contact aureole. The lithology of contact aureole is predominantly silty and sandy, and characteristic metamorphic minerals were poorly developed because of low temperature metamorphism. Low temperature in contact aureole could be deduced from the facts that the intrusions were small size, shallow depth, low temperature, and rare movement of volatiles from magma.

• Water for future
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• v.14 no.4
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• pp.73-81
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• 1981

More than 650 numbers of water well ranging in depth from 100M to 200M were installed in South Korean Penninsula during the last decade for the purpose of industrial use and municipal water supply. Those data were compiled and synthesized by writer to determine their hydrogeologic occurences in accordance with their geologic and areal characteristics. Rocks yielding the deep seated ground water beared in the geologic primary and secondary porosities are classified into 6 groups according to their geologic, hydrogeologic, and topographic characteristics, that are: volcanic, sedimentary, meta-sediment and/or schist, andesitic, gneissic, and granitic rocks. The order of ground water productivity of the groups is as written above. Even granitic rocks including porphyries, granite, and intermediate and basic plutonic rocks is considered to be the most poorest ground water yielding group among 6, it's average yield form a single well with average drilling depth of 116M is about 225 cubic meters per day if it's drilling site is properly located. Generally speaking, seizable geologic structures such as fractured, sheared, and faulted zone at the flat surface and valley center yield almost 310% more of deep seated bet rock ground water in comparision with minor structures of joints, bedding planes, and so on that are occured at high land. 50 numbers of water well drilled at crystalline rocks were specially checked and measured it's ground water yie 1ds at each drilled depth to determine each interval's productivity while hammer drilling was going on. The results indicate that the specific capacity and yield of each water well at a depth below 70M to 80M was almost neglegible. It means that optimum well depth of crystalline rocks, except the area having seizable geologic structures, shall be not deeper than 80M.

• Economic and Environmental Geology
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• v.44 no.4
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• pp.273-288
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• 2011

Chon-Ashuu copper mining claim area is located, in terms of the geotectonic setting, in the northern part of the suture line which is bounded with the marginal part of Issik-kul micro-continent on the southern part of North Tien-Shan terrane. The geological blocks of Chon-Ashuu districts belong to the southern tip of Kazakhstan orocline. The rock formation of this area are composed of the continental crust or/and arc collage and the paleo-continental fragments-accretionary wedge complex of pre-Altaid orogenic materials. ASI(Alumina Saturation Index) of Paleozoic plutonic rocks in Chon-Ashuu area belong to the peraluminous and metaluminous rocks which were generated from fractional crystallization of Island and volcanic arc crusts in syn-post collisional plate. The geology of the ChonAshuu area consists of upper Proterozoic and Paleozoic rock formations. According to Harker variation diagrams for Chon-Ashuu arenaceous sedimentary rocks, the silty sandstone of Chon-Ashuu area showing the mineralogical immaturity were derived from Island arc or the marginal environments of active continent in Cambro-Carboniferous period. Numerous intrusive rocks of Chon-Ashuu area are distributed along north east trending tectonic structures and are bounded on four sides by the conjugate pattern. The most common type of the plutonic rocks are granodiorite and monzodiorite. According to the molecular normative An-Ab-Or composition (Barker, 1979), the plutonic rocks in Chon-Ashuu area are classified into tonalite - trondhjemite - granodiorite (TTG) series which are an aggregation of rocks which is the country rock of copper mineralization, that are formed by melting of hydrous mafic crust at high pressure.

