• Journal of the Korean earth science society
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• v.21 no.3
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• pp.323-336
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• 2000

Ultramafic rocks in Choongnam area are mainly serpenitinites which are parent rock of talc and asbestos ore deposits. About 10 $^{\circ}$ NNE-trending parallel serpentinites masses occur as discontineous isolated lenticular intrusive bodies in Precambrian gneiss complex between Hongseong-Kwangcheon line and Onyang-Cheongyang line. The sizes of serpentinites vary from several centimeters to 1 kilometer in width and from several meters to 5 kilometers in length. The serpentinites show high SiO$_2$(39.99wt.% in average), MgO(38.46wt % in average), Cr(>1011ppm), Ni(>1660ppm), and Co(>80ppm). Most serpentinites contain serpentine more than 50%. Some serpentines contain original minerals such as olivine, pyroxene and chromite. Also, serpentinites body may contain a little serpentinized peridotite, and some talc and asbestos ore deposits. The original rocks of the serpentinites interpreted as Alpine type ultramafic rocks, and dunite and/or harzburgite which were originated from slightly depleted upper mantle(30${\sim}$40km deep), and emplaced in the crust through the large fault zones. It seems that main serpentinization from the original rocks was occurred during greenschist and/or amphibolite facies regional metamorphism in Choongnam area.

• Economic and Environmental Geology
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• v.30 no.5
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• pp.477-491
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• 1997

In the Bibong area of the western part of Chungcheongnam-do, ultramafic masses occur as discontinuous isolated lenticular bodies in the Precambrian Kyeonggi gneiss complex. They extend for about 200 m long to NNE directions which are parallel to fault lines in the gneiss complex. The ultramafic masses contact with the adjacent gneiss complex as steeply dipping faults. They are dunites and harzburgites and many of them are partially or completely serpentinized. The ultramafic rocks dominantly show protogranular, equigranular and equigranular-$m{\grave{o}}saic$ textures. They also show porphyroclastic (megacrystic) or recrystallized textures reflecting several stages of metamorphism. They contain varying amounts of olivine $(Fo_{89-92})$, enstatitic to bronzitic orthopyroxene, diopsidic clinopyroxene, tremolitic to pargasitic hornblende, and spinel with serpentine, talc, chlorite, calcite and magnetite. The ultramafic rocks have high magnesium numbers and transitional element contents, low alkali contents and show deplete REE patterns. Comparing with available data, geochemical and mineralogical characteristics shown in the ultramafic rocks of the Bibong area are similar to those of worldwide mantle xenoliths and orogenic related ultramafic rocks. The field evidences, petrographical, geochemical and mineralogical characteristics shown in the ultramafic rocks of the Bibong area are similar to alpine type ultramafic rocks emplaced into the crust by the faulting as mantle slab types. With the petrographical characteristics, these mineralogical compositions suggest that the ultramafic rocks of the Bibong area have experienced several stages of retrogressive metamorphism in a condition ranging from the upper amphibolite facies to greenschist facies.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.171-182
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• 1996

Quaternary Jungok basalts are distributed along the old Hantan river in Mid-Korean Peninsula. They were flowed out from Mt. Ori and Upland (680 m), and they formed narrow and long basalt plateau showing the layers of 10 to 20 meters in thickness and about 95 km in length. Fifty seven samples were collected from the study area, and sixteen rock samples were selected and analysed for major and trace elements. The analyzed samples have alkalic composition and show a relatively restricted variation in major element chemistry (except MgO), as comparing to the that of trace element. Based on major element chemistry, a quantitative modelling of fractional crystallization by multiple linear regression method suggests that the chemical evolution of the evolved rocks can be generated by fractionation of olivine, plagioc1ase, clinopyroxene, and magnetite in proportion of 56 : 25 : 17 : 2, respectively. The calculated trace element abundances by mineral proportions estimated from major element modelling, however, underestimate the incompatible element concentrations in the evolved rocks. According to the incompatible element abundances, simple fractional crystallization process has difficulty to explain the chemical variation of the evolved rocks. It seems that the other processes, which enrichment of incompatible elements can occure without concomitant changes in major element compositions, are needed in order to explain the chemical variation of the Jungok basalts. Thus, the major elements and compatible trace elements variations of the Jungok basalts are due to fractional crystallization, but the incompatible elements variation is due to fractional crystallization superimposed on already varying concentrations caused by slightly different degrees of melting of the same source, and/or due to periodic replenishment, tapping and fractionation(RTF) processes.

