• Economic and Environmental Geology
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• v.31 no.3
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• pp.201-213
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• 1998

From the Jungwon and Munkyeong areas which are among the famous producers of the carbonate-type groundwaters in Korea, various kinds of natural waters (deep groundwater, shallow groundwater and surface water) were collected between 1996 and 1997 and were studied for hydrogeochemical and environmental isotope (${\delta}^{34}S_{so4}$, ${\delta}^{18}O$, ${\delta}D$)systematics. Two types of deep groundwaters (carbonate type and alkali type) occur together in the two areas, and each shows distinct hydrogeochemical and environmental isotope characteristics. The carbonate type waters show the hydrochemical feature of the 'calcium(-sodium)-bicarbonate(-sulfate) type', whereas the alkali type water of the 'sodium-bicarbonate type'. The former type waters are characterized by lower pH, higher Eh, and higher amounts of dissolved ions (especialJy, $Ca^{2+}$, $Na^{+}$, $Mg^{2+}$, $HCO_3{^-}$ and $SO_4{^{2-}}$). Two types of deep groundwaters are all saturated or supersaturated with respect to calcite. Two types of deep groundwaters were both derived from pre-thermonuclear (about more than 40 years old) meteoric waters (with lighter 0 and H isotope data than younger waters, i.e., shallow cold groundwaters and surface waters) which evolved through prolonged water-rock interaction. Based on the geologic setting, water chemistry, and environmental isotope data, however, each of these two different types of deep groundwaters represents distinct hydrologic and hydrogeochemical evolution at depths. The carbonate type groundwaters were formed through mixing with acidic waters that were derived from dissolution of pyrites in hydrothermal vein ores (for the Jungwon area water) or in anthracite coal beds (for the Munkyeong area water). If the deeply percolating meteoric waters did not meet pyrites during the circulation, only the alkali type groundwaters would form. This hydrologic and hydrogeochemical model may be successfully applied to the other carbonate type groundwaters in Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.206-213
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• 2013

Glass eels (Anguilla japonica) are caught in the west coast of Korea on their migratory route from the breeding grounds in the Mariana Trench along the North Equatorial Current and the Kuroshio Current. To identify the food source of natural glass eels, we analyzed the stable C and N isotopes of glass eels caught in April 2012 and investigated possible food sources in the survey area. In particular, with respect to the stable C and N isotopes of particulate organic matter, we extended the surveying area to the northern parts of East China Sea as well as the west coast of Korea. The stable C and N isotope ratios of the glass eels caught in the west coast were found to be $-20.7{\pm}0.1$‰ and $5.0{\pm}0.2$‰, respectively. The stable C and N isotope ratios of the particulate organic matter in the west coast of Korea, in which the glass eels are assumed to eat the particulate organic matter as food source, were estimated to be $-24.0{\pm}0.3$‰ and $2.8{\pm}0.4$‰, respectively. Similar data were obtained from the northern part of the East China Sea, $-24.5{\pm}0.5$‰ and $0.8{\pm}0.3$‰. The stable isotope ratios showed values differing from the stepwise increasing rates up the food web in natural aquatic ecosystem, showing that particulate organic matter in the west coast of Korea and East China Sea was not served as the glass eels food source. This result suggested that the glass eels caught in the west coast might not assimilate nutrition from the marine environment during long migration.

• Economic and Environmental Geology
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• v.35 no.1
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• pp.1-12
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• 2002

Manus Basin, located in the equatorial western Pacific, is a back arc basin formed by collision between the IndoAustralian and the Pacific Plates. The basin is host to numerous hydrothermal vent fields and ore deposits. The basement rocks of the Manus Basin consist primarily of dacite and basaltic andesite. Some of the minerals that form the hydrothermal chimneys that were dredged on the Manus basin include pyrite, chalcopyrite, marcasite, sphalerite and galena. The chimneys can be classified into chalcopyrite dominant Cu-rich type and sphalerite dominant Zn-rich type. The concentration of Zn shows good positive correlation with that of Sb, Cd and Ag. The content of Cu, on the other hand, positively correlates with that of Mo, Mn and Co. For samples that were taken from Zn-rich chimney, a strong positive correlation is found between Au and Zn contents. The chimney also shows enrichments of Cd, Mn and Sb. On the other hand, the samples from Cu-rich chimney exhibit strong correlation among Au, Zn and Pb, and are enriched in Mo and Co concentration. Average contents of Au in Cu-rich and Znrich chimneys were 15.9 ppm and 29.0 ppm, respectively. Because of high concentration of Au with Ag and Cu, the ore deposit have high economic potential. Homogenization temperatures and salinities of fluid inclusions in anhydrite and amorphous silica from Zn-rich chimney are estimated to be l74-220$^{\circ}$C and 2.7-3.6 equiv. wt. % NaCI, respectively. These value suggest that ore forming processes were occurred at around 200$^{\circ}$C and that the oxygen fugacity changed from 2: 10$^{-39.5}$bar to -s: 10$^{-40.8}$bar and the sulfur fugacity from -s: 10$^{-14.7}$bar to 10$^{-13.4}$bar during the process. It appears that the temperature at which the ores formed on Cu-rich chimney was higher than that on Zn-rich chimney.

