• Journal of the Korean earth science society
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• v.18 no.6
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• pp.500-514
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• 1997

With respect to the amphibolites in the Mungyong area of the central part of the Ogcheon Fold Belt, detail field occurrence, texture and geochemical properties within each sills and petrogenetic environment are presented. We confirmed that the amphibolites in the Sangnaeri Formation (Ogcheon Supergroup) and limestone(Cambro-Ordovician Chosun Supergroup) sequences are metamorphosed dolerite sills which are roughly concordant to bedding of country rocks. Geologic distribution of the rocks is distinctly improved compared with those of previous investigations. There are four main sills so far observed in the study area. One is emplaced in limestone(Ls Sill, about 3 m thick) and the others are emplaced in Sangnaeri Formation, which are named First Sill(about 40 m thick), Second Sill(about 100 m thick) and Third Sill(about 40 m thick) from lower to upper horizons of the meta-pelitic sequences. The thick sills are intruded by minor sills and the Third Sill is a composite sill consisting of two main and two minor sills. Each sill has fine grained chilled marginal zones and grain size increases inwards from both contacts. The Second Sill has various vein and white patch in central part and the rock compositions vary systematically from margin to central part. $SiO_2,\;Na_2O,\;K_2O\;and\;P_2O_5$ increase, whereas $TiO_2,\;FeO,\;Al_2O_3\;and\;CaO$ decrease toward the contort. We investigate the major and trace element variations of ten selected rock compositions as intruding initial magma take occurrence and chemical properties into consideration. The compositional variations of them can not be explained by fractionation crystallization of single magma. Geologic distribution, geochemical properties and previous data suggest that amphibolite precursors(basaltic magma) of the study area were intrusive as sill-like in an intracontinental rift environment.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.403-412
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• 2009

The objective of this study is to investigate the geochemical change of feldspar minerals by supercritical $CO_2$, which exists at $CO_2$ sequestration sites. High pressurized cell system (100 bar and $50^{\circ}C$) was designed to create supercritical $CO_2$ in the cell and the surface change and the dissolution of plagioclase and orthoclase were observed when the mineral surface reacted with supercritical $CO_2$ and water (or without water) for 30 days. The polished slab surface of feldspar was contacted with supercritical $CO_2$ and an artificial brine water (pH 8) in the experiments. The experiments for the reaction of feldspar with only supercritical $CO_2$ (without brine water) were also conducted. Results from the first experiment showed that the average roughness value of the plagioclase surface was 0.118 nm before the reaction, but it considerably increased to 2.493 nm after 30 days. For the orthoclase, the average roughness increased from 0.246 nm to 1.916 nm, suggesting that the dissolution of feldspar occurs in active when the feldspars contact with supercritical $CO_2$ and brine water at $CO_2$ sequestration site. The dissolution of $Ca^{2+}$ and $Na^+$ from the plagioclase occurred and a certain part of them precipitated inside of the high pressurized cell as the form of amorphous silicate mineral. For the orthoclase, $Al^{3+}$, $K^+$, and $Si^{+4}$ were dissolved in order and the kaolinite was precipitated. In the experiments without water, the change of the average roughness value and the dissolution of feldspar scarcely occurred, suggesting that the geochemical reaction of feldspars contacted with supercritical $CO_2$ at the environment without the brine water is not active.

• Economic and Environmental Geology
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• v.34 no.2
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• pp.227-241
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• 2001

Several $Co_2$-rich springs in the Chungcheong area, Le., the Angsung spring, the Chojung spring, the Myungam spring, the Bukang spring and the Daepyung spring have been long known for their particular water chemistry. The occurrences of these springs are closely related to the geologic structure of Mesozoic granite such as dyke swarms, fault zones and the geologic boundary between granite and its adjacent gneiss. The $Co_2$-rich water samples show a high $Co_2$ concentration ($P_{CO2}$ 0.25 atm to 0.99 atm), weak acidic pHs and the electrical conductivity ranging from 101 to 2,950 ${\mu}$S/cm. The $Co_2$-rich water samples are classified into the Ca-$HC0_3$ type and the Ca(Na)-$HCO_3$) type in chemical composition. Environmental isotopic data $^{2}H/^{1}H, ^{18}O/^{16}O$) indicated that $Co_2$-rich water was meteoric origin. The ${\delta}^{13}C$ values of $Co_2$-rich water range from -3.1$\textperthousand$ to -6.8$\textperthousand$ PDB. The values indicate that $H_2CO_3^0$ and $HC0_3^-$ of the water samples are mainly originated from a deep-seated source and partly contributed from carbonatc minerals. The major minerals determining the chemistry of $Co_2$-rich watcr arc probably the carbonate minerals which are present as veins and secondary minerals, and the plagiocalse in granite and gneiss.

