• The Journal of Engineering Geology
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• v.24 no.2
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• pp.227-235
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• 2014

The deformation modulus is one of the essential factors in determining ground behavior and safety during tunnel excavation. In this study, we conducted a back-analysis using crown settlements measured during tunnel excavation, using a horizontal inclinometer on a fault zone of pegmatite, and calculated the deformation modulus of the fault zone. This deformation modulus calculation was then compared with deformation moduli found through established relationships that use the correlation between RMR and the deformation modulus, as well as the results of pressure-meter tests. The deformation moduli calculated by back-analysis differs significantly from the deformation moduli determined through established relationships, as well as the results from pressure-meter tests conducted across the study area. Furthermore, the maximum crown settlements derived from numerical analysis conducted by applying deformation moduli determined by these established relationships and the pressure-meter tests produced noticeable differences. This result indicates that in the case of a weak rock mass, such as a fault zone, it is inappropriate to estimate the deformation modulus using preexisting relationships, and caution must be taken when considering the geological and geotechnical characteristics of weak rock.

• Journal of the Mineralogical Society of Korea
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• v.28 no.1
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• pp.51-60
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• 2015

We applied gemological analytical approaches on Aquamarine from the Gilgit-Baltistan of Northern Areas, Pakistan. The standard gemological testing indicates that they are consistent with general characteristics of natural aquamarines. We have identified the inclusions of Tantalite-Mn by Raman analysis. It indicates that they occurs in association with the veins of Be-rich coarse pegmatite. And the results of chemical analyses, infrared absorption spectroscopy and Raman spectroscopy indicate that $H_2O$ molecules in channel mostly exist in Type-I and a little Type-II with low alkali ion. The comparison of relative peak intensity of FT-IR analysis can be used for prediction of $Na_2O$ content within not only emerald but also aquamarine.

• Economic and Environmental Geology
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• v.46 no.5
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• pp.455-468
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• 2013

We performed reconnaissance survey on Dashinchilen Nb-Ta REE area and Sant Cu area which are located in southeastern part of Khangai rare metals mineralized belt. In Dashinchilen area, Nb and Ta have been found in pegmatitic granite that is largely distributed in the survey area and muscovite in pegmatite which is an intrusion in paleozoic sedimentary rocks which are mostly composed of sandstone. While grades of Nb and Ta are not high, an outcrop that has high Th and U contents (542 ppm of Th and 56.9 ppm of U) has been found. Average and maximum REE contents in the survey area is three times and seven times, respectively, larger than average REE contents in the crust of the Earth. In Sant area, copper oxides such as malachite has been found in quartzite in paleozoic sedimentary rocks. A sedimentary rock formation that has high grade of Mn (12.4-34.6 %) has been found in the survey area. This sedimentary rock formation is the same formation with that of Ugii Nuur Fe-Mn mineralization which is located about 200 km northwest of the survey area. Average and maximum REE contents in the survey area is two and half times and seven times, respectively, larger than average REE contents in the crust of the Earth. According to the factor analysis for the data of the geochemical analysis, Nb and Ta in Dashinchilen area are highly correlated with muscovite and Cu in Sant area is highly correlated with Mo, Sn, and Bi. Furthermore, the factor analysis results show that Fe in Sant area was deposited with rare earth elements.

• Journal of Conservation Science
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• v.26 no.3
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• pp.277-294
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• 2010

The Seosanmaaesamjonbulsang (National Treasure No. 84) consists of light gray and coarse to mediumgrained biotite granite with partly developed pegmatite and quartz vein. The host rock is divided into dozens of rock blocks with various shape along irregular discontinuity plane. The evaluation results of discontinuity systems reveal that the host rock were exposed to instable sloping environments. Results of deterioration diagnosis show that the degree of damage has been made worse by physical weathering and surface discoloration laying stress on part that vertical and horizontal joints are massed. Generally, deterioration rate of the triad Buddha surface cover with 42.7%, however, the rate of physical weathering and surface discoloration are subdivided to 9.6% and 33.1%, respectively. Ultrasonic measurements indicate that the triad Buddha was reached highly weathered grade in general. And the rock material was weaken to show low velocity zone of 1,000m/s along irregular joint systems. Indoor and outdoor mean relative humidity of the shelter was recorded more than 70% during every season, and high frequency appears in high relative humidity range over 95%. Such environments seem to have produced dew condensation on the rock surface with rainfall and supply water, promoted physical, chemical and biological weathering along crack and joint, resulting in high permeation of water and percentage of water content. Therefore, it is judged that for scientific conservation of the triad Buddha it needs environment control through persistent preservation environment monitoring including water problem.

