• The Journal of Engineering Geology
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• v.20 no.1
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• pp.71-78
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• 2010

The Gagok mine is a contact metasomatic deposit, located at Gagok-myeon, Samcheok city and Cheoram-dong, Taebaek city, Gangwon province. The deposit lies within the limestone of Myobong and Pungchon formations, and exists the contact of intrusive granite porphyry. In order to determine the direction and extension of mineralization in the gallery and around the entrance of the ore deposit, we used the ground magnetic survey, the direct current (dc) resistivity survey using dipole-dipole array, and resistivity tomography survey. The ground magnetic survey did not detect the anomalous zone due to ore deposit, while the dc resistivity survey and resistivity tomography survey were successful in delineating the anomalous zone related to the extension of fault toward $N50^{\circ}W$.

• Economic and Environmental Geology
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• v.25 no.3
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• pp.283-296
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• 1992

The Keumryeong deposits is a low grade copper deposits in which copper minerals form disseminated grains and thin veinlets in felsic volcanics seem to be dacite. Alteration of the volcanics consists mainly pervasive propylitization and silicification. Potassic alteration characterized by biotite developed locally adjacent to southwestern contact of granodiorite body. Principal sulfide minerals in altered zone are mainly pyrite and lesser chalcopyrite. Chalcopyrite content in potassic zone is relatively higher than that of surrounding propylitized zone. Pyrite and chalcopyrite accompanies magnetite, molybdenite, sphalerite, pyrrhotite, arsenopyrite, pentlandite, marcasite, hematite, ilmenite, rutile, bismuthinite and native Bi as disseminations, veinlets and knots. Granodiorite body is propylitized and contains veinlets of pyrite, chalcopyrite and molybdenite. Fluid inclusions in sulfide-bearing quartz veinlets and quartz grains of felsic volcanics and granodiorite in altered zone consist of liquid-rich, vapor-rich, $CO_2-bearing$ and halite-bearing inclusions. These four types of inclusion intimately associated on a microscopic scale and indicate condensing or boiling of ore fluid during mineralization. Homogenization temperature of coexisting fluid inclusions are mostly in the range of 350 to $450^{\circ}C$. High salinity fluid contains 28.6 to 48.4 weight percent NaCI equivalent and moderate salinity fluid cotains 0.5 to 12.5 weight percent NaCl equivalent. Pressure estimated from $CO_2$ mole fraction of $CO_2-bearing$ inclusion range 160 to 375 bars. The Kigu copper deposits is a fissure filling copper vein developed 500 m south from the Keumryong deposits. Mineralogy and fluid inclusion data of the Kigu deposits are similar to that of the Keumryeong deposits. Homogenization temperature of fluid inclusions from the Kigu deposits are reasonable agreement with temperature estimated from sulfidation curve of cubanite-chalcopyrite-pyrite-pyrrhotite and pyrite-pyrrhotite mineral assemblages. Not only mineral occurrence and wall rock alteration in the Keumryeong deposits but also fluid inclusion data such as temperature, salinity, pressure and boiling evidences are similar to those of porphyry copper deposits.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.137-146
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• 2014

The geology of the study area which is located in Samkoe-dong, Dong-gu, Daejeon city comprises black slate, limestone, and pebble-bearing phyllitic rock as meta-sedimentary rocks; and biotite granite and quartz porphyry intrusions. Face mapping revealed sliding in three or four sites of contained coaly slate, where the dip of the foliation and other discontinuities is parallel to the surface slope. The cause of the slope sliding is this parallelism as well as the swelling of the coaly slate when wet. In contrast, the slop on the opposite side of the road is relatively stable because the dip of the foliation and other discontinuities are oblique or normal to the surface slope. To ensure slope stability, a cut-and-cover tunnel was designed and constructed for the new road.

• 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.40 no.1 s.182
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• pp.1-14
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• 2007

The Guemseong mine is located near the southern margin of the Jurassic Jecheon granitoids collectively with the Cambro-Ordovician mixed dolostone-limestone series of the Yeongweol Group, Choseon Supergroup. Here, two spatially distinct types of skarn formation have been observed. The upper transitional skarn is the calcic Mo skarn which has the mineral assemblage of $garnet+hedenbergite+epidote{\pm}wollastonite{\pm}magnetite{\pm}hematite{\pm}amphibole{\pm}chlorite{\pm}vesuvianite$ within the calcite marble. On the other hand, the lower proximal skarn occurs as a discordant magnesian Fe skarn at the contact of Mo-bearing aplitic cupolas with unidirectional solidification texture(UST) within the dolomitic marble. The magnesian Fe skarn has the mineral assemlage $olivine+diopside+magnetite+tremolite+serpentine+talc+chlorite{\pm}phlogopite$. The formation of two different types of skarn and ore mineralization in Geumseong mine have been attributed to multistage and complex metasomatic replacements that ultimately resulted in silicate-oxide-sulfide sequence of metasomatism. An early prograde stage with anhydrous skarn minerals such as olivine, clinopyroxene and/or garnet with magnetite, formed from high temperature (about $500^{\circ}\;to\;400^{\circ}C$) at an environmental condition of low $CO_2$ fugacity ($XCO_2<0.1$) and 0.5 kbar. The later retrograde stage with hydrous silicates such as amphibole, serpentine, phlogopite, epidote and chlorite with molybdenite or hematite, termed from relatively lower temperature (about $400^{\circ}\;to\;300^{\circ}C$).

