• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.363-381
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• 2006

Mineral compositions of granitic rocks from Geochang, Pocheon, Iksan, and China were obtained by the modal analysis, CIPW norm calculations, and Rietveld quantitative analysis for stone specification of the Geochang granitic rocks. The Geochang granitic rocks show grey to dark in color and medium grained porphyritic texture. They mainly consist of quartz, plagioclase, alkali feldspar, and biotite. Among three different method for determining the mineral compositions of granitic rocks, normative compositions using X-ray fluorescence data are not appropriate for representing real mineral composition. Rietveld quantitative analysis using X-ray powder diffraction data is proved better method to determine exact mineral compositions than modal analysis using microscopic observation. Q-A-P diagram shows that the Geochang granitic rocks are typical granodiorite, whereas the granitic rocks of Pocheon, Iksan, and China are monzogranite, monzogranite to granodiorite, and granodiorite, respectively. Compared to China ones, the Geochang granitic rocks are nearly close to each other in mineral composition.

• Economic and Environmental Geology
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• v.33 no.2
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• pp.147-163
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• 2000

The Buseok pluton in the Yeongju Batholith is a comagmatic plutonic rocks which haveconcentrically compositional zoning. The lithofacies of the Buseok pluton comprise hornblende biotite tonalite in the southern part of the pluton, porphyritic and equigranular biotite granodiorite in the northern part and biotite granite in the north-central part. The compositional variations change gradually with continuity both within and between the lithofacies. The concentrically zoned pattern is relatively mafic rocks composed of high-temperature mineral assemblages in margin of the southern part, passing inward and northward gradually to more felsic rock in core of the north-central part. Changes in the textures and microstructures, as well as in the mineral content, take place between rock types of the plutons. Darker colored, generally coarse-grained, well foliated tonalite pass inward to light colored, coarse-grained, poorly foliated granodiorite, and finally give way to lighter colored, medium-grained, nearly nonfoliated granite. The foliation are best developed in the marginal part of the tonalite. Here, the regional myolitic foliation in the tonalite is steep northward and parallels to its southeastern contact with the country rock, but the magmatic foliation from disc-shaped mafic microgranitoid enclaves is subvertical and parallels the contacts with the country rock. As the tonalite approaches biotite granite in composition, the foliation is indistinct. Modal and chemical data for the pluton show quantitative compositional variation from the margin of the southern part to the core of the north-central part. Quartz and K-feldspar increase toward the core of the pluton, whereas hornblende, biotite and color index decrease. /Abundances of $SiO_2$and $K_2O$$_2$O increase toward the core according to the variation in quartz and K-feldspar, whereas those of MnO, CaO, $TiO_2$, $Fe_2O_3$, MgO and $P_2O_5$ decrease corresponding to the variation in mafic and accessaries. The compositional zonation resulted from fractional crystallization involving downward settling of earlier crystals, accompanied by upward movement of melt and volatiles, and followed by accessary marginal accretion of crystalline material in the magma to the marginal part. Although a little crustal contamination by the wall rock is recognized from the isotope data, the contamination is not only dominated over but also appropriate for forming the compositional variation in the pluton.

• Journal of the Mineralogical Society of Korea
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• v.18 no.3 s.45
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• pp.165-181
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• 2005

The granitic rocks distributed in the southern part of the Yangsan Fault are classified into five distinct rock facies based on the field relation, petrography and geochemical characteristics. These five different rock facies can be grouped into two considering their origins. Group I, which reveals various evidences of magma mixing, includes three rock facies of granodiorite, enclave-rich porphyritic granite, and enclave-poor porphyritic granite. Group H intruding Croup I includes equigranular granite and micrographic granite with no evidence of magma mixing. It is suggested that the distinctively different trace element and isotopic chemistries between group I and II, support evolution from the different parental magma. It is suggested that the three rock facies in group I were generated by different degrees of magma mixing in addition to fractionation of plagioclase. MMEs experienced fractionation of biotite. The two facies in group H seem to have been generated from different parent magma from group I and evolved by fractionation of K-feldspar. The Rb-Sr whole-rock ages of the group I rocks yield $59.2\~58.9Ma$, and those of the group II rocks give 53. $3\~51.7Ma$, regardless of their distribution whether they occur in the eastern or western parts of the Yangsan Fault. Based on Sm-Nd isotope compositions, depleted mantle model ages $(T_2DM)$ of the group I range $0.8\~0.9Ga$, while those of the group II$0.6\~0.7Ga$.

