• 암석학회지
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• 제18권2호
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• pp.171-179
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• 2009

북한의 평안분지 서부의 증산-평원지역에 분포하는 선캠브리아 기저를 이루는 화강편마암에서 분리한 저콘에 대하여 LA-ICP-MS U-Pb 연대측정을 실시하였다. 그 결과 $1,873{\pm}19(2{\sigma})$Ma의 일치곡선연령을 구하였으며 이는 고원생대의 화강암질 화성활동을 나타낸다. 한반도의 선캠브리아 기저지각 암석들로부터 SHRIMP 및 LA-ICP-MS 등의 방법에 의해 구한 최근의 정밀한 연대자료를 살펴보면 영남육괴, 경기육괴, 낭림육괴 등 한반도 전역에서 이 화강편마암과 마찬가지로 ${\sim}$1870 Ma의 연령이 가장 빈도 높게 보고되고 있다. 이 시기의 지질사건들은 지역에 따라 화강암질 화성활동뿐만 아니라 고온의 광역변성작용도 함께 나타나는 것으로 해석되고 있다. 인접한 중국의 북중국과 남중국지괴들 역시 유사한 시기의 화성 및 변성활동들이 보고되고 있으며 한반도의 선캠브리아 육괴들이 북중국과 남중국 어느 지괴와 대비되는지는 더 많은 자료와 연구가 필요하다.

• 자원환경지질
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• 제17권4호
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• pp.299-314
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• 1984

The Yeongdo Island in Busan City is a remnant of the latest Cretaceous volcano, and consists geologically of andesites, rhyolite tuff, pelitic and psammitic hornfelses, lapilli rhyodacite tuff of the Yucheon Group, felsite and felsite porphyry of the Bulgugsa intrusives, and Holocene sediments in ascending order. The hornfelses are bound to the Taejongdae Formation. The stratigraphic position of the Formation is determined definitely into the Yucheon Group, thus the geologic age is approximately the same with the volcanic rocks of the Group. The sediments had been thermally metamorphosed to make pelitic and psammitic hornfelses of the albite epidote hornfels facies by the effects of active hydrothermal circulation, vaporization, and hybridization of andesitic solution, or of basification of acidic intrusives. Thus, on occasion, those hornfelses are not used to be distinguished from the andesitic rocks in the southeastern part of the Korean peninsula. The paleocurrent direction determined from several cross-beddings of the Taejongdae Formation is suggested to be from southwest to northeast. Orbicular rocks occur in hornfelsed rhyolite tuff, pelitic- and psammitic-hornfelses, and felsite porphyry at a lot of outcrops in the area of southwestern shoreline of the Yeongdo Island. Orbicules in rhyolite tuff and hornfels in the island might have originated from diffusion processes of metasomatic metamorphism carried out by hydrothermal solution rised from the intrusive adamellite which may be emplaced deeply under the Yeongdo volcanics. Those orbicules are due to metasomatic, secondary, and epigenetic origin. Proto-, multi-shelled, and multi-cored orbicules are described in the orbicular tuff. But multi-cored orbicules are not found in the orbicular fornfels. 250 tuff-orbicules numbered sporadically are in $20,000m^2$ area of the locality of orbicular tuff. About 60 hornfels-orbicules occurred sporadically are in $1,700m^2$ area of the locality of orbicular hornfels in the Taejongdae Formation. Orbicules in felsite porphyry might have originated by diffusion reaction between xenoliths and a quiescent zone in felsite porphyry magma. Those are of igneous, primary, and syngenetic origin.

