• Economic and Environmental Geology
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• v.20 no.1
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• pp.61-75
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• 1987

The Daejang mine is one of the representatives of Cu-Pb-Zn-(Ag) vein deposit related genetically to late Cretaceous granitoid in Korea. Sericite from an alteration halo of the mine yielded a K-Ar date of $95{\pm}3.5Ma$. Based on macrostructures of vein filling, three major mineralization stages (I, II and III) are distinguished by tectonic breaks. Major ore constituents are arsenopyrite, pyrite, pyrrhotite, sphalerite, chalcopyrite, galena, boulangerite, with small amounts of Ag-bearing tetrahedrite, pyrargyrite, native bismuth, marcasite, siderite, ankerite, gudmundite and calcite. Characteristic feature of each mineralization stage and compositional variation of sphalerite and arsenopyrite are discussed in relation to the genetic environments. The FeS contents of sphalerites are 20.5~14.9 mole % in stage I, 17.9~11.9 mole % in stage IIA, 17.0~9.2 mole % in stage IIB, and 6.9~4.7 mole % in stage III. Their results are indicative of decreasing FeS contents during mineralization process in sphalerite coexisting with sulfur-rich sulfide assemblages, such as monoclinic pyrrhotite and pyrite, and is agreement with the conclusions shown by Scott and Kissin(1973). The composition of arsenopyrite decrease also in As content from stage I to stage III, and the compositional variation correlate with position of the associated minerals in the paragenesis. Temperature and pressure of the mineralization are determined as $250{\sim}430^{\circ}C$ and 4.0~0.3kb respectively, based on the chemistry of the minerals.

• The Journal of the Petrological Society of Korea
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• v.3 no.3
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• pp.220-233
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• 1994

The granitic rocks in the Poeun - Sogrisan area are composed of the Jurassic Poeun granodiorite and the Cretaceous Sogrisan granites. The latter can be divided into three rock types : coarse-grained biotite granite, porphritic biotite granite and granite porphyry. Petrographical observations, especially focusing on the quartz-feldspar intergrowth texture, suggest that the Sogrisan granites has emplaced at shallower level and crystallized more rapidly than the Poeun granodiorite. The F, Cl contents and the Fe/(Fe+Mg) ratio of biotite and muscovite in the Sogrisan granites are higher than those in the Poeun granodiorite. The anor-thite contents of plagioclase in the Poeun granodiorite are higher then in the Sogrisan granites. Ilmenite in the Sogrisan granites is more enriched in Mn and depleted in Fe than that in the Poeun granodiorite. The whole-rock magnetic susceptibility values (in $10^{-6}$ emu/g unit) are higher in the Sogrisan granites (33~144) than the Poeun granodiorite (9~12), indicating that the former generally belongs to magnetite-series granitoid and the latter to ilmenite-series one. The Sogrisan granites has solidified under more oxidizing environment than the Poeun gra-nodiorite, judging from the whole-rock magnetic susceptibility measurements as well as the chemical compositions of biotite and ilmenite.

• Economic and Environmental Geology
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• v.30 no.4
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• pp.379-393
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• 1997

Geology of the Zbezkazgan copper deposit in Kazhkstan is mainly composed of Permian and Carboniferous sedimenary rocks in which copper minerals are mainly contained in grey sandstone of Carboniferous age. There are 28 layers of copper ore bodies in Zbezkazgan suite. Thickness of the ore bodies ranges from one to 35 meters, grade of the crude ore ranges from 2 to 5 wt % Cu and the extension of the orebodies is 5 to 7 km. Microscopic study on specimens from the Zbezkazgan ore deposit has exposed clues to understand the origin of this deposit. Alternatively deposited grey sandstone and red sandstone are mainly composed of quartz and feldspar grains. A big difference between the grey sandstone and the red sandstone is in grain size, the former is larger than the latter. Chalcocites as main copper minerals have cemented through grain boundary. It is assumed that quartz, feldspar and copper were derived from granitoid in which copper mineralization had taken place before exposing to weathering. The chalcocites were precipitated by a sudden change of geochemical condition (Eh, pH, temperature, etc.) of fluid which had carried quartz, feldspars, copper ions and sulphate during formation of grey sandstones. The copper ions and sulphate were stable in fluid during sedimentation of oxidation environment, however, the copper ions were no more stable at the reduced environment and changed to stable forms to precipitate copper minerals by reaction of copper ions and hydrogen sulfides. This chemical precipitation of copper minerals in the sandstone attributes to the assumption of hydrothermal origin on this sedimentary origined deposit.