• The Korean Journal of Petroleum Geology
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• v.12 no.1
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• pp.20-26
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• 2006

Late Quaternary stratigraphy and sedimentary environmental changes were studied based on four core sediments and their pore water taken from the southwestern part of the East Sea. The results of tephrostratigraphy and radiocarbon dates indicate that the cores cover the time interval from the middle stage of Marine Isotope Stage (MIS) 3 to MIS 1 (Holocene). The average of sedimentation rate in core sediments varies from 10 cm/kyr to 20 cm/kyr, but it fluctuates generally in particular time intervals such as MIS 2, which would be related with the sea-level changes at that time. On the other hand, the relations between ${\delta}^{13}C_{org}$ and C/N ratios suggest that the organic matter in the cores was originated mainly from marine algae. In addition, the value of ${\delta}^{13}C_{CH4}$ indicates bacterial origin rather than thermogenic one.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.56-68
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• 2005

We measured nitrate and other nutrients in sediment pore waters retrieved from three sites at the southern upper-tidal flats of the Ganghwa Island. Denitrification rate is estimated by applying a simple 1-D model to the nitrate profiles. Results from Jangwha and Dongmak sites are $7.8{\sim}9.4{\times}10^{-7}{\mu}mol{\cdot}cm^{-2}{\cdot}sec^{-1}$, and $1.4{\sim}3.6{\times}10^{-7}{\mu}mol{\cdot}cm^{-2}{\cdot}sec^{-1}$, respectively. Rates are comparable to those reported around the world in an order of magnitude. Denitrification was lower in summer. The rates were about 1.5 times higher at site where the surface sediments consist of relatively coarser particles. This implies that particle size would control the reactant supply to the subsurface sediment. One may claim the denitrification as an evidence of the biogeochemical purification function of tidal flat. However, the purification seems not a general attribute of a tidal flat when whole system is scrutinized by a thermodynamic criterion. Currently the term 'tidal flat' is used when describing the diverse coastal wetlands such as salt marshes, sandy tidal flats and muddy tidal flats, which exhibit quite different ecological functions. Thus it is worthy of mentioning that the classification of coastal wetlands on the basis of sedimentological characteristics and biogeochemical functions should facilitate our understanding.

• 한국석유지질학회:학술대회논문집
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• 2005.09a
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• pp.94-100
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• 2005