• Economic and Environmental Geology
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• v.37 no.5
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• pp.555-568
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• 2004

The demand of aggregate resources in Korea has been increased with a rapid economic growth since the 1980s. About 25% of the total aggregate production is derived from riverine aggregates, 20% to 25% from marine sands, 40% to 45% from crushed aggregate and the rest 5% to 15% from old fluvial deposits. The abundance of crushed coarse aggregates varies in the uniform distribution of country, but in general it can be concentrated in the most densely populated areas, five main cities. Typical rock types of the Korean crushed stones are classified as plutonic rocks of 27%, metamorphic rocks of 32%, sedimentary rocks and volcanic rocks of 18%, respectively. The most abundant coarse aggregate used in the country is obtained from granite (25% of total) and subordinately gneiss (20%), sandstone (10%) and andesite (10%). Although rock types using as dimension stone are only fifteen, those as aggregate amount up to twenty nine rocks. These rocks consist of plutonic rocks such as granite, syenite, diorite, aplite, porphyry, felsite. dike and volcanic rocks such as rhyolite, andesite, trachyte, basalt, tuff, volcanic breccia and metamorphic rocks such as gneiss, schist, phyllite, slate, meld-sandstone, quartzite, hornfels, calc-silicate rock, amphibolite. And sandstone, shale, mudstone, conglomerate, limestone, breccia, chert are main aggregate sources in tile sedimentary rocks. The abundance of plutonic rocks is the highest in Chungcheongbuk-do, and decreases as the order of Jeollabuk-do, Gangwon-do and Gyeonggi-do. In Jeollanam-do, volcanic aggregates occupy above 50%, on the contrary sedimentary aggregates are above 50% in Gyeongsangnam-do.

• Journal of the Mineralogical Society of Korea
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• v.17 no.4
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• pp.339-355
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• 2004

Locality of domestic high-Ca limestones can be divided into three districts, i.e., (1) the Jecheon-Danyang area, (2) the Samcheok-Taebaek-Jungsun area, and (3) the Uljin-Andong area, in accordance with their geologic background and type of the deposits. Except for some crystalline limestones from the Jecheon-Danyang area, domestic high-Ca limestones were mostly recrystallized and Ca-enriched by the effects of hydrothermal alteration and/or thermal metamorphism. The lime-stones can be also divided into crystalline limestone type, marble type, micro- and mega-crystalline calcite types on the basis of their composition, crystallinity, and mineral facies. An applied-mineralogical characterization of the high-Ca limestones was done through the systematic analyses and tests for the limestones. The high-Ca limestones from the area (1), which are megascopic ally close to the original limestone in lithology, display lower whiteness, higher contents of CaO (51 ～ 54 wt.%), low crystallinity, and fine-grained texture. Two typical hydrothermal types of the high-Ca limestones from the area (2), i.e., micro- (mostly 0.2～0.3 mm) and mega-crystalline (2～15 em) calcite types, have comparatively higher whiteness and rather variable CaO contents (50～55 wt.%) with exhibiting quite different crystallinity each other. The micro-crystalline calcite type is especially dominant in this area, and has comparatively uniform crystallinity and homogeneous composition. Compared to these limestones, the high-Ca limestones from the area (3) show remarkable differences in grade and quality according to their types of deposit and occurrence. Based on these mineral characters and chemical composition, a possible scheme for industrial uses of the domestic high-Ca limestones was suggested.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.167-175
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• 2009

The geology of Sepola district in Mali is consisted of Birrimian group with metasedimentary rocks of lower Proterozoic and volcanoclastics, and later intrusive igneous rocks. Ore diposit in this district has the characteristics of vein- and disseminated-type gold deposit which was formed by infilling the secondary fracture zones related to the large-scale fault zone of NW direction within Birrimian group. It is confirmed as promising that Barani district has the gold grade of 0.53${\sim}$9.21 g/t with the extension of 1.3 km and width of 1 to 20.1 m. The ore mineralogy is simple with electrum, pyrite and galena. Fineness of gold grain ranges from 848 to 915(average 891) indicating mesothermal to hypothermal environment. Fluid inclusions are classified as liquid-rich type I. gas-rich type II and liquid-$CO_2$ bearing type III. Primary and pseudosecondary inclusions homogenize from 236 to 393$^{\circ}C$ with salinity of 0.0 to 8.6 wt% NaCl. Secondary inclusions homogenize from 103 to 184$^{\circ}C$ with salinity of 0.7 to 8.6 wt.%. From the relationship between homogeniztion temperature and salinity, it may be thought that auriferous fluid experienced dilution and cooling through inflow of meteoric water after fluid unmixing derived from pressure decrease in the temperature range of 400 to 250$^{\circ}C$. From the massive occurrence of quartz vein, simple mineralogy with paucity of sulfide, and presence of liquid-$CO_2$ bearing with high homogenization temperature, it is thought that gold mineralization in Sepola district correspods to the mesothermal to hypothermal ore deposit.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.2
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• pp.107-120
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• 2021