• Economic and Environmental Geology
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• v.28 no.5
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• pp.445-454
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• 1995

The petrochemical data of the porphyritic granites of Cretaceous age in the Yonghwa-Seolcheon area show the trend of subalkaline magma, calc-alkaline magma, I-type granitoid and magnetite series. This granite is the relevant igneous rock of gold-silver mineralization in this mining district Fluid inclusions have been studied in phenocryst quartz from the Cretaceous porphyritic granite. Three main types of fluid inclusion were found : liquid-rich inclusion(I type), gas-rich inclusion(II type) and solid-bearing inclusions(III-A, III-B). The solid-bearing inclusions(III-A,B) represent the earliest trapped fluids. They have salinities between 41.0 and 67.5 wt% equivalent to NaCl. These are high saline inclusions containing NaCl and KCl daughter crystals. Homogenization temperature inferred from the fluid inclusion study ranges from 650 to $75^{\circ}C$ Type I and II inclusions were observed within the same fracture. This cause for these differences in degree of filling is evidence of boiling. Salinities of type I and II inclusions range from 9.87 wt% to 15.29 wt%, from 8.40 wt% to 14.64 wt% NaCl equivalent, respectively.

• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.53-64
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• 2011

Grus weathering mantles are widely distributed in Southern Korean Peninsula and are considered to be results of chemical weathering related to palaeoclimate milieu. This paper attempts to address this issue by CIA(chemical index of alteration). The climatic approach to the formation of grus mantles offers limited explanation of field occurrences, as these materials are widespread across climatic zones, from the humid tropics to cool temperate areas, although rates of grusification are likely to be influenced by climatic parameters. CIA values for granitoid weathering mantles in S. Korea are 50, which is the same of unweathered granitic rocks. Grus mantles in Korean peninsula show very low level in chemical alteration by CIA.

• 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.27 no.3
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• pp.237-246
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• 1994

Tin mineralizations in South Korea have been found only in the Ulchin and Sangdong areas. They appear to be in close spatial association with the Wangpiri granitoid in the UlChin area, and the Nonggeori and Naedeogri granites in the Sangdong area. However, previous works have revealed that there are considerable differences in geological setting, mineralogical and geochemical compositions among these granitoids concerned. The roles of discriminant and multiple regression analysis have been examed to establish geochemical differences among the tin-granitoids and to identify elements relating to tin mineralizations. The data set used in this study consists of 60 observations with 29 elements which are cited from pre-existing publications. A stepwise discriminant analysis determined the group of variables that differentiate between samples from four training sets; Buncheon, Wangpiri, Nonggeori and Naedeogri granitoids. These granitoids were most effectively discriminated on the basis of major elements FeO, CaO and $P_2O_5$ and also by the trace elements Rb and Zr. Results of the multiple regression analysis shows that the level of Sn in granitoids depends positively on ones of MnO, Rb and FeO and negatively $P_2O_5$. Graphical representation of discriminant scores on sampling locations greatly aid recognition of differences in the geochemical characteristics in terms of spatial distribution of granitoids examed. The application of the discriminant analysis provides a potential means of identifying and comparing geochemical characteristics.

