• Economic and Environmental Geology
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• v.33 no.3
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• pp.229-237
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• 2000

The structure of Euiseong Sub-basin and boundary of sub-basins were examined by analytical aeromagentci anomaly data. Magnetic lineaments have trends of NE-SW, NWW-SEE and NEE-SWW. The NE-SW lineaments in the sedimentary formations and pre-Cretaceous basement are assoicated with the direction of expansion of basin and the lineaments in the volcanic rocks and intrusives indicate the direction of structural weakness ones such as fault, which were major gateways of igneous activities. Euiseong Subbasin is bounded by pre-existing Andong Fault, pre-Cretaceous basement in the west, NE-SW lineament from Jyungsan to Angang, and NW-SE lineament connecting southwestern boundary of Palgongsan Granite and Jeokje Fault. In particular , the NW-SE lineament , which caused upheavel of pre-Cretaceous rocks, on Jeokje Fault is inferred as a boundary between Euiseong and Milyang Sub-basins.

• Journal of the Speleological Society of Korea
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• v.20 no.21
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• pp.34-43
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• 1989

Cheju island is situated at about 60km south of southern most tip of the Korean peninsula. Its shape is an ellips with size of 80*40$\textrm{km}^2$, and it is characterized by a symmetrical form whose peak is Mt. Halla(1950m). Major chemical composition of the rock samples from Manjang gul cave is determined by XRF using the fundamental parameter method consisting of fully auto quantitative analysis, semi quantitative analysis (order estimation) and group quantitative analysis. Judging from chemical composition (SiO$_2$ = 53.07Wt％, Fe$_2$O$_3$ = 11.34Wt％, MgO=6.48Wt％, Na$_2$O=3.07Wt％, $K_2$O=1.05Wt％), this rocks from the Manjang gul cave are also determined. The discrepancy of K-Ar ages is found. They are 0.03 Ma and 0.42Ma, respectively. This paper describes some problems experienced in dating young volcanic rocks and then discusses chemical composition, X-ray fluorescence analysis and the age of the formation of a lava tunnel such as Manjang gul cave in cheju Island.

• The Journal of the Petrological Society of Korea
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• v.10 no.1
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• pp.1-12
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• 2001

A small of carbonate rocks and spatially-associated ultramafic rocks uniquely occur in the ulsan iron-serpentine mine of the sourtheastern Kyungsang basin. The study of field geology, core drilling data and stable isotope analysis suggest that the carbonate rocks are carbonatite formed from the melt reflecting intrusive natures. Based on this study, the geology of the Ulsan iron-serpentinite mining area consists of Cretaceous sedimentary, volcanic, granitic ultramafic and carbonate rocks in ascending order. The carbonate and ultramafic rocks show concentric and ellipsoidal shapes at the outcrop and a funnel shape in the cross sectional view. Carbon and oxygen stable isotope analysis show a bimodal pattern rather than a typical mantle pattern, which may indicate that the melt was a secondary melt generated within the crus not in the mantle directly. The uprising of ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crus. Then, the intrusion of the ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crust. Then, the intrusion of the ultramafic melt was followed by the intrusion of the carbonate melt along deep-seated fractures. Well-developed major fractures in this area, fluid inclusion characteristics of the carbonate rocks, the spatial relation between the ultramafic and carbonate rocks and stable isotope data support interpreting the Ulsan carbonate rocks as carbonatite.

• Proceedings of the KSEEG Conference
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• 2001.04a
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• pp.218-218
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• 2001

• Journal of the Korean Magnetics Society
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• v.20 no.3
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• pp.114-119
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• 2010

Fe compounds of volcanic rock samples distributed in the seaside area of Ulleung island were investigated by means of X-ray diffractometry (XRD), X-ray fluorescence spectroscopy (XRF) and M$\ddot{o}$ssbauer spectroscopy. We found that samples were typical basic rock which had the total amount of iron compounds including hematite ($\alpha-Fe_2O_3$) varies from 10.6 w% to 14.5 w% depending on the different regions by XRF. The M$\ddot{o}$ssbauer spectra of the samples were consisted of one sextet due to hemitite and doublets due to $Fe^{3+}$ in various clay mineral and $Fe^{2+}$ in pyroxene $(Ca,Fe,Mg)_2(SiO_4)_2$, ilmenite ($FeTiO_3$) and olivine $(Mg,Fe)_2SiO_4$. The balance state of Fe ions of all samples was chiefly $Fe^{3+}$, so we could find that the volcanic rocks distributed in the seaside area of Ulleung island were made in inland.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.27-35
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• 2015