• Economic and Environmental Geology
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• v.34 no.4
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• pp.395-415
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• 2001

In the Singok area, western part of Chungcheongnam-Do, two ultramafic ma~ses, Singok mass and Kaewol mass, occur as isolated lenticular bodies in the Precambrian Kyeonggi gneiss complex. The masses extend for several hundred meter to NNE direction, parallel to the main fault line of this area. The rocks are dunite and harzburgite, but partially and absolutely serpentinized. They dominantly show porphyroclastic and recrystallized textures with equigranular-mosaic and protogranular textures. In spite of differences among the alteration and metamorphism, the ultramafic masses are characterized by varying amounts of high fosteritic olivine ($Fo_{0.88-0.93}$), magnesian pyroxene ($En_{0.93-0.97}$), and tremolitic to tschermakitic hornblende with minor spinel, serpentine, chlorite, calcite, magnetite, phlogopite and talc. It is compared with adjacent gneiss complex containing amphibole, biotite, plagioclase, alkali-feldspar and quartz. Geochemically, these rocks show high magnesium number (Mg>90.38), and transitional element (Ni=595-2480, Cr==IOlO-4400, Co=36-120 ppm), low alkali element ($Na_{2}O$<0.3, $K_{2}O$<0.11, $Al_{2}O_3$<2.95 wt%) and depleted incompatible element contents, which is compared with adjacent rocks (Mg < 83.69, $Na_{2}O$=1.02-3.42 wt%, $K_{2}O$=O.67-5.65 wt%, $Al_{2}O_3$=9.15-16.86 wt%, Ni < 435 ppm, Cr < 1440 ppm, Co<59 ppm, enriched incompatible element contents). Overall characteristics of ultramafic rocks from the Singok and Kaewol masses are similar to the those of adjacent ultramafic bodies in Chungnam with worldwide orogenic related Alpine type ultramalic rocks. Calculated geothermometries suggest that the ultramafic rocks have experienced metamorphism in the condition ranging from the greenschist facies to granulite facies.

• Economic and Environmental Geology
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• v.45 no.6
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• pp.599-622
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• 2012

The phase I soil geochemical exploration was carried out targeting around Chau Binh area far from about 14 km with southeastern direction from Quy Chau within Nghe An province. The interval of sampling are horizontal 300 m with 14 line and longitudinal 500 m with 15 line, resulting in 194 soil samples. Based on the result of the phase I soil geochemical exploration, the phase II detailed pitting survey was carried out targeting the grid point with high TREO content, resulting in 56 soil samples within 7 pits. The geology of survey area are consisted of Ban Chieng biotite granite complex and Dai Loc gneissic granite complex intruding Bu Khang formation comprising of schist, gneiss and limestone. Main mineralization in the study area have the characteristics of occurrence with tin, ruby and REE-bearing monazite(about 300 g/t) and xenotime(about 10 g/t) to be thought as occurring at the alteration zone of granite complex. In order to elucidate the source rock of monazite and xenotime confirmed from heavy sand, soil geochemical exploration was carried out. As a analysis result with ICP-MS on the soil samples from the phase I soil geochemical exploration, total REE oxide content of background amount to about 2 times of crustal abundance, enriching the heavy rare earth(about 2 times) and light rare earth(about 1.84 times). As a analysis result with ICP-MS on the soil samples from the phase II soil detailed pit survey, we identified outcrop considering as economic ore body at the grid point 4-7 pit with N40W attitude. As a synthetic consideration on the phase I soil geochemical exploration and phase II detailed pit survey, we tentatively designated areas considering as the extension of economic ore body with REE anomaly. In the near future, we have the plan to carry out the geophysical exploration and test drilling targeting the interval anticipated to the economic ore body.