The Komdok Pb-Zn deposit, which is the largest Pb-Zn deposit in Korea, is located at the Hyesan-Riwon metallogenic zone in Jiao Liao Ji belt included Paleoproterozoic Macheolryeong group. The geology of this deposit consists of Paleoproterozoic metasedimentary rocks, Jurassic Mantapsan intrusive rocks and Cenozoic basalt. The Komdok deposit which is a SEDEX type deposit occurs as layer ore and vein ore in the Paleoproterozoic metasedimentary rocks. Based on mineral petrography and paragenesis, dolomites from this deposit are classified four types (1. dolomite (D₀) as hostrock, 2. early dolomite (D₁) associated with tremolite, actinolite, diopside, sphalerite and galena from amphibolite facies, 3. late dolomite (D₂) associated with talc, calcite, quartz, sphalerite and galena from amphibolite facies, 4. dolomite (D₃) associated with white mica, chlorite, sphalerite and galena from quartz vein). The structural formulars of dolomites are determined to be Ca_1.00-1.20Mg_0.80-0.99Fe_0.00-0.01Zn_0.00-0.02(CO₃)₂(D₀), Ca_1.00-1.02M_0.97-0.99Fe_0.00-0.01Zn_0.00-0.02(CO₃)₂(D₁), Ca_0.99-1.03Mg_0.93-0.98Fe_0.01-0.05Mn_0.00-0.01As_0.00-0.01(CO₃)₂(D₂) and Ca_0.95-1.04Mg_0.59-0.68Fe_0.30-0.36Mn_0.00-0.01 (CO₃)₂(D₃), respectively. It means that dolomites from Komdok deposit have higher content of trace elements (FeO, MnO, HfO₂, ZnO, PbO, Sb₂O₅ and As₂O₅) compared to the theoretical composition of dolomite. These trace elements (FeO, MnO, ZnO, Sb₂O₅ and As₂O₅) show increase and decrease trend according to paragenetic sequence, but HfO₂ and PbO elements no show increase and decrease trend according to paragenetic sequence. Dolomites correspond to Ferroan dolomite (D₀, D₁ and D₂), and Ferroan dolomite and ankerite (D₃), respectively. Therefore, 1) dolomite (D₀) as hostrock was formed by subsequent diagenesis after sedimentation of Paleoproterozoic (2012~1700 Ma) silica-bearing dolomite in the marine evaporative environment. 2) Early dolomite (D₁) was formed by hydrothermal metasomatism origined metamorphism (amphibolite facies) associated with intrusion (1890~1680 Ma) of Paleoproterozoic Riwon complex. 3) Late dolomte (D₂) was formed from residual fluid by a decrease of temperature and pressure. and dolomite (D₃) in quartz vein was formed by intrusion (213~181 Ma) of Jurassic Mantapsan intrusive rocks.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.2
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• pp.115-127
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• 2020