• The Journal of the Petrological Society of Korea
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• v.8 no.1
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• pp.14-23
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• 1999

The northeastern part of the Gyeongsang Basin is widely covered by the Cretaceous Hayang Group (Aptian to Albian). The Hayang Group consists of the IIjig. Hupyeongdong, Jeomgog, and Sagog formations. Heavy mineral analysis was carried out to define the possible source rocks of the Haynag Group snadstones. Heavy minerals separated from IIjig, Hupyeongdong, and Jeomgog sandstones are hematite, ilmenite, leucoxene, magnetite, pyrite, actinolite, andalusite, apatite, biotite, chlorite, epidote, garnet, hornblende, kyanite, monazite, muscovite, rutile, sphene, spinel, staurolite, tourmaline, and zircon. Based on their close association and sensitiveness, the heavy mineral assemblages can be classified into 6 syutes: 1)apatite-green tourmaline-sphene-colorless/yellowish zircon; 2) colorless garnet-epidote-rutile-brown tourmaline; 3) rounded purple zircon-rounded tourmaline-rounded rutile; 4) augite-hornblende-color- less zircon; 5) epidote-garnet-sphene; and 6) blue tourmaline. The possible source rocks corresponding to each assemblage are 1) granitic rocks; 2) metamorphic rocks (schist and gneiss) ; 3) older sedimentary rocks; 4) andesitic rocks; 5) metamorphosed impure limestone; and 6) pegmatite, respectively. Previous paleocurrent data suggest that the sediments of the study area were mainly derived from the northeastern to southeastern directions. Thus, the most possible source areas would be the east extension part of the sobaegsan metamorphic complex to the northeast and the Cheongsong Ridge to the southeast.

• Journal of the Korean earth science society
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• v.21 no.3
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• pp.302-314
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• 2000

Keumseong area in the southern part of the Jecheon city, the Ogcheon Belt, consists of Precambrian Dangdusan Metamorphic Complex, Dori Formation of the Choseon Supergroup, and Jurassic Jecheon Granite. The Dangdusan Metamorphic Complex consists of quartz schist, mica schist. quartzite and pegmatite. The Dori Formation is composed of mainly laminated limestone. The rocks in the study area have been undergone at least three phases of deformations since Paleozoic period. The Dangdusan Metamorphic Complex is outcrop at three areas in the study area, which are exposed along the faults and occurred as inlier within the Dori Formation. Previous authors interpreted the uplift of the Dangdusan Metamorphic Complex by the Dangdusan Fault, but we could not find any evidences related to the Dangdusan Fault. Thus, we interpret the uplift of the Dangdusan Metamorphic Complex due to the D$_2$ Weolgulri and Dangdusan thrusts and post-D$_2$ Jungbodeul, Kokyo and Jungjeonri faults. The uplift of the Busan Metamorphic Complex to the west of the study area was interpreted by ductile deformation. However, the Dangdusan Metamorphic Complex is formed by brittle thrusts and faults in this study. According to deformation sequence, the characters of deformations in the Choseon and Ogcheon suprergroups had been changed from ductile to brittle deformations through the time. Therefore, we interpret the Dangdusan Metamorphic Complex is exposed later than the Busan Metamorphic Complex.

• Economic and Environmental Geology
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• v.13 no.3
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• pp.167-184
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• 1980

The granitic plutons associated with Ogcheon geosynclinal zone can be grouped into three different subzones; SE-Subzone for the migmatitic and schistose granites of the southeast margin, 101-181m.y. old; NW-Subzone for those of the northwest margin, 112-163m. y. old; and C-Subzone for those of central part of the zone, 63-183m.y. old. The intrusives in C-Subzone are further subdivided into the older, adamellite to granodiorite (148-183m.y. old) and the younger, perthitic granites (63-106m,y. old). The metallogenic distribution of South Korea suggests that, in the Ogcheon Zone, it is possible to delineate an elongated polymetallogenic province in the general orientation of the zone intimately related with the migmatite and plutonic zones mentioned. Moreover, the mineralization in the province was basically controlled by the patterns of local geology involving country rocks and related igneous bodies, that permit subdivision of the province into the following three parts: Northeast (NE) Province consists dominantly of thick Paleozoic calcareous sediments; Middle (M) Province is characterized by predominant argillaceous and partly calcareous sediments of Precambrian to Late Paleozoic age; and Southwest (SW) Province consisting mainly of volcanic and arenaceous sediments of Mesozoic age. The three different plutonic zones with three different country rock provinces above mentioned make a combination which consists of nine classes. Each class can be assumed to be characterized by specific mineralization type. In order to classify the mineralization types, the present study sampled twenty six ore deposits and mineralized areas in Ogcheon zone as shown figure 2; eight ore deposits from plutonic SE-Subzone, ten from the plutonic NE-Subzone and eight from the plutonic C-Subzone. The characteristics of the classes are as follows: NE-SE is predominant in Au-Ag vein and Sn-migmatite of katazonal occurrence; NE-C is most productive in Pb-Zn and remarkable in Fe contact deposit in mesozone and partly Pb-Zn-Cu skarn in limestone and subordinate in mesozone and partly Pb-Zn pipes; M-SE is considerable in Au-Ag vein and rare elements (Nb, Ta, etc.) of pegmatite; M-C is predominant in F-veins in epizone and Mo-W, Fe, Cu veins occur in replacement type; M-NW is productive in Fe metamorphic and skarn types, partly remarkable in Cu, Pb-Zn contact; SW-SE is barren in mineralization related to Jurassic igneous rocks; SW-C is predominant in alunite and pyrophyllite in tuffs; and SW-NW is scarece in Pb-Zn, Cu, As and Au-Ag veins.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.629-641
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• 2006

