• 한국지구물리탐사학회:학술대회논문집
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• 2004.08a
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• pp.104-117
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• 2004

Dmitri Donskoi, which went down during the Russo-Japanese War occurred 100 years ago, was found by using geophysical exploration techniques at the 400 m water depth of submarine valley off Jeodong of Ulleung Island. In the submarine area with the rugged seabed topography and volcanic seamounts, in particular, the reliable seabed images were acquired by using the mid-to-shallow Multibeam exploration technique The strength of corrosion (causticity) of the sunken Donskoi, measured by the electrochemical method, decreased to 2/5 compared with the original strength.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.547-561
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• 2005

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a ffw previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about $28\%$ of the shallow groundwaters exceeded the Bangladesh drinking water standard, $50{\mu}g/L$, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of $SO_4^{2-}$ and $NO_3^-$, and high contents of dissolved organic carbon (DOC) and $NH_4^+$ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciatiion during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about $1\%$ of grounwaters have concentrations higher than $10{\mu}g/:L.$ However, it was revealed that $19.3\%$ of mineral waters, and $7\%$ of tube-well waters from Nonsan and Geumsan areas contained As concentrations above $10{\mu}g/:L.$. Also, percentages exceeding this value during detailed groundwater quality surveys were $36\%\;and\;22\%$ from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.

• Economic and Environmental Geology
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• v.46 no.2
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• pp.93-104
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• 2013

Daejiguksaptapbi (Tapbi) is a memorial stele which is inscribed with personal history of a state preceptor, Daejiguksa Beopkyeong. The Tapbi comprises tortoise-shaped pedestal, dragon top and body stone, and the body stone is remained in 255 pieces by excavation in Samcheonsaji temple site of Seoul. The Tapbi is composed of tuffaceous breccia for the body, coarse-grained pink feldspar granite for the pedestal and fine-grained granite for the top. As a result of geological survey to find a rock provenance of the Tapbi rock, the tuffaceous breccia is found in the banks of Gangwha straits, and the pink feldspar granite and fine-grained granite are found around the temple site in Mt. Bukhansan. Each rock shows similarities to the Tapbi in lithology and mineralogy. Also, geochemical data of major, some trace and rare earth elements verify their cognation in each rock type. It can be interpreted that the provenance of the body stone is distant as Gangwha area, and the provenance of the pedestal and top stones are near the temple site. The results can be utilized to restore the Tapbi by using the same rocks.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.423-433
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• 2017

Korea Institute of Geoscience and Mineral Resources and Department of Geological Survey and Mineral Exploration in Myanmar have explored the Kalaymyo chromitite deposit, Myanmar since 2013. It is now necessary to find a geochemical indicator for efficient mineral exploration in the future and building a 3D geological model for this ore deposit. Mantle podiform chromitite is a major type of Cr ore in this region, which is considered to be formed by mantle-melt interaction beneath the mantle-crust boundary of oceanic lithosphere. In this study we measured major element composition of spinels in harzburgite, dunite and chromitite, and examined the hypothesis that spinel Cr#(molar Cr/(Cr+Al)${\times}$100) can be used as a geochemical indicator in exploration for the Kalaymyo chromitite. The results show that there is a clear correlation between spinel Cr# and distribution of chromitite. The spinel Cr# of harzburgite increases with decreasing the distance from the chromitite bodies. The spinel composition is also closely associated with texture and occurrence of spinels. The high Cr# spinels (30-48) are subhedral to euhedral and enclosed by olivine whereas the low Cr# spinels (16-27) are anhedral and commonly associated with pyroxenes. Often the low Cr# spinels show symplectite intergrowths with pyroxenes, indicating their residual nature. These petrological and geochemical results suggest that the high Cr# spinels have resulted from mantle-melt interaction. We suggest that spinel Cr# can be used as a geochemical indicator for Cr ore exploration and as one of critical factors in 3D geological model in the Kalaymyo chromitite deposit.

• Journal of the Korean Geophysical Society
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• v.5 no.4
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• pp.337-344
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• 2002

The alluvial deposits along meandering rivers can be used as an artificial aquifer for infiltration of river waters. Internal heterogeneity of the alluvial deposits is a prerequisite information for the development of alluvial groundwater because vortical and lateral movement of alluvial ground water depends on the internal heterogeneity The internal heterogeneity due to variations in channel behavior can be delineated using GPR survey, GPR profiles for the point bar deposits near Buyeo county reveals two different stratigraphic units: the lower inclined heterogeneous strata and the upper horizontally stratified strata. The upper unit is largely indicative of vertical accumulation by overbank floods within a floodplain, whereas the lower one represents typical point bar deposits formed by lateral accretion. The stratigraphic variation in the heterogeneity shows that GPR survey is a useful and necessary investigation method for the development of alluvial ground water.