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.233-244
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• 2012

Goseong bay, located in southeast sea of Korea with an area of 2,100 ha, is a semi-enclosed bay well-known for oyster farming cultured in an extended range of 148 ha. The objective of this study is to provide the fundamental data in order to manage the effective sea area. A total 26 of surface sediment were collected from Goseong bay to evaluate their sedimentary environment and heavy metals. The loss on Ignition (LOI), C/N ratio, acid volatile sulfide (AVS) and heavy metals were analyzed. loss on ignition (LOI) of surface sediment range from 1.00% to 3.03% (average 2.00%). The carbonate content ranges from 0.52% to 4.29% (average 2.37%). C/N ratio of organic matter showed that most part of organic matter comes from neighboring continent. Acid volatile sulfide (AVS) value of surface sediment from 0.02 mg/g to 1.43 mg/g (average 0.24 mg/g). A ten element of surface sediments (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, V, Zn) were calculated by enrichment factor (Ef) and the results show that some areas are highly polluted with respect Cu and Hg. The correlation matrix displays the existence of remarkable levels of correlation with both positive and negative values among different variable pairs. LOI and AVS showed both positive values. LOI and AVS values falls under 2% and 1%. Therefore, Goseong bay showed good in quality of sediment.

• Economic and Environmental Geology
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• v.22 no.1
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• pp.35-63
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• 1989

Geochemical characteristics of the Guryongsan (Ogcheon) uraniferous black slate show that this is an analogue to the conventional Chattanooga and Alum shales in occurrences. Whereas, its highest enrichment ratio in metals including uranium, among others, is explained by the cyclic sedimentation of the black muds and quartz-rich silts, and the uniform depositional condition with some what higher pH condition compared to the conditions of the known occurrences. The cyclic sedimentation, caused by the periodic open and close of the silled basin, has brought about the flush-out) of the uranium depleted water and the recharge with the new metal-rich sea water, which consequently contributed to the high concentration of metals in mud. The metal-rich marine black muds, which mostly occur in the early to middle Palaeozoic times, is attributed by the geologic conditions which related to the atmospheric oxygen contents, and these are scarcely met in the late Precambrian and/or with the onset of Palaeozoic era in the geologic evolution of the earth.

• Journal of Preventive Medicine and Public Health
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• v.35 no.2
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• pp.141-146
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• 2002

Objectives : This study was peformed in order to assess the incidence of hypertension based on two-years follow-up of a rural hypertension-free cohort in Korea. Methods : The study cohen comprised 2,580 subjects aged above 20 (1,107 men and 1,473 women) of Chung-Song County in Kyungpook Province judged to be hypertensive-free at the baseline examination in 1996. For each of two examinations in the two-year follow-up, those subjects free of hypertension were followed for the development of hypertension to the next examination one year (1997) and two years later (1998). The drop-out rate was 24.7% in men and 19.6% in women. Hypertension was defined as follows 1) above mild hypertension as a SBP above 140 mmHg or a DBP above 90 mmMg,2) above moderate hypertension as a SBP above 160 mmHg or a DBP above 100 mmHg or when the participant reported having used antihypertensive medication after beginning this survey. Results : The age-standardized incidence of above mild hypertension was 6 per 100 person years (PYS) in men and that of above moderate hypertension was 1.2. In women, the age-standardized rate for above mild hypertension was 5.7 and 1.5 for above mild and moderate hypertension, respectively. However, the rates of incidence as calculated by the risk method were 4.8% and 1.0% in men and 4.6%, 1.2% in women, respectively. In both genders, incidence was significantly associated with advancing age(p<0.01), In men, the incidences of above moderate hypertension by age group were 0.5 per 100 PYS aged 20-39, 0.7 aged 40-49, 1.7 aged 50-59, 3.6 aged 60-69, and 5.8 aged above 70(p<0.01). In women, those the incidence measured 0.6 per 100 PYS aged 20-39, 1.8 aged 40-49, 1.3 aged 50-59, 3.3 aged 60-69, and 5.6 aged above 70(p<0.01). After age 60, the incidence of hypertension increased rapidly. Conclusions : The incidence data of hypertension reported in this study may serve as a reference data for evaluating the impact of future public efforts in the primary prevention of hypertension in Korea.