The Standing Buddha Statue in the Gwanchoksa temple consists of medium to coarse grained biotite granodiorite with dark grey color, and it has a week gneissosity along the pegmatite veins. The results of magnetic susceptibility and geochemical patterns of the host rock of Standing Buddha Statue and the basement rock suggest that both values are formed from the co-genetic magma with the same differentiation process. The CIAs of the basement rock and the Standing Buddha Statue are calculated to 51.43 and 50.86, and the WPIs are estimated 4.52 and 8.95, respectively. So the weathering potential from the host rock of Standing Buddha Statue and basement rock prove to be high. The Standing Buddha Statue is terribly damaged with physical weathering from deterioration and exfoliation, and are scattered with secondary pollutant and precipitate. Basement rock is also in danger of ground collapse because of irregularly developed discontinuity system. Most surface of Standing Buddha Statue is seriously discolored into yellowish brown and dark gray, or black precipitates are also formed. Moreover, it is heavily covered with crustose lichen, fungi and algae, or moss are also found. In order to control the influential factors with the complex deterioration of Standing Buddha Statue, it is needed to rearrange a site environments, and conservation scientific management is required to protect it from covering lichens, exfoliations and fractures.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.05a
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• pp.57-65
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• 2009

Selection of good mineralized area is a combination of the integration of all the available geo-scientific (i.e., geological, geochemical, and geophysical) information, extrapolation of likely features from known mineralized terrenes and the ability to be predictive. The time-space relationships of the hydrothermal deposits in the East Asia are closely related to the changing plate motions. Also, two distinctive hydrothermal systems during Mesozoic occurred in Korea: the Jurassic/Early Cretaceous deep-level ones during the Daebo orogeny and the Late Cretaceous/Tertiary shallow geothermal ones during the Bulguksa event. Both the Mesozoic geothermal system and the mineralization document a close spatial and temporal relationship with syn- to post-tectonic magmatism. The Jurassic mineral deposits were formed at the relatively high temperature and deep-crustal level from the mineralizing fluids characterized by the relatively homogeneous and similar ranges of ${\delta}^{18}O$ values, suggesting that ore-forming fluids were principally derived from spatially associated Jurassic granitoid and related pegmatite. Most of the Jurassic auriferous deposits (ca. 165-145 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, Late Cretaceous ferroalloy, base-metal and precious-metal deposits in the Taebaeksan, Okcheon and Gyeongsang basins occurred as vein, replacement, breccia-pipe, porphyry-style and skarn deposits. Diverse mineralization styles represent a spatial and temporal distinction between the proximal environment of sub-volcanic activity and the distal to transitional condition derived from volcanic environments. However, Cu (-Au) or Fe-Mo-W deposits are proximal to a magmatic source, whereas polymetallic or precious-metal deposits are more distal to transitional. Strike-slip faults and caldera-related fractures together with sub-volcanic activity are associated with major faults reactivated by a northward (oblique) to northwestward (orthogonal) convergence, and have played an important role in the formation of the Cretaceous Au-Ag lode deposits (ca. 110-45 Ma) under a continental arc setting. The temporal and spatial distinctions between the two typical Mesozoic deposit styles in Korea reflect a different thermal episodes (i.e., late orogenic and post-orogenic) and ore-forming fluids related to different depths of emplacement of magma (i.e., plutonic and sub-volcanic) due to regional changes in tectonic settings.

• The Journal of the Petrological Society of Korea
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• v.27 no.2
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• pp.85-96
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• 2018

The Neoproterozoic Gyemyeongsan Formation and the Mesozoic igneous rocks are distributed in the Eoraesan area, Chungju which is located in the northwestern part of Ogcheon metamorphic zone, Korea, and the rare earth element (REE) mineralized zone has been reported in the Gyemyeongsan Formation. We drew up the detailed geological map by the lithofacies classification, and measured the radioactivity values of the constituent rocks to understand the distribution and characteristics of the source rocks of REE ore body in this paper. It indicates that the Neoproterozoic Gyemyeongsan Formation is mainly composed of metapelitic rock, granitic gneiss, iron-bearing quartzite, metaplutonic acidic rock (banded type, fine-grained type, basic-bearing type, coarse-grained type), metavolcanic acidic rock, and the Mesozoic igneous rocks, which intruded it, are divided into pegmatite, biotite granite, gabbro, diorite, basic dyke. The constituent rocks of Gyemyeongsan Formation show a zonal distribution of mainly ENE trend, and the distribution of basic-bearing type of metaplutonic acidic rock (MPAR-B) is very similar to that of the previous researcher's REE ore body. The Mesozoic biotite granite is regionally distributed unlike the result of previous research. The radioactive value of MPAR-B, which has a range of 852~1217 cps (average 1039 cps), shows a maximum value among the constituent rocks. The maximum-density distribution of radioactive value also agrees with the distribution of MPAR-B. It suggests that the MPAR-B could be a source rock of the REE ore body.