This study aims to establish the age of the Cretaceous Togeum Formation in Gurye that reported the discovery of dinosaur eggshells and bones. This study also investigates to determine the period of the dinosaurs' dominance in the region. K-Ar ages are measured on the whole volcanic rocks in the lower - and upper parts of the formation. The six samples dated are volcanic pebbles deposited in the Geumjeongri Conglomerate that is distributed underneath the Togeum Formation, and the ages dated as Aptian ($118.3{\pm}2.3Ma$) or Albian ($103.6{\pm}2.0$, $102.5{\pm}2.0$, $99.9{\pm}1.9Ma$), which all correspond to the Early Cretaceous. In addition, the ages of andesites and porphyritic andesites overlying the Togeum Formation are dated in a similar way. The result is that the ages are apparently corresponding to the Campanian ($83.9{\pm}1.6$, $74.2{\pm}1.5$Ma) of the Late Cretaceous. Field evidence and the age results indicate that the formation of the Togeum and the activities of dinosaurs dated back between 84 and 100Ma. It suggests that the Togeum Formation be somewhat older than the Boseong Seonso Formation (81Ma) which contains egg shells, the Haenam Uhangni Formation (79-81 Ma) that has dinosaur, pterosaur and webbed bird footprints, and also older than the theropod egg nests (77-83Ma) found in the Aphaedo area.

• Explosives and Blasting
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• v.18 no.3
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• pp.99-106
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• 2000

The geology of Nogsan industrial estate area, Pusan, Korea consists mainly of andesitic rocks, rhyolitic rocks and hornblende granite. They are then intruded by basic and acidic dikes. All of the igneous activities in this area are in Cretaceous time, that is the lower part of Silla group in Gyoungsang basin. Andesitic volcanic rocks are distributed in two separate basines: Saengok basin and Doodong basin. Although both basines contain andesite and andesitic breccia(Kab), younger andesitic activity was more active to the western Doodong basin giving very little influence on the eastern Saengok basin. Sediments in the area are quarternaly alluvium and colluvium. Alluvium is very thick and consists mainly of silt and clay deposited as delta deposits at the mouth of Nakdong river. Colluvium in the area is short distributary channel deposits. The area is largely filled with socks and sediments to build industrial estates especially on the delta deposits at Shinhodong area and on the shoreline mud bed between Yongwondong and Shinhodong. A careful investigation to avoid the possibility of a large scale mud flow is suggested because it could be trigered by many reason such as an earthquake or a flood on the land where a heavily loaded salt-water may soaked into the muddy bed lying on the granitic basement gently dipping toward the ocean. Althouth the area is in the Yangsan fault zone no ground evidence of fault can be seen despite the RESTEC sattlite image gives excelent traces of linearments in the area.

• Journal of the Speleological Society of Korea
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• v.45 no.46
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• pp.9-31
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• 1996

The Mt. Peakdu is situated in north of the main peninsula, commanding geographically coordinated between longitude W($127^{\circ}$ 15' - $128^{\circ}$ 00') to E($128^{\circ}$ 15'- $129^{\circ}$ 00'), between latitude from S($41^{\circ}$ 15'- $42^{\circ}$ 00') to N($42^{\circ}$ 10'- $42^{\circ}$ 40'). The Manjyang-Gul in Cheju volcanic island is situated in the south of the main peninsula, commanding the Korean Strait, geographically coordinated longitude N($33^{\circ}$ 32' 26") and E($126^{\circ}$ 46' 48"). The quantitative analysis using XRF of volcanic rock samples for the north of Lu- Ming- Feng in Mt. Peakdu Group and the Manjang-Gul in Cheju island was Performed. The major chemical components by group analysis are as follows; Peakdu-Mt. Cheju Peakdu-Mt. Cheju (1) $Na_2O$(3.29Wt% and 3.27Wt%) (2) MgO (3.95Wt% and 6.l5Wt%) (3) $Al_2O_3$((17.64Wt% and 15.l7Wt%) (4) $SiO_2$((50.62Wt% and 50.99Wt%) (5) $P_2O_5$ (0.36Wt% and 0.30Wt%) (6) $K_2O$ (1.37Wt% and 1.04Wt%) (7) CaO (8.56Wt% and 8.06Wt%) (8) $TiO_2$ (2.37Wt% and 2.l5Wt%) (9) MnO (0.llWt% and 0.l6Wt%) (10) $Fe_2O_3$(9.l2Wt% and 12.56Wt%) The Group analysis data were compared in the relation within the age of formation for $0.16{\pm}0.08Ma$ in Mt. Peakdu Group, and $0.42{\pm}42Ma$ or $0.42{\pm}42Ma$ in Cheju island for K-Ar age. The crystal structure are mixed crystal of monoclinic, hexagonal and triclinic system in Mt. Peakdu Group and mixed structure of triclinic and cubic system in Cheju volcanic island.ic island.