• 자원환경지질
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• 제31권4호
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• pp.311-324
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• 1998

Paleomagnetic study is carried out to investigate the possibility of remagnetization by dikes in the Cretaceous Gyeongsang Basin. We selected a site for a contact test as a preliminary study, and collected 41 core samples (7 from andesitic dike, 17 from sedimentary rock on the left side of dike and 17 from sedimentary rock on the right side). Magnetite was responsible for the remagnetization based on microscopic observation and demagnetization analysis. Although the increasement of magnetic susceptibility appears on both sides about 100 cm from the dike, the increment of NRM intensity was obtained from the specimens on the left side only. This is interpreted that the size of magnetite newly formed is dominated by superparamagnetic grains in the right side, but by larger than single-domain grains in the left. Reversed polarity component remagnetized by intrusion of dike was also found only for core samples from 116 cm left side of dike but abscent from right side indicating the remagnetization by the dike depends on the geometric shape and width of the dike, which is supported by field observations. The content of epidote is well correlated with remagnetization, and indicates the hydrothermal alteration/metameorphism was activated by the intrusion. We concluded that the above evidences in this study further support thermally-activated chemical origin of the remagnetization with meager contribution of contact metamorphism, and that any significant evidence of regional-scaled remagnetization was not found in the study area.

• 한국지구과학회지
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• 제22권6호
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• pp.548-557
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• 2001

충남 예산지구 활석광상지역에는 선캄브리아기의 유구편마암을 관입하고 쥬라기 흑운모화강암과 백악기의 산성 및 염기성 암맥의 관입을 받은 시대미상의 초염기성암체가 있다. 이 초염기성암체는 주로 사문암이고, 소량의 각섬암과 주로 사문암으로부터 형성된 활석광체를 포함한다. 이 사문암들은 사문석 반정과 layering의 발달정도에 따라 S1 ${\sim}$ S5의 5개 암석단위로 구분된다. 그러나 이들의 구성광물 및 화학조성들이 유사한 것으로 보아 사문암의 기원암은 동일마그마 기원의 감람암(dunite와 pyroxene peridotite)으로 해석된다. 사문암의 기원암인 감람암은 유구편마암이 받은 각섬암상의 광역변성작용시에 사문석화작용을 받아 사문암으로 되었고, 이 사문암으로부터의 주 활석화작용은 파쇄대를 따라 상승한 열수에 의한 열수변질작용으로 해석된다.

• 암석학회지
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• 제2권2호
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• pp.63-73
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• 1993

The assemblage epidote and grandite garnet occurs in low-to medium-grade metabasites and calc schists of various geotectonic settings and in hydrothermally altered calcareous rocks in skarn deposits. The compositions of sixteen epidote-garnet paris have been analysed by means of electron microprobe. Al-Fe partitioning between coexisting grandite garnet and epidote is considered and measured at the grain boundaries on the supposition that the surface equilibrium was maintained in the following exchange reaction: 2$Ca_2Al_3Si_3O_12$(OH)+$Ca_3Fe_2Si_3O_12$=2$Ca_2A_l2FeSi_3O_12$(OH)+$Ca_3Al_2Si_3O_12$ Partition coefficients confirms the differences in thermal conditions between low-grade and medium-grade metamorphic rocks. $K_D$ values ($X_{$CO_2$}$=($Fe^{+3}$/Al)$^{Ep}$/($Fe^{+3}$/Al)$^{Gr}$, where Fe=$Fe^{+3}$) from greenschist facies rocks of the estimated metamorphic temperatures, 330~$390^{\circ}C$, range approximately between 0.02 and 0.17. Epidote-amphibolite facies rocks and calcareous skarns of the estimated temperatures, 400~$550^{\circ}C$, have $K_D$ values between 0.24 and 0.37. $K_D$ values from the rocks of the temperatures, 640~$700^{\circ}C$, range nearly between 0.58 and 0.75. The diagrams in Figs. 2 and 3 can serve as a mineralogic thermometer for relatively shallow rocks, assuming that the pressure dependence of partition coefficients for the iron-exchange reaction in the two minerals can be neglected.

