• The Journal of the Petrological Society of Korea
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• v.27 no.3
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• pp.121-138
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• 2018

We have examined the petrotectonic setting and magmatic evolution from petrochemical characteristics of major and trace elements for the Cretaceous volcanic rocks in and around the Mireukdo Island. The volcanic rocks, can be devided into Jusasan, Unmunsa, Yokji and Saryang subgroups on the ascending order, are classified as basalt, basaltic andesite, andesite, dacite and rhyolite on TAS diagram. Petrochemical data show that the rocks are calc-alkaline series, and suggest that erupted earlier medium-K series and later high-K series. The volcanic rocks provide a case in which the calc-alkaline magma are formed, not only from separate protoliths, but following separate paths from source to surface. Earlier and later subgroups take different paths to the surface respectively, and are emplaced in the shallow crust as a series of discrete magma chambers through the volcanic processes. After emplacement, each chamber evolves indepently through fractional crystallization with a little assimilation of wall rock. The volcanic rocks have close petrotectonic affinities with orogenic suite and subduction-related volcanic arc. The rhyolitic magma can be derived from calc-alkaline andesitic magma by fractional crystallization with crustal assimilation, which may be derived from a partial melt of peridotite in the upper mantle.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.565-568
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• 2008

This study area, Sanbang mountain located in southern part of Jeju island, is famous for its scenic with increasing foreigners and visitors. However, rockfall frequently occurred because of the meteorological characteristic and geological features with trachyte, a sort of volcanic rock, is distributed through Sanbang mountain area and also additional rockfalls are being existed all the time. Therefore this research is to see reasonable countermeasure against rockfall with the subject of a roundabout way of Sanbang mountain, through field investigation and following analysis.

• Journal of the Korean earth science society
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• v.32 no.3
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• pp.265-275
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• 2011

The Hamo and Hyeopjae beaches in the western part of Jeju Island were studied in terms of seasonal variations of surface sediment and beach profile. Seasonal drift direction of the beach sands also was investigated. The Hamo beach of $7.3^{\circ}-10.8^{\circ}$ steep is composed of medium sand containing volcanic clasts and shell fragments. The Hyeopjae beach of $2.8^{\circ}-6.5^{\circ}$ steep is composed of coarse shelly sand. Hamo beach deformation is probably caused by the jetties constructed in the western part of the beach. In the Hyeopjae beach, surface sands were drifted into the dune side by the northwestern stormy wind during winter season.

• Economic and Environmental Geology
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• v.18 no.1
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• pp.55-63
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• 1985

Studies based on field observation and laboratory analysis of the littoral sands of beaches in Jeju Island indicate that the shores exhibit a great variation in both the beach geometry and the composition in terms of geological agents. Most of the beaches around the Island are developed in relatively small patches and discontinuous, as the result of intervening sea cliffs and rocky headlands. The sand quality and the dimensions of the beaches in the Island are relatively poor; for example, these beaches are 220~2,780m in length, 41~313m in width, and $7^{\circ}$ steepness in average foreshore slope. According to the textural parameters analysis, the beach sediments in study portion shows medium grained ($average\;1.42{\phi}$), moderately well sorted ($average\;0.65{\phi}$) and negative skewed ($average\;0.34{\phi}$), which seems to reflecting a high energy marine depositional environment. The heavy and light minerals of te beach sediments are composed of quartz, volcanic fragments, Na-Ca feldspar, olivine, augite as major constituents, along with apatite, biotite and other minor components, which originates from the adjacent geology. The content of CaO-MgO in shell fragments of the littoral sands ranged from 4.69~51.96%, suggesting that the high CaO-MgO content in some of the Island's beaches is attributable to geologic environments conducive to the growth of shell organisms and sediments migration. The provenance of the sediments studied are derived predominantly from adjacent continental shelves and/or terrigenous older river portion, Which sediments were transported mostly by rolling or bottom suspension. The depositional environments of the Jeju beaches can be divided into two types: beaches distributed in the North and the Northeastern parts of the Island are dominated by marine enviroment, whereas beaches in the Southwestern portion are characterized by terrigenous agencies.

• Journal of the Korean Magnetics Society
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• v.12 no.1
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• pp.7-13
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• 2002

The studies of non-figure plain coarse pottery from Jeju island is very important because it can explain the characters of plain coarse potteries of the bronze age and the early iron age. In this study, We analyzed the non-figure plain coarse popery from Jeju island in two ways. One is analysis of the chemical composition using X-ray fluorescence spectrometer and X-ray diffraction, the other is analysts of clay mineral contained iron, oxidized iron's genus, valence state and magnetic properties using Mossbauer spectroscopy. We confidence that non-figure plain coarse pottery is chiefly made of silicate minerals, like SiO$_2$. The content of noncrystalline ferrihydrite is supposed to be below 5-10 wt%, non-figure plain coarse pottery is considered to partly consist of Jeju island clay, which is made of neutral volcanic rock and the valence state of iron is Fe$\^$2+/ and Fe$\^$3+/. We presume the reason that the magnetic hyperfine field is lower than that of pure goethite is the change of crystal structure which transforms the combination states of Fe ions while the clay is being fired.