• Economic and Environmental Geology
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• v.8 no.4
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• pp.183-201
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• 1975

The south and southwestern parts of Jeonra-namdo has been known as an alunite province in Korea. The alunite deposits investigated for the present study are Okmaisan, Seongsam, Bugog, Gasado south, Gasado north, Jangsando, Dogcheon and Jungyongri deposits. The main purpose of this study is to depict the genetical origin of the alunite deposits. The rocks distributed in the areas mentioned above consist chiefly of rhyolitic tuff, breccia tuff and andesitic tuff of Cretaceous age which represent different episodes of volcanic activities during Cretaceous epoch. The attitude of bedding of the tuffaceous rocks varies from place to place but generally dips very gently. The alunite deposits are embedded mostly in the rhyolitic tuff so that they appear as layered deposits, this occurrence may be the result of stratigraphic and lithologic controls. The result of this study can be summarized as below. The mineral sequence studied by the mineral paragenesis and the result of the spectrograph anlyses is such that (1) alunite was formed at first and pyrophyllite was nearly contemporaneous with alunite but pyrophyllite formation can be recognized as a secondary mineralization products, (2) kaoline was succeeded to form later and hematite finally deposited, and (3) pyrite was deposited from the begining to the end of the above mineralization period. The compositional change of host rocks is such that CaO, $SiO_2$ and $Na_2O$ were largely removed from the parent rocks and some $Al_2O_3$ and $SO_3$ were transported by the solution so as to enrich the rocks. The sequencial process of such mineralization has resulted in forming those distinguish mineral zones; alunite, kaoline, pyrophyllite, silicifide and sulphide zone which manifest irregular shape. These deposits were formed by hydrothermal solution which was possibly low temperature and contained sulphuric acid originated from $H_2S$ and $SO_2$ gases.

• The Journal of the Petrological Society of Korea
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• v.20 no.1
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• pp.1-21
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• 2011

Eoil basalt in the Eoil basin and Yeonil basalt and its related volcanic rocks in Guryongpo and Daebo area were researched and analyzed to purse the tectonic settings and magma characteristics of those Tertiary volcanic rocks in the south-east Korean peninsula. It is highly suggested that zoning, resorption and sieve texture in plagioclase and reaction rim in pyroxene indicate unstable tectonic environments and complex volcanism in the study area. Volcanic rocks from Janggi basin are identified as basalt and basaltic andesite in TAS diagram and sub-alkaline series in terms of magma differentiation. $Na_2O$ and $K_2O$ show positive trend however FeO, CaO, MgO and $P_2O_5$ indicate negative trend in Harker variation diagram with $SiO_2$. Basaltic rocks from Eoil area are identified as calc-alkaline series in AFM diagram and show medium K series calc-alkaline in $K_2O-SiO_2$ diagram. Compatible trace elements of Co, Ni, V, Zn, and Sc in Yeonil basalt show negative trend with crystallization but incompatible trace element of Ba, Rb show positive trend with $SiO_2$ 0.81~1.00 of $Eu/Eu^*$ value suggests minor effect of plagioclase fractionation in Yeonil basaltic rocks. Plagioclase composition of Eoil basalt ranges from $An_{63.46-98.38}\;Ab_{1.62-32.96}\;Or_{0-3.58}$ (anorthite-labradorite) in core to $An_{40.89-82.44}\;Ab_{17.10-46.43}\;Or_{0-12.68}$ (bytownite-labradorite) in rim. $^{87}Sr/^{86}Sr$ and 143Nd;t44Nd ranges 0.704090~0.704717 and 0.512705~0.512822 respectively. Negative linear trends in 87Sr/86Sr and $^{143}Nd/^{144}Nd$ correlation diagram indicate that magma produced Yeonil basalt and basaltic andesite has been originated as partial melting product of mantle wedge by subducting Pacific plate affected by oceanic crust with less effect of continental crust indicating calc-alkaline magma characteristics.