The Unsang gold deposit has been one of the three largest deposits (Daeyudong and Kwangyang) in Korea. The deposit consists of Au-bearing quartz veins filling fractures along fault zones in Precambrian metasedimentary rock and Jurassic Porphyritic granite, which suggests that it might be an orogenic-type. Based on its mineral assemblages and quartz textures, quartz veins are classified into 1)galena-quartz, 2)pyrrhotite-quartz, 3)pyrite-quartz, 4)pegmatic quartz, 5)muscovite-quartz, and 6)simple quartz vein types. The pyrite-quartz vein type we studied shows the following alteration features: sericitization, chloritization, and silicification. The quartz vein contains minerals including white quartz, white mica, chlorite, pyrite, rutile, calcite, monazite, zircon, and apatite. Rutile with euhedral or medium aggregate occur at mafic part from laminated quartz vein. Two types of rutile are distinguishable in BSE image, light rutile is texturally later than dark rutile. Chemical composition of rutile has 89.69~98.71 wt.% (TiO₂), 0.25~7.04 wt.% (WO₃), 0.30~2.56 wt.% (FeO), 0.00~1.71 wt.% (Nb₂O₅), 0.17~0.35 wt.% (HfO₂), 0.00~0.30 wt.% (V₂O₃), 0.00~0.35 wt.% (Cr₂O₃) and 0.04~0.25 wt.% (Al₂O₃), and light rutile are higher WO₃, Nb₂O₅ and FeO compared to the dark rutile. It indicates that dark rutile and light rutile were formed at different stage. The substitution mechanisms of dark rutile and light rutile are suggested as followed : dark rutile [(V³⁺, Cr³⁺) + (Nb⁵⁺, Sb⁵⁺) ↔ 2Ti⁴⁺, 4Cr³⁺ (or 2W⁶⁺) ↔ 3Ti⁴⁺ (W⁶⁺ ↔ 2Cr³⁺), V⁴⁺ ↔ Ti⁴⁺], light rutile [2Fe³⁺ + W⁶⁺ ↔ 3Ti⁴⁺, 3Fe²⁺ + W⁶⁺ ↔ Ti⁴⁺ + (V³⁺, Al³⁺, Cr³⁺) +Nb⁵⁺], respectively. While the dark rutile was formed by cations including V³⁺, V⁴⁺, Cr³⁺, Nb⁵⁺, Sb⁵⁺ and W⁶⁺ by regional metamorphism of hostrock, the postdating light rutile was formed by redistribution of cations from predating dark rutile and addition of Fe²⁺ and W⁶⁺ from Au-bearing hydrothermal fluid during ductile shear.

• The Journal of the Petrological Society of Korea
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• v.5 no.1
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• pp.35-51
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• 1996

The granitic rocks in the vicinity of the Mt. Sorak, the northeastern part of the NE-SW elongated Mesozoic granitic batholith in the Kyeonggi massif, consist of granodiorite, biotite granite, two-mica granite and alkali feldspar granite. Variations In major and most trace elemental abundances show a typical differentiation trend in a granitic magma. Granitic rocks all display a calc-alkaline trend in the AFM diagram. Also, In the ACF diagram discriminating between I- and S-type granitic rocks, granodiorite and most biotite granite in the southeastern area represent I-type and magnetite-series characteristics, while most biotire granite and two-mica granite in the northwestern area exhibit S-type and ilmenite-series ones.According to recent studies of the granitle rocks In the Inje-Hongcheon district. all ihe granitic rocks distributed in the northeastern part of the Kyeonggi massif have been classified as late Triassic to early Jurassic Daebo granite. With reference of the formerly published ages, an age oi $125.6{\pm}4.4$ Ma calculated by the slope in the plot of $^{87}Rb/^{86}Sr-^{87}Sr/^{86}Sr$ for the biotite granite samples from the southeastern area is inferred as an emplacement age for the granitic rocks in the vicinity of the Mt. Sorak. On the basis of elemental variations and Sr isotope compositions, an possible evolutional process for the granitic magmas in this area is suggested. The primary magma of I-type and magnetite-series generated about 125 Ma by partial melting of igneous originated crustal materials, might be emplaced and evolved through fractional crystallization, convection and assimilation of the surrounding Precambrian metasediments to become S-type and ilmenlte-serles in the outer area, and then solidified to granodiorite, biotite granite and two-mica granite.At the latest stage, the evolved hydrothermal solution altered the formerly solidified biotite granite to alkali feldspar granite and probably later local igneous activities affected the alkali feldspar granite again.