• Economic and Environmental Geology
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• v.28 no.3
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• pp.287-303
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• 1995

Tungsten ore deposits in China show clearly their relationship between granitoids and orebodies. All kinds of different tungsten ore deposits, having the largest ore reserves in the world, occur in China. Major tungsten deposits in 1950'years were locally confined in three provinces such as Jiangxi, Hunan and Guangdong. However, the major tungsten ore deposits are replaced by new tungsten deposits such as Sandahozhuang, Xingluokeng, Shizhuan and Daminghsan deposit which may be larger than the previous major deposits. Tungsten ore deposits of China exhibit obviously the granitoid was the ore-bringer to form tungsten ore deposits. The wolframite-bearing quarz veins in China indicate that tungsten mineralization took place by crystallization of wolframite preferentially unless $Ca^{{+}{+}}$ was introduced from outside into the magma-origin-fluid, since it is understood that the scheelite in the Sangdong ore deposit was preferentially precipitated, because of chemical affinity, from the tungsten fluid in which Fe and Ca ions were as sufficient as to form magnetite, wolframite and scheelite. Tungsten deposits in the world are divided into two systems; W-Mo-Sn system and W-Mo system. Most of tungsten deposits in China dated to about 196-116 Ma belong to the W-Mo-Sn system, while late Cretaceous tungsten deposits such as the Sangdong deposit in Korea belongs to the W-Mo system. The genetic order of tin-tungsten-molybdenum mineralization observed in the Moping tungsten mine in China and the Sangdong in Korea may be attributed to volatile pressures in the same magma chamber. It is assumed from ages of tungsten mineralizations that ore elements such as tin, tungsten and molybdenum might be generated periodically by nuclear fission and fusion in a part of the mantle and the element generated was introduced into the magma chamber. The periodical generation of elements had determined association, depletion and enrichment of tin and molybdenum in tungsten mineralization and it results in little association of cassiterite in tungsten deposit of late Cretaceous ages. Different mechanism of emplacement of the ore-bearing magma has brought various genetic types of tungsten deposits as shown in China and the world.

• Journal of the Korean earth science society
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• v.22 no.3
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• pp.163-178
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• 2001

Granite gneiss, pophyroblastic gneiss and leucocratic gneiss are widely distributed in the Seungju-Suncheon area, the southwestern part of the Sobacksan Massif, Korea. These orthogneisses show intrusive relationships in outcrops of the study area. This study focuses on the geochemical properties and the tectonic environments for the original rocks of these orthogneisses. The pophyroblastic gneiss is plotted in diorite and granodiorite domain, and granite gneiss and leucocratic gneiss are plotted in both of granodiorite and granite domains on lUGS silica-alkali diagram. Geochemical properies of major elements suggest that these rocks are sub-alkali rock series, and were formed from S-type magma which generated in syn-collision tectonic environment. Discrimination diagrams using HFS elements suggest that original rocks of the three orthogneisses were granitoid of calc-alkali rock series, and were formed in syn-collision environment.

• Economic and Environmental Geology
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• v.27 no.4
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• pp.335-343
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• 1994

The Eonyang amethyst deposits are composed of vug quartz emplaced in the Eonyang granites of Mesozoic Cretaceous age. The Eonyang granites are composed of biotite granite, porphyritic biotite granite, aplite and miarolitic granite. The petrochemical data of the Eonyang granites show the trend of subalkaline magma, calc-alkaline magma, I-type granitoid and magnetite series. The vug quartz show the characteristic growth zoning (white quartz-smoky quartz-amethyst) from wall side. Generally fluid inclusions in the vug quartz can be divided into four main types based on compositions (I-type: gas inclusion, II-type: liquid inclusion, III-type: polyphase inclusion, IV-type: liquid $CO_2$-bearing inclusion). Solid phase of polyphase inclusions are halite(NaCl), sylvite(KCl), hematite ($Fe_2O_3$) and unknown anisotropic solid. Homogenization temperatures inferred from the fluid inclusion study ranges from $440^{\circ}C$ to $485^{\circ}C$ in white quartz, from $227^{\circ}C$ to $384^{\circ}C$ in smoky quartz, from $133^{\circ}C$ to $186^{\circ}C$ in amethyst, respectively. Salinities of fluid inclusions in each mineralization stages ranges from 40 wt.% to 58 wt.% in white and smoky quartz, from 1.0 wt.% to 8.7 wt.% in amethyst respectively. A consideration of the pressure regime during vug quartz deposition based on the boiling evidence suggests lithostatic pressure of less than 72 bars. This range of pressure indicate that vug quartz lay at depth of 750 m below the surface at the during mineralization.