• The Journal of the Petrological Society of Korea
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• v.20 no.2
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• pp.77-98
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• 2011

The igneous complex consisting of mangerite and gabbro in the Odaesan area, the eastem part of the Gyeonggi Massif, South Korea, intruded early Paleo-proterozoic migmatitic gneiss. The mangerite is composed of orthopyroxene, clinopyroxene, amphibole, biotite, plagioclase, pethitic K-feldspar, quartz. The gabbro has similar mineral assemblage but gabbro has minor amounts of amphibole and no perthitic K-feldspar. The gabbro occurs as enclave and irregular shaped body within the mangerite, and the boundary between the mangerite and gabbro is irregular. Leucocratic lenses with perthitic K-feldspar are included in the gabbro enclaves. These textures represent mixing of two different magmas in liquid state. SHRIMP U-Pb zircon age dating gave $234{\pm}1.2$ Ma and $231{\pm}1.3$ Ma for mangerite and gabbro, respectively. These ages are similar with the intrusion ages of post collision granitoids in the Hongseong (226~233 Ma) and Yangpyeong (227~231 Ma) areas in the Gyeonggi Massif. The mangerite and gabbro are high Ba-Sr granites, shoshonitic and formed in post collision tectonic setting. These rocks also show the characters of subduction-related igneous rock such as enrichment in LREE, LILE and negative Nb-Ta-P-Ti anomalies. These data represent that the mangerite and gabbro formed in the post collision tectonic setting by the partial melting of an enriched lithospheric mantle during subduction which occurred before collision. The heat for the partial melting was supplied by asthenospheric upwelling through the gab between continental and oceanic slabs formed by slab break-off after continental collision. The distribution of post-collisional igneous rocks (ca. 230 Ma) in the Gyeonggi Massif including Odaesan mangerite and gabbro strongly suggests that the tectonic boundary between the North and South China blocks in Korean peninsula passes the Hongseong area and futher exteneds into the area between the Yangpyeong-Odaesan line and Ogcheon metamorphic belt.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.553-566
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• 1997

Origin, behavior and enrichment of environmental toxic elements from the Deokpyeong area were investigated on the basis of major, trace and rare earth element geochemistry. Coaly metapelites of the Deokpyeong area are subdivided into grey phyllite, dark grey phyllite, coaly slate and black slate, which are interbedded along the Ogcheon Supergroup. The coaly slate had been mined for coal, but mining is closed. The coaly and black slates are lower contents of $SiO_2$ and $Al_2O_3$, and higher contents of LOI, CaO, $Na_2O$ and BaO as compared with the phyllitic rocks. Rare earth elements are highly enriched in the coaly and black slate. Average compositions (ppm) of minor and/or environmental toxic elements in the coaly and black slate are revealed as As=127, Ba=30,163, Cd=18, Cr=740, Cu=84, Mo=378, Pb=43, Sb=12, Se=44, U=144, V=8,147 and Zn=292, which are extremely high concentrations than those in the NASC compositions. Major elements (average enrichment index; 5.34) in the coaly metapelites are mostly depleted, excepting $P_2O_5$ and BaO, normalized by NASC. Rare earth elements (average enrichment index; 1.48) are enriched in the coaly slate. On the basis of NASC, minor and/or environmental toxic elements in the coaly metapelites were strongly enriched of all the elements with the exception of Co, Cs, Ni and Sr. Average enrichment index of trace elements in coaly metapelite is 31.51 (coaly slate; 51.94 and black slate; 15.46). Especially, enrichment index of potentially toxic elements (As, Ba, Cr, Cu, Mo, Ni, Sb, Se, U, V and Zn) of the rock is 46.10 (grey phyllite; 7.15, dark grey phyllite; 4.77, coaly slate; 88.96 and black slate; 22.11). These coal formations were deposited in basin of boundary between terrestrial and marine environments deduced to carbon, sulfur (C/S=2.2 to 275.7), trace and rare earth elements characteristics. Irregular behavior and dispersion between major, minor and rare earth elements of those metapelites indicates a variable source materials, incomplete mixing of differential source and/or reequilibrium of diagenesis and metamorphism.