• The Journal of the Petrological Society of Korea
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• v.21 no.3
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• pp.277-285
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• 2012

Hawaiite which distributed in Sanjideungdae of Sarabong cinder cone and Biseokgeori area in northern part of Jeju island, contains phenocrysts of titanium-rich hornblende (kaersutite) and plagioclase with microphenocrysts of olivine, pyroxene and very small amounts of K-feldspar lath and apatite. Kaersutite is mostly euhedral or subhedral phenocrysts having opaque reaction rim. And kaersutite in Sanjideungdae area completely replaced to opaque minerals showing pseudomorph. Also it may be seen partly replacement of pyroxene by kaersutire as reaction rim. It is considered that hydration reaction had occurred with fluids. The crystallization pressure of kaersutite using pressure-$Al^T$ geobarometer is approximately 6.3 kb in Sanjideungdae area and 4.9 kb in Biseokgeori area, respectively. As a result, fluid injection to magma and crystallization of kaersutite of Sanjideungdae hawaiite is deeper than that of Biseokgeori hawaiite, and it was growed to phenocrysts through crystallization. It is estimated that kaersutite of Biseokgeori hawaiite originated from crystallization from the host magma, based on the euhedral nature of the phenocrysts and on the presence of apatite inclusions.

• Journal of the Korean earth science society
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• v.34 no.1
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• pp.28-40
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• 2013

This study examined the geochemical characteristics, equilibrium temperature and pressure conditions, and oxygen isotopic ratios of mantle xenoliths from the various geological sites of the Korean peninsula. The results are as follows: (1) The ultramafic xenoliths from the Korean peninsula mainly consist of typical high magnesium olivine (MgO : 49.12-50.95 wt.%, Mg value: 90.1-92.2), corresponding to worldwide Cenozoic ultramafic xenoliths in chemical compositions. (2) The pressure-temperature conditions of ultramafic xenoliths in the Korean peninsula are from 854 to $1016^{\circ}C$ and 4.6 to 24.4 kbar. (3) The oxygen isotopic ratios (${\delta}^{18}O$) for olivines in ultramafic xenoliths range from 5.06‰ to 5.51‰, which are relatively uniform oxygen isotopic values and overlapped by the values of N-MORB and upper mantle peridotite (${\delta}^{18}O$: $5.2{\pm}0.2$‰). However, olivines of the ultramafic xenoliths from the Baegdusan and Chejudo have a relatively wide ${\delta}^{18}O$ values ranging from 5.07 to 5.51‰ and 5.07 to 5.45‰, respectively. Based on the results, this study suggests that the high ${\delta}^{18}O$ signature of the Baegdusan xenoliths give a hint that ~5% of the oxygen in typical EM2 sources originally derived from recycled sediments.

• Journal of the Korean Electrochemical Society
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• v.10 no.3
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• pp.184-189
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• 2007

The importance of secondary battery industry is getting excited according to the development of battery industry as a high efficiency energy supplier of electronic machine of mobile information such as mobile phone, lap-top computer, PDA. It is rasing the interest about security of safety and high efficiency of cathode material for main part of secondary lithium battery. The cathode material which has been used like $LiCoO_2,\;LiMn_2O_4,\;LiNi_xCo_yMn_zO_2,\;LiNi_xCo_yM_zO_2$ (M=Al, Zr, Mg etc.,) the most typical material is $LiCoO_2$. But it is studying the development of substitute such as efficiency amelioration of $LiCoO_2$, thetiary element, olivine element because of the capacity of $LiCoO_2$, the matter of security; especially the betterment of efficiency, security research of safety has been actively processed in domestic and overseas about surface coating treatment of active cathode which is using oxide ($M_xO_3$). This study analyses side effect of battery according to increase of surface treatment, formation of precipitation for reagent condensation, non-reagent residue of oxide ($M_xO_3$) which is remains during the surface treatment of $LiCoO_2$; conducts study of new process, the consideration of the electrochemical property to improve oxide solution of mixing rate, mixture of surface treatment, dryness, calcinations conditionetc.