동해 울릉분지 북서부해역에서 채취한 코어퇴적물을 이용하여 울릉분지의 제4기 후기 층서와 퇴적환경을 연구하였다. 이를 위하여 테프라층서, 탄소연대측정, 퇴적상, 퇴적물의 암질, 퇴적물과 공극수의 원소성분 등을 분석하였다. 퇴적상을 기준으로 코어퇴적물은 Unit 1, Unit II 및 Unit III으로 나누어지며, Unit의 경계부근에서는 주로 화산력으로 구성된 2매의 향암질 또는 조면암질 테프라층과 주로 화산재로 구성된 1매의 유문암질 테프라층이 협재되어 나타난다. 이들 테프라층에는 울릉도에서 기원한 울릉-오키층(Unit I/II 경계, 약 8.1 cal. kyr BC)과 울릉-야마토층(약 30.7 cal. kyr BC), 일본에서 기원한 아이라-탄자와층(Unit I/II경계, 약 22.8 cal. kyr BC)이 있다. Unit II의 중간부근에서 발견되는 DLM(Dark Laminated Mud) 층에는 망간보다는 철이 상대적으로 풍부하고, 철은 주로 구상집적체의 황화철로 발견되는데, 이들 광물은 정체환경 동안 물의 순환이 약화된 시기에 무산소환경에서 형성되었다. 퇴적물 내 유기물은 해양성 기원으로, 열적 성숙단계가 대부분 미성숙단계에 놓여 있다. Termination I 전에 급격하게 총유기탄소 (TOC)의 함량이 증가함을 보여주는데, 이는 빙기에서 간빙기로 변하는 시기에 해수면 변동과 관련이 있는 것으로 보인다. 공극수와 공기층 가스의 분석에 의하면, 황산염($SO_4^{2-}$) 농도는 매몰심도와 함께 증가하고, 반대로 공기층 가스의 주성분인 메탄($CH_4$)의 농도는 감소한다. 이는 미생물학적인 활동과 관련된 황산염 환원작용이 코어 상부에서 일어났으며, 점차 메탄생성단계 (methanogenesis)로 전이가 일어났음을 의미한다.측해본 결과 침몰선체의 강도는 초기강도에 비해 약 2/5정도 감소하였음을 알 수 있었다.할 수 있었다. 이 연구 사례를 통하여 3차원 GPR 탐사 또한 국부적인 이상대의 규명뿐만 아니라 광역적인 고고학 조사에도 다른 물리탐사와 마찬가지로 쉽게 활용될 수 있다는 결론을 얻을 수 있었다. 3차원 GPR 탐사가 향후 국내의 문화재 조사에 표준화된 탐사과정 중의 하나로써 적극 활용되길 기대한다.larity가 높은 oil에서는 약 $70 {\~} 90\%$의 phenoxyethanol이 유상에 존재하였다. 또한, 미생물에 대한 항균력도 phenoxyethanol이 수상에 많이 존재할수록 증가하는 경향을 나타내었다. 따라서, 제형 내 oil tomposition을 변화시킴으로써 phenoxyethanol의 사용량을 줄일 수 있을 뿐만 아니라, 피부 투과를 감소시켜 보다 피부 자극이 적은 저자극 방부시스템 개발이 가능하리라 보여 진다. 첨가하여 제조한 curd yoghurt는 저장성과 관능적인 면에서 우수한 상품적 가치가 인정되는 새로운 기능성 신제품의 개발에 기여할 수 있을 것으로 사료되었다. 여자의 경우 0.8이상이 되어서 심혈관계 질환의 위험 범위에 속하는 수준이었다. 삼두근의 두겹 두께는 남녀 각각 $20.2\pm8.58cm,\;22.2\pm4.40mm$으로 남녀간에 유의한 차이는 없었다. 조사대상자의 식습관 상태는 전체 대상자의 $84.4\%$가 대부분이 하루 세끼 식사를 규칙적으로 하고 있었으며 식사속도는 허겁지겁 빨리 섭취하는 경우가 남자는 $31.0\%$, 여자는 $21.4\%$로 나타났고 이들을 제외한 나머지 사람들은 보통 속도 혹은 충분한 시간을 가지고 식사를 하였다. 평소 식사량은 조금 적게

• Tunnel and Underground Space
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• v.19 no.4
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• pp.287-303
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• 2009

Rock mass in Baekrokdam at the summit of Hallasan in Jeju island is composed of two volcanic rock types: Baekrokdam trachybasalt at the eastern region and Hallasan trachyte at the western region. On-going rockfall and subsequent collapse of Baekrokdam wall rock are closely linked to the weathering of trachyte distributed in the western region of Baekrokdam. Samples of Hallasan trachyte showing different weathering grades had been collected and the polarizing microscopic observation, X-ray diffraction analysis and analysis for chemical weathering had been conducted. Formation of secondary minerals, especially clay minerals, by chemical weathering has not been identified, but the change of chemical weathering indices indicated that chemical weathering process had been proceeded to the degree for increasing and decreasing the contents of some chemical components. Changes in physical and mechanical rock properties due to weathering has also been examined. Artificial weathering test of freezing-thawing reveals that the process of crack initiation and propagation deteriorated the mechanical characteristics of Hallasan trachyte and $D_B$ = 1.5 or porosity = $20{\sim}21%$ would be the ultimate limiting value induced by the mechanical weathering processes.