• 자원환경지질
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• 제11권4호
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• pp.169-182
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• 1978

The Weolagsan area consists of four units; (1) Low grade meta-sediments of the upper members of Ogcheon age unknown group such as Changri (mainly black slate and phyllitic rock), Majeonri (mainly alternation of slate, limestone and chert) and Hwanggangri Formation (pebble bearing phyllitic sediments); (2) Samtaesan Formation of Chosun System of Ordovician; (3) So called meta-volcanics and (4) Weolagsan Granite and its associations which intruded above mentioned meta-sediments and meta-volcanics. This study was focused to know the Woelagsan granite and its metasomatic effects to the country rocks petrographically and petrochemically. According to the field survey, microscopic work and some chemical analysis, the granite is a "normal granite" based on the Streckeisen's classification and belongs to a mass of the Central-zone younger group in Ogcheon geosynclinal belt. The granite metasomatized the country rocks along its northern contact zone. Zone of calcareous and cherty rocks (Majeonri formation) was silicified partly and skarned locally at the contact with the granite. The chemical analysis of the zone show no difinite variations in contents of $SiO_2$ and CaO with the distance from the granite. It seems to be indicated that the silicification of this part was not so metasomatized by the granite body, but thermally affected as much as to be partially remelted in the specific parts of the formations. Meta-volcanic rock zone was slightly chloritized near contact with the granite. Limestone of Samtaesan Formation was silicified and skarned along the contact zone by the granite body. The chemical analysis of the zone show some noticiable changes in compositions of $SiO_2$ and CaO with distance from the granite boundary. It can be imagined that the silicification of this zone was metasomatically originated by Woelagsan Granite. According to chemical analysis on several trace elements, the ratio of Zn/Cr and Ni/Cr are relatively higher than that of Cu/Cr in the above mentioned silicified zones. Generally the variation of these metal elements in the zones tend to be regular with distance from the granite body.

• 한국화재소방학회논문지
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• 제26권2호
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• pp.11-16
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• 2012

본 연구에서는 정확한 화재원인 분석 및 사기범죄 여부 확인을 위하여 극초단파를 직접 폴더형 휴대전화에 조사하고, 이때 발생되는 휴대전화의 손상형태를 분석하였다. 극초단파 조사를 위하여 전자레인지를 이용하였으며, 전자레인지의 마그네트론에서 발생되는 2.45 GHz의 극초단파가 휴대전화에 인가될 때 휴대전화의 손상형태를 분석하였다. 실험 결과, 휴대전화에 극초단파를 조사하는 경우, 조사 시간이 길어짐에 따라 심하게 손상되는 경향을 나타내었으며, 특히, 폴더의 힌지 부분 및 인테나 부분과 같이 금속이 설치되는 부분이 심하게 열변형되는 결과를 나타내었다. 휴대전화의 배터리 부분은 외함이 열변형되는 것 이외에 배터리의 손상이나 폭발 등은 발생되지 않는 것으로 평가되었다.

• 한국광물학회:학술대회논문집
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• 한국암석학회.한국광물학회 2000년도 공동학술발표회 논문집
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• pp.24-24
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• 2000

We studied about petrological characteristics of the Bangeujin granite belongs to porphyritic biotite granite, petrogenesis of the enclaves in the granite and contact metamorphism of the sedimentary rock around the granite. The enclaves in the granite are concentrated in the eastern part of the Mipo fault but in the western part, these are rare. The enclaves can be divided into three types according to the petrographical characteristics. These three types are: (1) enclaves having few phenocrysts and fine grained igneous texture and ellipsoid is predominant; (2) enclaves similar In petrographical characteristics and having many phenocrysts considered as being originated from the granitic host rock; and (3) enclaves corresponding to granite in mode composition, having large phenocrysts and of which the matrix is corresponding to fine granular. First two types are correspond to mafic micro granular enclaves and the third is corresponds to felsic microgranular enclaves. In addition, the felsic microgranular enclaves capture the mafic microgranular enclaves. The fact that the compositions of biotite and plagioclase in the enclaves are nearly identical with those of biotite and plagioclase in the granitic host rock is considered as the results of supporting magma mingling. The major elements show well the linear variations as the SiOz$.$ content increases. The rare earth elements content decrease with increasing SiOz content, interpreted as the results of magma mingling. Therefore, we can conclude that the Bangeujin granite captured the felsic microgranular enclaves formed by collapse of early chilled margin during the crystallization and there was magma mingling by the injection of the mafic magma after that time. In addition, these aspects are predominant in the eastern part of the Mipo fault is considered as related to the fault movement.vement.