• The Journal of the Petrological Society of Korea
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• v.15 no.1 s.43
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• pp.39-48
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• 2006

U-Pb ages were determined from the granitic rocks from central and northeastern parts of Yeongnam massif. Porphyritic granite of Seosang-myeon, Hamyang-gun near the boundary with Anui-myeon shows age of $225.4{\pm}4.1Ma$. Foliated granodiorites of Anui-myeon, Hamyang-gun and Sinwon-myeon, Geochang-gun are $195.6{\pm}1.8Ma$ and $194.2{\pm}2.4Ma$ old respectively. Granites from Hari-myeon and Buksang-myeon of Geochang-gun show almost identical ages of $198.4{\pm}2.5Ma$ and $194.6{\pm}2.6Ma$ respectively, while foliated granodiorite of Yeongju shows an age ot $171.3{\pm}2.3Ma$. Combining with previously reported results, Triassic granitoids were emplaced almost identically at ca. 225 Ma throughout the areas of Hamyang and Sangju oi Yeongnam massif and Baengnok, Jeomchon and Goesan of Okcheon metamorphic belt. There were significant gap of non-magmatism before the resume of granitic activities over the large areas of Hamyang-gun, Geochang-gun, Gimcheon-si and Seongju-gun from Triassic-Jurassic boundary to early Jurassic, 200-194 Ma. Igneous activity within the Yeongnam massif of this period has not been reported from the Okcheon belt or Gyeonggi massif and may reflect distinct tectonic environment. Around 170 Ma, when Yeongju granodiorite was emplaced, there were active granitic magamtism throughout the Yeongnam massif, Okcheon belt and also Gyeonggi massif.

• Economic and Environmental Geology
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• v.11 no.2
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• pp.47-57
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• 1978

The study focused on the petrology and petrochemistry of the so called "Ganghwa syenitic rocks" which intruded into metasediment of basement in southeastern part of Ganghwa Island. The geologic sequence of the mapped area was shown in table 1, 10 model analyses and 7 chemical analyses on the rock samples taken from the Ganghwa syenitic rocks and Manisan granite have been used to discuss the nomenclature of the rocks and petrological relationship between rock types. The petrograpical and petrochemical features based on, the analyses are as follows: 1) Ganghwa syenitic rocks consist of Ganghwa alkali syenite and Ganghwa diorite porphyry which based on the classification of the subcommision on systematics of igneous of IGUS. Ganghwa diorite porphyry which occured as dike forms are intruded into Ganghwa alkali syenite. The rock forming minerals of Ganghwa alkali syenite are composed of perthite, plagioclase, quartz, hornblend and chlorite in major, and zircon, apatite, sericite and magnetite in minor. Ganghwa diorite porphyries consist of plagioclase, biotite, hornblend, orthoclase and chlorite, with, porphyritic texture. 2) In silica-oxides variation (Fig. 2) and AMF diagram (Fig_ 3), the Ganghwa alkali syenite is similar to the trend of Daly's average basalt-andesite-dacite-rhyolite than Skaergaard which shows the trend of the fractional crystallization of magma, and equivalent to the alkali rock series by Peacock. 3) The general trend of data points shift to plagioclase, and are superimposed on the alkali rich terminal part of the granodiorite province of SW Finland in normative Q-Kf-Pl(Fig. 4) and Or-Ab-An diagram respectively. The above-mentioned evidences suggested that the Ganghwa syenitic rocks are the differential products resulted by assimilation of intermediated magma and metasedment rock under relatively rapid cooling condition.