• The Journal of the Petrological Society of Korea
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• v.15 no.2 s.44
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• pp.90-105
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• 2006

The Cretaceous volcanic rocks in the study area represented by andesitic rocks occupy eastern part of the Kyeongsan Caldera. The volcanic rocks comprise andesite I, andesitic tuff, andesite II, and andesitic tuff breccia in their stratigraphic succession, and andesitic porphyry. Andesite I is distinguished from andesite II in their color, texture, phenocryst mineralogy and petrochemisty. In outcrops, andesite I is compact and dark-green, and andesite II is brick red in color and porphyritic in texture. In their phenocryst mineralogy, andesite I contains olivine phenocryst in addition to plagioclase and pyroxene which occur in both of andesites. Compared to andesite II, andesite I is higher in $SiO_2$ and $K_2O$ contents and lower in CaO, MgO, MnO, $TiO_2,\;Fe_2O_3$, and $P_2O_5$. Major elements petrochemistry shows that magma series of the volcanic rocks spread widely from calc-alkaline to alkaline series. On the other hand, immobile trace elements petrochemistry shows that the magma series is calc-alkaline without exception, suggesting that the volcanics has experienced more or less alkali enrichment after their eruption. Trace element diagrams for discrimination of tectonic setting show that the volcanics of the study area might be originated from calc-alkaline continental volcanic arc.

• The Journal of the Petrological Society of Korea
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• v.5 no.1
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• pp.66-83
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• 1996

We report petrography, mineral chemistry, and major and trace element chemistry for rare tholeiites in Cheju island where alkalic rocks predominate. Available age data indicate that the tholeiitic magmatism was younger than 0.49Ma, possibly younger than 0.17 Ma. The tholeiites are generally fine-grained, porphyritic rock and show intergranular texture with lath-shaped plagioclase ($An_{61-46}$), orthopyroxene (bronzite) and olivine ($Fo_{78-67}$). Characteristically, two kinds of clinopyroxene (pigeonite and augite) occur only in groundmass. The tholeiites have normative quartz and show limited compositional variations ($SiO_2$=51.0-52.5 wt%; Mg＃=54-60). Major and transitional metal element variations of tholeiites are distinct from those of alkaline rocks in MgO diagram, suggestingthat the two rock types cannot be simply related to differentiation process from the same magma. The ratios among $K_2O$, Rb, Ba, Nb and La are similar for both tholeiites and alkali basalts, however the ratios between the elements (P, Y and Yb) having an affinity with garnet and the above elements are higher for tholeiites than for alkali basalts. These trace element ratios suggest that the tholeiites and alkali basalts were produced by different degrees of partial melting from a similar sources material (garnet lherzolite mantle).

• The Journal of the Petrological Society of Korea
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• v.16 no.4
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• pp.217-232
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• 2007

The Puu Oo eruption in Hawaii since 1983 is one of the largest eruptions on Hawaii's volcanic history with prominent compositional variation ($5.6{\sim}10.1wt.%$ in MgO content). Although intense researches of Hawaiian eruption have been conducted for recent years, there is no up-to-date study on Puu Oo lavas that is erupting hot lavas today. in oder to obtain basic information on the geological characteristics of the eruption including any noticeable change in its petrological trend and magma dynamics, we applied several geological approaches such as field survey, systematic sampling, petrography, mineralogy, and geochemistry. Clinopyroxene and Plagioclase phenocrysts are rarely observed on the thin section, however Olivine crysts are much more obvious in the study area. It indicates that Puu Oo is early stage of magma differentiation. Variation diagram of whole rock composition shows that the elements such as $TiO_2,\;Al_2O_3,\;SiO_2$ and $Na_2O$ decrease with increasing MgO. In the trace element Sr, Y Zr and V versus $K_2O$, P18, P19 samples are plotted in primitive area. Variations of the Ni contents during $2003{\sim}2006$ may suggest a sudden change in magma composition probably caused by new magma injection.

• The Journal of the Petrological Society of Korea
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• v.25 no.4
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• pp.335-348
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• 2016

The fluvial Tamna Formation, consisting of conglomerate, sandstone and mudstone layers, is widely distributed in Jeiu Island. Various sizes of quartz crystals were identified from most of the Tamna Formation, including the mudstone layer. XRD analysis also shows that the mudstone layer is composed of various minerals, quartz, plagioclase, K-feldspar, mica, magnetite, hematite, olivine, amphibole, gibbsite, calcite, analcime and clay minerals such as illite, kaolinite, vermiculite, smectite, chlorite, $10{\AA}$-halloysite. There is a tendency showing that the more amount of kaolinite, vermiculite, and chlorite is present where the more amount of quartz crystals is present. It is likely that the main source materials contributing to the Tamna Formation were from the parental rocks containing abundant quartz grains, suggesting that the Tamna Formation could not be related to Jeju volcanic rocks, but possibly to pre-existing basement rocks. Thus, we propose that the Tamna Formation was formed from the materials derived from both pre-existing basement rocks and Jeju volcanic rocks, which were subsequently affected by diagenesis, hydrothermal alteration and weathering process.