• 자원환경지질
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• 제15권4호
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• pp.189-204
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• 1982

The Geodo mine is located in the southern limb of the Hambaeg syncline. Geology of the area consists of Paleozoic-Mesozoic sedimentary Rocks and Cretaceous igneous rocks. The important igneous rocks presumably related to skarnization and ore mineralization in the area, are the early granodiorite and the late porphyritic granodiorite. Two mineralogical types of ore deposits are recognized in the area. They are the Fe-Cu deposits in the Myobong formation and the Au-Bi-Cu deposits in the Hwajeol formation. Contact metamorphism due to granodiorite intrusion includes hornfelsization, exoskarnization and endoskarnization. Wall-rock alterations related to the Fe mineralization are grouped into the hydrothermal replacement skarnization and the hydrothermal filling skarnization. Another hydrothermal alteration is associated with the Cu mineralization. Various mineralogical analyses have been applied for the identification of minerals. They include optical microscopy, chemical analysis, etching test, X-ray diffraction, and infrared absorption spectroscopic analyses. The ore minerals in these ore deposits are classified into two groups;hypogene and supergene minerals. Hypogene minerals consist of magnetite, pyrite, chalcopyrite, and chalcocite. Supergene minerals consist of chalcocite, bornite, and geothite. Ore minerals show various kinds of ore texture: open-space filling, exsolution, replacement, and cementation texture. The gangue minerals consist of quartz, diopside, epidote, garnet and plagioclase in the hornfelsic zone, garnet, diopside, scapolite, actinolite, sericite, chlorite, quartz, and calcite in the skarn zone, and, epidote, chlorite, sericite, quartz, and calcite in the late hydrothermal alteration zone. This study shows that the Fe-Cu deposits are of metasomatic pipe type with the later hydrothermal fillings, and the Au-Bi-Cu deposits are of hydrothermal fissure-filling type. The mineralization is probably related to the intrusion of porphyritic granite.

• 자원환경지질
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• 제29권1호
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• pp.25-33
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• 1996

Stable isotopic ratios of the carbonate rocks and chemical compositions of the matrix of pebble bearing phyllitic rocks known as the Hwanggangri Formation, which are in hot debate on their origin such as tillite, debris flow and turbidite, were determined to interpret their depositional environment. Argillaceous matrix of the pebble bearing phyllitic rocks has a high content of CaO (av. 19.5%) and MgO (av. 8.3%), corresponding to calcareous sandy shale. No difference of chemical compositions including trace elements and REE is in the matrices between the Hwanggangri and the Kunjasan Formations. Carbonate rocks from the Okchon zone and outside of the zone range $-2.5{\sim}+6.1$‰ in ${\delta}^{13}C$ and $+5.8{\sim}+25.9$‰ in ${\delta}^{18}O$, indicating normal marine limestone. However, unusally $^{13}C$ enriched carbonate rocks might be deposited in the highly evaporated sedimentary basin. A wide variation of ${\delta}^{18}O$ values is responsible for metamorphism with a $^{18}O$ depleted meteoric water. Isotopic equilibrium temperatures by graphite-calcite geothermometer show a higher metamorphic temperature ($547{\sim}589^{\circ}C$) in the Okchon zone than those ($265{\sim}292^{\circ}C$) in the Samtaesan Formation of the Chosun group. Rhythmic alternation of relatively thin shale with thin limestone in the Kounri Formation is not cherty layer but thin limesilicate bed by metasomatic replacement. Judging from the isotopic and chemical compositions of the carbonate rocks and calcareous matrix of the pebble bearing phyllitic rocks, the Hwangganari Formation was deposited in the shallow marine environment favorable to debris flow.