• Economic and Environmental Geology
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• v.18 no.4
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• pp.381-397
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• 1985

A petrological study has been done in the pyeongchang-Jaecheon area which is a northwestern part of the basement of Ogcheon zone for the purpose of comparison of the area to the Nogjeon-Yeongchun area which is the antipodal basement of the zone in the petrological and geotectonical view points. The major units of the area are Precambrian granitic gneissic complex, banded gneiss, linea ted leucocratic gneiss and pegmatitic leucogranitic gneiss in the west, elongated exposure of quartz schist (or partly quartzite) and phyllite, named as Jungdaegal-bong Group correlated to the lower sequence of Joseon Group, in the middle, and limestone and calcic dolomite, Iptanri Formation, correlated to the middle of Joseon Group in the east. Igneous plutons are distributed in the areas of gneissic complex and limestone formation as well as in the Eosangcheon and Daedaeri areas in the southeastern out of the area. Present study reveals that the gneissic complex are the products of granitization to metamorphism of amphibolite facies in the order of above mentioned from the metasediments of schists and calcareous rocks. A notable characteristics of the phyllite of Jungdaegal-bong Group is the presence of syntectonically segregated quartz rods in the forms of lens, swirl or boudinage in evenly distributed in the phyllitic to chloritic matrix. Igneous rocks range in composition from gabbro through diorite, granodiorite, to schistosed and porphyritic granites in stock and dike. The orogenic movement of the Ogcheon zone initiated in the middle Proterozoic time, pre-sedimentation of Ogcheon Group and superposed the granitization in Permian, Jurassic Daebo orogeny with granitic batholiths and stocks, and Cretaceous plutonic intrusion.

• Economic and Environmental Geology
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• v.20 no.3
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• pp.203-209
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• 1987

The gravity measurement has been conducted at 69 points with an interval of about 1km along the national road between Masan and Busan through Kimhae to study on the subsurface geology and structure of Kyongsang basin. The Bouguer gravity anomalies were obtained from the observed gravity values, and interpreted by means of the Fourier-series method and Talwani method for 2-dimensional body. The depth of Conrad discontinuity is about 14.8km at the west end of survey line, and increases smoothly to about 13.6km at the east end. But it is uplifted by about 500m between Yangsan and Dongnae faults. The depth of the basement of Kyongsang basin is about 4.8km at the west end. It decreases gradually passing Masan, and reaches the maximum depth of 5.6km at the 15km east of Masan. Hereafter, it starts to increase to 4.3km at the east end. It is also uplifted by about 500m between Yangsan and Dongnae faults. The Bulgugsa granites which cause two low Bouguer gravity anomaly zones are distributed in the vicinity of Masan at depth of about 3.5km and Kimhae area at depth of about 5.3km. Diorite, granodiorite, aplite, and felsite are distributed with various depth of about 1~1.7km, and Jusasan andesitic rocks, except porphyritic one located at the west of Kimhae, are distributed with depth of about 1km. Three fracture zones associated with faults are located at the places where v-shaped Bouguer gravity anomalies are appeared.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.675-687
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• 2005