• Journal of the Korean earth science society
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• v.24 no.4
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• pp.337-345
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• 2003

Surficial sediments from the northern coastal area of Jeju Island, southeastern Yellow Sea (South Sea of Korea) were analyzed for grain-size texture, some geochemical characteristics and clay mineralogy in order to assess their provenance. Rare-earth element compositions and some geochemical discrimination diagrams, especially of Ti/Al, Nb/Al and Rb/Al ratios, were revealed to be useful indices for identifying the origin of sediments. These indices, together with clay mineral compositions, suggest that the coarse-grained sediments originate from the volcanic rocks of Jeju Island, whereas the fine-grained sediments are derived from Chinese rivers, especially the Changjiang River. The oceanic circulation pattern and the physical-chemical properties of seawater in the Yellow and East China seal support the possibility that the fine-pained Changjiang (Yangtze River) sediments can reach the coastal area of Jeju Island (southeastern Yellow Sea).

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1563-1573
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• 2016

The aim of this study was to evaluate the occurrence of vanadium in Jeju Island groundwater, focusing on the spatio-temporal patterns and geochemical controlling factors of vanadium. For this, we collected two sets of groundwater data: 1) concentrations of major constituents of 2,595 groundwater samples between 2008 and 2014 and 2) 258 groundwater samples between December 2006 and June 2008. The concentrations of groundwater vanadium were in the range of $0.2{\sim}71.0{\mu}g/L$ (average, $12.0{\mu}g/L$) and showed local enrichments without temporal/seasonal variation. This indicated that vanadium distribution was controlled by 1) the geochemical/mineralogical composition and dissolution processes of original materials (i.e., volcanic rock) and 2) the flow and chemical properties of groundwater. Vanadium concentration was significantly positively correlated with that of major ions ($Cl^-$, $Na^+$, and $K^+$) and trace metals (As, Cr, and Al), and with pH, but was negatively correlated with $NO_3-N$ concentration. The high concentrations of vanadium (>$15{\mu}g/L$) occurred in typically alkaline groundwater with high pH (${\geq}8.0$), indicating that a higher degree of water-rock interaction resulted in vanadium enrichment. Thus, higher concentrations of vanadium occurred in groundwater of $Na-Ca-HCO_3$, $Na-Mg-HCO_3$ and $Na-HCO_3$ types and were remarkably lower in groundwater of $Na-Ca-NO_3$(Cl) type that represented the influences from anthropogenic pollution.

• Economic and Environmental Geology
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• v.19 no.1
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• pp.25-33
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• 1986

The geology of the Jeju island is characterized by the occurrence of thick voluminous basaltic lava flows and minor trachytic lavas. The land form can be divided topographically into the lava plateau, the shield-shaped Halla volcanic edifice and the parasitic cones whose number is more than 360, which is closely related to the cyclic volcanism of the island. Especially, the trachytic lavas seem to be the latest differentiation products of the cyclic activities and largely classified into two groups (Backlokdam group and Sanbangsan group) on the basis of the occurrence and the petrography. The paleomagnetism and the radiometric age on the two groups of trachyte suggest a lower and an upper time limits of the volcanic stratigraphy of the island. An average age of the trachyte of the Sanbangsan group is $0.733{\pm}0.056m.y.$, and is correlated to a horizon a little lower than the boundary (0.69m.y.) between the Brunches normal epoch and Matuyama reversed epoch. An average age of $0.025{\pm}0.008m.y.$ determined from the Backlokdam trachyte may be corrected to anyone horizon of the Laschamp, or the Lake Biwa, or the Lake Mono excursion. The two groups of trachytes are distributed with the latitude difference of 9'($0.15^{\circ}$), and with age difference of about 0.71 m.y. Assuming that the two trachyte groups were erupted from the same stationary hot spot, the lithosphere comprising the Jeju island is considered to have moved southward with a rate of about 2.3 cm/year.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.141-150
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• 2010

Basaltic ash of Udo tuff cone, Jeju Island, was almost fresh across strata, but significantly altered toward surface by supergene process. The supergene alteration of the Udo tuff was examined by using X-ray diffraction, scanning and transmission electron microscopy, and electron microprobe analysis for elucidating the alteration process of basaltic ash in terrestrial environments. Fresh ash particles were composed of glass matrix, plagioclase, olivine, and pyroxene. The glass matrix was selectively replaced inward by colloform alteration rinds of Fe-Ti-rich amorphous silicate nanogranules and smectite, often leaving glass core at the center of larger ash particles. Some of the dissolved species released from the altered ash particle precipitated as fine honycomb aggregates of smectite on the pore walls, contributing to the cementation and lithification of volcanic ash.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.65-69
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• 2009

We studied to compare the fractionation patterns of Ni, Cu, Zn in Jeju volcanic ash soils and to elucidate the uptakes of them by Pakchoi(Brassica campestris var. chinensis). Fractionation patterns of soils by sequential extraction method were different and make to distinguish from various soil types. In Pakchoi, the transfer rates of Ni, Cu, Zn from root to shoot were also different by metal types. There are low corelation between fractional contents in soil and contents in plants of trace elements except for exchangeable Zn. It is needed to develop novel methods for the assessment soil Ni in relation to plant uptake because of poor corelation.