• Economic and Environmental Geology
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• v.49 no.5
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• pp.389-410
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• 2016

Wide ranges of fission-track (FT) ages were obtained from the Jurassic granite batholith in Jeonju-Gimje-Jeongeup area, southwestern Okcheon Belt: sphene=158~70 Ma; zircon=127~71 Ma; apatite=72~46 Ma. Thermochronological analyses based on undisturbed primary cooling and reset or partially-reduced FT ages, and some track-length data reveal complicated thermal histories of the granite. The overall cooling of the batholith is characterized by a relatively rapid earlier-cooling (${\sim}20^{\circ}/Ma$) to $300^{\circ}C$ isotherm since its crystallization and a very slow later-cooling ($2.0{\sim}1.5^{\circ}/Ma$) through the $300^{\circ}C-200^{\circ}C-100^{\circ}C$ isotherms to the present surface temperature. It is indicated that the large part of Jurassic granitic body experienced different level of elevated temperatures at least above $170^{\circ}C$ (maximum>$330^{\circ}C$) by a series of igneous activities in late Cretaceous. Consistent FT zircon ages from duplicate measurements for two sites of later igneous bodies define their formation ages: e.g., quartz porphyry=$73{\pm}3Ma$; diorite=$73{\pm}2Ma$; rhyolite=$72{\pm}3Ma$; feldspar porphyry=$78{\pm}4Ma$ (total weighted average=$73{\pm}3Ma$). Intrusions of these later igneous bodies and pegmatitic dyke swarms might play important roles in later thermal rise over the study area including hot-spring districts (e.g., Hwasim, Jukrim, Mogyokri, Hoebong etc.). On the basis of an assumption that the latercooling of granite batholith was essentially controlled by the denudation of overlying crust, the uplift since early Cretaceous was very slow with a mean rate of ~0.05 mm/year (i.e., ~50 m/Ma). Estimates of total uplifts since 100 Ma, 70 Ma and 40 Ma to present-day are ~5 km, ~3.5 km and ~2 km, respectively. The consistent values of total uplifts from different locations may suggest a regional plateau uplift with a uniform rate over the whole granitic body.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.179-189
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• 2002

The Geology of the Shizhuyuan W-Sn-Bi-Mo deposits, situated 16 Ian southeast of Chengzhou City, Hunan Province, China, consist of Proterozoic metasedimentary rocks, Devonian carbonate rocks, Jurassic granitic rocks, Cretaceous granite porphyry and ultramafic dykes. The Shizhuyuan polymetallic deposits were associated with medium- to coarse-grained biotite granite of stage I. According to occurrences of ore body, ore minerals and assemblages, they might be classified into three stages such as skarn, greisen and hydrothernlal stages. The skarn is mainly calcic skarn, which develops around the Qianlishan granite, and consists of garnet, pyroxene, vesuvianite, wollastonite, amphibolite, fluorite, epidote, calcite, scheelite, wolframite, bismuthinite, molybdenite, cassiterite, native bismuth, unidetified Bi- Te-S system mineral, magnetite, and hematite. The greisen was related to residual fluid of medium- to coarse-grained biotite granite, and is classified into planar and vein types. It is composed of quartz, feldspar, muscovite, chlorite, tourmaline, topaz, apatite, beryl, scheelite, wolframite, bismuthinite, molybdenite, cassiterite, native bismuth, unknown uranium mineral, unknown REE mineral, pyrite, magnetite, and chalcopyrite with minor hematite. The hydrothermal stage was related to Cretaceous porphyry, and consist of quartz, pyrite and chalcopyrite. Scheelite shows a zonal texture, and higher MoO) content as 9.17% in central part. Wolframite is WO); 71.20 to 77.37 wt.%, FeO; 9.37 to 18.40 wt.%, MnO; 8.17 to 15.31 wt.% and CaO; 0.01 to 4.82 wt.%. FeO contents of cassiterite are 0.49 to 4.75 wt.%, and show higher contents (4.]7 to 4.75 wt.%) in skarn stage (Stage I). Te and Se contents of native bismuth range from 0.00 to 1.06 wt.% and from 0.00 to 0.57 wt.%, respectively. Unidentified Bi-Te-S system mineral is Bi; 78.62 to 80.75 wt.%, Te; 12.26 to 14.76 wt.%, Cu; 0.00 to 0.42 wt.%, S; 5.68 to 6.84 wt.%, Se; 0.44 to 0.78 wt.%.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.139-144
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• 2000