• The Journal of Engineering Geology
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• v.9 no.3
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• pp.207-225
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• 1999

Twenty water samples (eleven groundwater and nine geothermal water samples) were collected to elucidate hydrogeochemical characteristics of the groundwater and geothermal water in the Dongrae hot-spring area and its vicinity. Major and minor elements were analyzed for ground and geothermal water samples. Physicochemical properties of the groundwater and the geothermal water were examined and chemical composition of the two waters were compared. Factor and correlation analyses were carried out to simplify the physicochemical data into grouping some factors and to find interaction between them. The groundwaters belong to $Ca-HCO_3$ type, while the geothermal waters belong to Na-Cl type. The Na and Cl concentrations in the Dongrae hot-spring area are higher than those of other granite areas in South Korea. The Na/Cl weight ratio ranges from 0.7 to 1.3 for the geothermal waters. On the phase stability diagram groundwaters fall effectively in the field of stability of kaolinite, while geothermal waters fall in the stability field of microcline or kolinite depending on the chemical composition system. Based on the Na-K, Na-K-Ca and Na-K-Ca-Mg geothermometers, the geothermal reservoir is estimated to have equilibrium temperature between 115 and $145^{\circ}C$.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.481-486
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• 2020

To evaluate geochemical characteristics of surface sediments in Samcheok Port, the distribution characteristics of particle sizes, organic matters and heavy metals were investigated. The sediments showed a mixed property of sand, silt, and clay, however fine-grains dominated at the inner port and coarse-grains dominated at the outer port. The organic (COD, TOC, and IL) contamination of the sediment at the inner port were higher than that of the outer port, and the concentrations of total nitrogen and total phosphorus at the inner port was higher than those of the outer port. Also, heavy metals contamination of surface sediments at the inner port was higher than those of the outer port (except for As). From the results of high organic matter concentrations and C/N ratio at the inner port, it is considered that the contamination of organic matters was mainly derived from the land. The correlation analysis among the particle size, chemical composition, and heavy metals resulted in high correlation between silt-clay and heavy metals, and between organic matters and heavy metals. The sequential extraction results of heavy metals showed the sum of exchangeable, carbonate, and oxide fractions of Ni, Zn, Cu, Pb, Cd, and As were 14.8, 49.8, 39.1, 32.2, 51.8 and 26.6%, respectively.

• The Journal of the Petrological Society of Korea
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• v.26 no.4
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• pp.311-325
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• 2017

Peridotite xenoliths in middle Miocene alkaline basalt from the Mt. Baekdu area are mainly anhydrous spinel lherzolites, displaying coarse-grained protogranular texture. These xenoliths have late-stage secondary orthopyroxene replacing olivine as the metasomatic mineral and glass formed along the grain boundaries. The studied xenoliths are characterized by the high $Mg{\sharp}[=100{\times}Mg/(Mg+Fe_{total})$ atomic ratio] of olivine, orthopyroxene and clinopyroxene (89~92) and the $Cr{\sharp}[=100{\times}Cr/(Cr+Al)$ atomic ratio] of spinel (10~29). Based on major-element data, the studied xenoliths are similar to those from the abyssal peridotites. Clinopyroxenes of the xenoliths are mostly enriched in incompatible trace elements, exhibiting two types of REE patterns: (1) LREE-depleted with $(La/Yb)_N$ of 0.1~0.2 and $(La/Ce)_N$ of 0.4~0.8. (2) LREE enriched with $(La/Yb)_N$ of 2.2~3.8 and $(La/Ce)_N$ of 1.2~1.6. The calculated equilibrium temperatures and oxygen fugacities resulted in $920{\sim}1050^{\circ}C$ and ${\Delta}fO_2(QFM)=-0.8{\sim}0.2$, respectively. It is suggested that the Mt. Baekdu peridotite xenoliths represent residues left after variable degrees of melt extraction(less than 15 vol%), which was subsequently subjected to different degrees of modal/cryptic metasomatism by silica- and LREE-enriched fluids (or melts).