The rocks of the five storied stone pagoda in the Jeongrimsaji temple site are 149 materials in total with porphyritic biotite granodiorite. They include pegmatite veinlet, basic xenolith and evenly developed plagioclase porphyry. This stone pagoda has comparably small fracture and cracks which are farmed in the times of rock properties, but surface exfoliation and granular decomposition are in process actively since the rocks are generally weakened from the influence of air contaminants and acid rain. Structural instability of constituting rocks in the 4th roof materials are observed to occur from distortion and tilt. Such instability is judged to threat stability of the upper part of the stone pagoda. Also, chemical weathering is operating even more as the contaminants, ferro-manganese hydroxides eluted from water-rock interaction on the rock surface. Most of the rock surface is covered with yellowish brown, dark black and light gray contaminants, and especially occur in the lower part of the roof rocks on each floor. The roof underpinning rocks are severe in surface pigmentation from manganese hydroxides and light gray contaminants. The surface of rocks lives bacteria. algae, lichen, or moss and diverse productions in colors of light gray, dark Bray and dark green. Grayish white crustose lichen grows thick on the surface with darkly discolored by fungi and algae in the first stage on basement rocks, and weeds grows wild on the upper part of each roof rocks. This stone pagoda must closely observe the movements of the upper part rock materials through minute safety diagnosis and long term monitoring for structural stability. Especially since the surface discoloration of rocks and pigmentation of secondary contaminants are severe, establishment of general restoration and scientific conservation treatment are necessary through more detailed study for this stone pagoda.

• Economic and Environmental Geology
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• v.37 no.5
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• pp.569-583
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• 2004

The rock properties of the West pagoda in the Gameunsaji temple site are composed mainly of dark grey porphyritic granodiorite with medium grained equigranular texture and developed with small numerous dioritic xenoliths. These xenoliths occurred with small holes due to different weathering processes. As a weathering results, the rock properties of this pagoda occur wholly softened to physical hardness because of a complex result of petrological, meteorological and biological causes. Southeastern part of the pagoda deteriorated seriously that the surface of rock blocks showed partially exfoliations, fractures, open cavities in course of granular decomposition of minerals, sea water spray and crystallization of salt from the eastern coast. The Joint between blocks has small or large fracture cross each other, contaminated and corrupted for inserting with concrete, cement mortar, rock fragments and iron plates, and partially accelerated coloration and fractures. There are serious contamination materials of algae, fungus, lichen and bryophytes on the margin and the surface on the roof stone of the pagoda, so it'll require conservation treatment biochemically for releasing vegetation inhabiting on the surface and the discontinuous plane of the blocks because of adding the weathering activity of stones and growing weeds naturally by soil processing on the fissure zone. Consisting rock for the conservation and restoration of the pagoda would be careful choice of new rock properties and epoxy to reinforce for the deterioration surfaces. For the attenuation of secondary contamination and surface humidity, the possible conservation treatments are needed.

• Economic and Environmental Geology
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• v.45 no.5
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• pp.535-549
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• 2012

Main aspect of this study are to clarify mineral compositions on granites in Youngkwang-Naju area. These granites are is divided into four rock facies based on the geologic ages, mineralogical composition and chemical constituents, and texture : hornblende-biotite granodiorite, biotite granite, porphyritic granite and two mica granite. These granites constitude an igneous complex formed by a series of differentiation from cogenetic magma. In compressive stress field between the Ogcheon folded belt and the Youngnam massif, the foliated and undeformed granites had formed owing to heterogeneous distribution of stress. The geochemical data of study area indicate magma of these rocks would had been generated by melting in lower and middle crust. The major minerals of granitic rocks in study area are plagioclase, biotite, muscovite and hornblende. Plagioclase range in composition from oligoclase ($An_{19.3-27.7}$) to andesine ($An_{28.4-31}$), and shows normal zoning patterns, This uniformed composition indicated slow crystallization, and it is obvious that the growth of these crystal occurred before final consolidation of the magma. The Mg content of biotite are increases with increasing of $f_{O2}$ and grade of differentiation, changing from phlogopite to siderophyllite. Its $Al^{iv}$/$Al^{total}$ ratios are propertional to bulk rock alumina content. Muscovite is primary in origin with high content of $TiO_2$, and Its composition correspond to celadonitic muscovite. Hornblende indicated calc amphibole group ($(Ca+Na)_{M4}{\geq}1.43$, $Na_{M4}<0.67$). and consolidation pressure of granitic body by geobarometer of Hammerstrume and Zen show 11.3~17.2 Km.