• The Journal of the Petrological Society of Korea
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• v.1 no.2
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• pp.104-123
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• 1992

We present petrography, mineral chemistry of amphibole and plagioclase, and major and trace element chemistry for the Ogcheon metabasites occurring in the Poun and Mungyong areas to understand metamorphism, and to define chemical characteristics of parental rocks and their implication for tectonic environment. The Ogcheon metabasites often preserve relict igneous textures, although no primary phases are observed. They are mainly composed of amphibole (actinolite+hornblende)+plagioclase+epidote+chlorite+sphene+opaque oxides, indicating epidote amphibolite facies metamorphism. Coarse-grained amphiboles frequently have actinolitic composition in the core, and hornblende along the margin and cleavage, which can be interpreted either as miscibility gap or as result of polymetamorphism. Although presumed polymetamorphic events in the Ogcheon supergroup favor the latter possibility, further metamorphic studies are necessary to solve the problem. Amphibole and plagioclase chemistries suggest greenschist (epidote-amphibolite, if miscibility gap is present) to amphibolite facies metamorphism of possibly medium pressure. The major and trace element data of whole rocks indicate that the Ogcheon metabasites are transitional to tholeiitic basalts belonging to within-plate environment. Absence of evidences indicating deep sea environment suggests that the Ogcheon metabasites emplaced in an intra-cratonic, possibly rift environment which failed to proceed to an oceanic rift. Chemical variation of the metabasites toward a granitic pluton indicates K loss closer to the pluton, suggesting that caution should be taken when K is involved in a discussion.

• Economic and Environmental Geology
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• v.40 no.4
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• pp.419-443
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• 2007

Recently, the branch-out of foreign companies into domestic markets through M&A and the opened followed by the Free Trade Agreement(FTA) with America have made the environmental site assessments of specific site more necessary. In this study, through case study of conducting actual environmental site assessment by use of a toolbox approach at a large scale of chemical plant with various contaminants located in a coastal area, the problems of guideline of domestic environmental assessment of soil were complemented. And an efficient and economical assessment was achieved. All six steps such as basic investigation, environmental site history survey, sampling and analysis, installation of monitoring wells and hydrogeological survey, and data interpretation were conducted in this study. All results of document survey, geological lineament analysis, field geology survey of surrounding area, geophysical prospecting of the site, hydraulic conductivity, measurement of groundwater flow rate and direction, sampling and analysis at each step were associated and estimated as an integrated tool box approach. As a consequence of this study, toolbox approaches were very useful techniques for contamination level and site characterization of subsurface media. The given conditions to conduct a basic survey for domestic soil environment assessment of site by use of existing documents, as well as interviews with the owner/manager/user of all adjacent properties and thorough review of all practically reviewable records pertaining to the property and surrounding properties within "Guideline for Soil Environment Assessment" radii are very poor. As a result, the application of toolbox approach in the environment site assessment of site is not only more efficient and economical, but also could be very useful assessment to integrate the soil and groundwater contamination.

• 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).

• Economic and Environmental Geology
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• v.46 no.5
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• pp.455-468
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• 2013

We performed reconnaissance survey on Dashinchilen Nb-Ta REE area and Sant Cu area which are located in southeastern part of Khangai rare metals mineralized belt. In Dashinchilen area, Nb and Ta have been found in pegmatitic granite that is largely distributed in the survey area and muscovite in pegmatite which is an intrusion in paleozoic sedimentary rocks which are mostly composed of sandstone. While grades of Nb and Ta are not high, an outcrop that has high Th and U contents (542 ppm of Th and 56.9 ppm of U) has been found. Average and maximum REE contents in the survey area is three times and seven times, respectively, larger than average REE contents in the crust of the Earth. In Sant area, copper oxides such as malachite has been found in quartzite in paleozoic sedimentary rocks. A sedimentary rock formation that has high grade of Mn (12.4-34.6 %) has been found in the survey area. This sedimentary rock formation is the same formation with that of Ugii Nuur Fe-Mn mineralization which is located about 200 km northwest of the survey area. Average and maximum REE contents in the survey area is two and half times and seven times, respectively, larger than average REE contents in the crust of the Earth. According to the factor analysis for the data of the geochemical analysis, Nb and Ta in Dashinchilen area are highly correlated with muscovite and Cu in Sant area is highly correlated with Mo, Sn, and Bi. Furthermore, the factor analysis results show that Fe in Sant area was deposited with rare earth elements.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.35-44
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• 2006

Various geophysical methods and geological survey were applied for prospecting of geothermal resources and the attitude of volcanic body at northern part of Kumseongsan, Euiseong. They include magnetic, self-potential, radioactive and resistivity methods, temperature logging near the earth's surface and geological survey. The results of this study are summarized as follows. Various geophysical anomalies is related to the geologically Cretaceous conduit. Anomalies of resistivity and temperature logging seem to be related to the geological structure and terrestrial heat. Small radioactive and self-potential anomalies seem to be associated with chemical character of rocks. The sedimentary rocks dip steeply toward the volcanic rocks, aquifuge. Ideal geological structure for bearing ground water and geothermal resources was founded in the study area. The study area and the adjacent two hot springs area consist of Cretaceous sedimentary and volcanic rocks, and have similar geology.