This study was conducted to obtain the basic information to increase the practical use of soil survey data through the subdividing of valley shapes with soil sequences due to different parent rocks, and to study the relationship between the valley shapes and parent rock. The various rocks such as sedimentary(gray shale and sand stone) and igneous rocks(granite, granite gneiss and andesite porphyry) which are the major parent rocks in Yeongnam area were investigated. The characteristics of valleys formed and the kinds of soils derived from different rocks were analysed by using aerial photographs and topographical maps scaled 1:5,000. The rill density in igneous rock area was as high as 40. But the rill bifurcation ratio of first order stream was higher in the sedimentary than the igneous rocks except granite area. The mean slope of valleys in igneous areas was about 8%, which was higher than that of the sedimentary areas. The variability of valley width in the complexly metamorphosed rock, such as granite gneiss, and andesite porphyry, was greater than in sedimentary and in granite rocks. Based on the variability of valley widths and valley slopes, it was possible to classify the valleys into two types. The "Uterus-shaped valleys" had wide variability of valley width and were located in the areas of granite gneiss and andesite porphry rocks. while the "Roots-shaped valleys" had narrow variability of valley width and were located in the sedimentary areas. "Uterus-shaped valleys" were typified by having land forms of mountain foot slopes and alluvial fans, and the soil drainage sequences also had complexities. So that, we concluded that the variability of valley width and valley slopes was associated with kinds of parent rocks and metamorphism which influences soil sequence and characteristics.

• Korean Journal of Mineralogy and Petrology
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• v.37 no.2
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• pp.77-85
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• 2024

Recently, the world has been declaring global carbon neutrality to curb carbon emissions, a major factor in global warming. Therfore, high-tech and clean energy industries such as renewable energy, electric vehicles, batteries, and semiconductors are rapidly developing. The Korean government selected total 33 critical minerals on based of evaluating the supply risk and economic impact of raw minerals essential for national high-tech industries (semiconductors, secondary battery, etc). Among these critical minerals, Copper, Zinc and lead have been used as basic materials in human life from the past to the present and in addition, they are currently used as an essential material for mobile phones, electric vehicles, and batteries. So, I would like to introduce the Las Bambas copper mine within Apurimac porphyry copper metallogenic belt of Peru, which have the world's 2^nd (copper), 4^th (zinc) and 5^th (lead) largest reserves of these critical minerals. Las Bambas copper mine is the world's largest mine with copper reserves of more than 1 billion tons and is joint venture project mine invested by MMG (Minerals and Metals Group, 62.5%), Guoxin international investment company (22.5%) and CITIC metal company (15.0%). This mine mainly produces copper and also produces gold, silver and molybdenum as a by-product. The ore grade of this mine has 0.77% Cu, 0.06 g/t Au, 3.93 g/t Ag and 178 ppm Mo. Mineral resource and ore reserve of this mine have 10.5 million ton Cu (0.61% Cu) and 6.9 million ton Cu (0.73% Cu). So, this mine life is about more than 20 years. The copper mineralization of this mine occurs as skarn type and vein type related with lower limestone of Ferrobamba formation and Cenozoic monzonites.

• Economic and Environmental Geology
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• v.9 no.4
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• pp.177-212
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• 1976

The Shap granite encloses well developed quartz veins and veinlets containing molybdenite in association with other ore sulphide minerals. The preliminary study of the geochemical aspects of the granite stock and mineralisation of molybdenite in comparison with the porphyry deposits is carried out; the distribution of major, minor and ore metal elements in wall rocks, altered envelope and veins, and the molybdenum mineralisation, mainly in connexion with hydrothermal alteration are discussed. The molybdenite and other ore mineralisation, especially bismuthinite and chalcopyrite, are spatially closely related to the hydrothermal alteration adjacent to the veinings, and are dominant where the strong orthoclase alteration has taken place. A pattern of alteration and mineralisation can be recognised and forms the basic for the subdivision of the quarry into several distinct zones, which correspond with the sequence of alteration and mineralisation. The veins, veinlets and their alteration haloes can be further subdivided into a series of concentric zones.