• Journal of Conservation Science
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• v.20
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• pp.55-65
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• 2007

Black surface layers collected from stone pagodas were analyzed to study the effects of carbon compounds on the blackening of stone surface layer. The total amounts of carbon was measured through elemental analyser. Organic and elemental carbon were measured by combustion ihrornatographic $CO_2$ determination after elimination of carbonates carbon with acid treatment. The elemental carbon concentration in the black surface layer measured 0.52wt.%. This value is not sufficient to explain the complete blackening of stone surface. To trace the origin of carbon in black surface layer on the stone pagoda, aerosol samples for PM 10 were collected at the near sites of the pagoda. The major components of them were soluble ions(42.8wt.%), carbon(38.4 wt.%) and crustal matter(16wt.%). From the high content(13wt.%) of elemental carbon in aerosol ran be deduced that it may be a prime origin for the elemental carbon in the black surface layer on the stone pagoda. The crustal matter in aerosol can be also a origin of silicate mineral in black surface layer and plays a important role in the darkening of black surface layer.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.483-493
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• 1996

The tectonic environment and source characteristics of the Daebo granitic batholith in the central Ogcheon Belt were investigated based upon major and trace element geochemistry. The batholith is comprised of three granite types; a biotite granite (DBBG), K-feldspar megacryst-bearing biotite granite (DBKG), and a more mafic granodiorite (DBGD). The variations of Na and K in the granites can not be explained by simple fractional crystallization from the same primary magma. The irregular behavior of these alkali elements indicates a variety of source materials or incomplete mixing of different source materials. The large ion lithophile (LIL) element enrichment and low Ta/Hf ratios of the granites are typical characteristics of normal, calc-alkaline continental arc granitoids. Based upon REE patterns of the granites, it seems to be unreasonable to regard the felsic DBBG as a late stage differentiate formed by residual melts after the fractionation of major constituent minerals of the more mafic DBGD. Inconsistent variations in ${\varepsilon}_{Nd}(t)$ and LIL element concentrations of the granites preclude a mixing model between primitive melt and LIL element-enriched upper crustal materials. The irregular geochemical variation of the granites is taken to be largely inherited from an already heterogeneous source region.

• The Journal of the Petrological Society of Korea
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• v.18 no.3
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• pp.255-267
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• 2009

The intrusive rocks in the Hudongri area, Chuncheon located in central Gyeonggi Massif consist of gabbroic diorite and diorite. K-Ar age of biotite separated from diorite sample records middle Triassic age of 228 Ma. The intrusives are characterized by enrichment of MgO, Ni and Cr as well as large ion lithophile elements such as Sa and Sr, which is indicative of derivation of magma from enriched mantle. The intrusives also have enriched Sr-Nd isotopic compositions, which appear to result from a long-term incompatible element enriched mantle source with an effect of crustal contamination. Occurrence of abundant hydrous minerals such as amphiboles and biotite rather than anhydrous minerals of pyroxene and olivine in mafic intrusive as well as being plotted in volcanic arc field in tectonic environment discrimination diagram indicate the mafic-intermediate intrusives in the Hudongri area, Chuncheon were derived from mantle material enriched by subduction.

• Economic and Environmental Geology
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• v.28 no.1
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• pp.19-24
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• 1995

Based upon the lead isotopic compositions of the galenas collected from Pb-Zn ore deposits distributed in the eastern and southern parts of the Gyeongsang basin, we investigated what kinds of source materials were involved in the formation of these ore deposits and compared the lead isotopic characteristics of these ore deposits with those of the ore deposits in the Taebaegsan area. The isotopic compositions of the common leads from Pb-Zn ore deposits in the Gyeongsang basin show the variation with the relatively limited range ($^{206}Pb/^{204}Pb=18.156{\sim}18.377$, $^{207}Pb/^{204}Pb=15.482{\sim}15.638$, and $^{208}Pb/^{204}Pb=37.953{\sim}38.605$). They are plotted on or below ore lead growth curve(Cumming & Richards, 1975) and average crustal lead evolution curve (Stacey & Kramer, 1975). In the plumbotectonic model IV(Zartman & Haines, 1988), they are plotted between the evolution curves of mantle and orogene. But the lead isotopic compositions of the common leads in the Taebaegsan area are plotted on and above upper crust curve. Considering the above-mentioned lead isotopic characteristics, the linear trend shown in the isotopic compositions of the common leads in the Gyeongsang basin can be considered as the mixing isochron between high radiogenic crustal materials such as the Ryongnam massif and low radiogenic materials derived from depleted mantle or materials with relatively low U/Pb and Th/U ratios.

• The Journal of the Petrological Society of Korea
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• v.14 no.3 s.41
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• pp.141-148
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• 2005

Lead isotopic compositions are analyzed from the sulfide minerals of the Yeonhwa, Janggun and Uljin deposits and from host limestone, intrusives, and basement rocks to reveal the source of Pb in these deposits. In the $^{206}Pb/^{204}Pb$ vs $^{207}Pb/^{204}Pb$ plot, Galenas from the Yeonhwa mine display relatively well defined positive linear array, similar to the Precambrian basement rocks of the Korean peninsula. A galena sample from the Uljin mine, Janggun limestone and the basement rocks also follow the variation of Yeonhwa mine. However, ore minerals from the Janggun mine, having relatively low $^{206}Pb/^{204}Pb$ values, reveal offset from such trend toward lower $^{207}Pb/^{204}Pb$ values. Considering the fact that Mesozoic igneous rocks and ores within the Gyeongsang basin display considerably lower $^{207}Pb/^{204}Pb$ values than basement rocks of the Korean peninsula, the deviation of Janggun ore minerals can be interpreted as to reflect mixing between leads from old continental crustal materials and from Mesozoic igneous rocks with more mantle signature. The lead of the Yeonhwa and Uljin mine, following trend of Precambrian basement rather well, seems to have been originated mostly from such basement. However, regarding that they occupy low $^{207}Pb/^{204}Pb$ side of the variation trend of the basement, the possibility of having some leads derived from the Mesozoic igneous rocks cannot be excluded.

• Economic and Environmental Geology
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• v.24 no.4
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• pp.447-463
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• 1991

Petrological and chemical studies of Precambrian dikes in the southern Lake Superior region were conducted with the objects of evaluating magma source and constraining models for the paleo-tectonic environment. Forty-six samples were analyzed for major, trace, and rare earth elements. Chemical data of the studied dikes are typical of continental tholeiites and showing iron-enrichment fractionation trend. With wallrock contamination carefully evaluated, a series of tectonic discriminating methods utilizing immobile trace elements indicate that the source magma was a high-Ti tholeiitic basalt similar to present-day T-type MORB. Effect of chemical contamination from wallrock assimilation accmulates with increasing differentiation. Evolved rocks show LREE enriched patterns and have enhanced levels of LIL elements (e.g., Rb, K, Ba, Th), but low levels of high field strength elements (e.g., Nb, P, Ti) with respect to their neighboring elements. It is suggested from this study that this enrichment possibly due to a combination of a feature inherited from the subcontinental lithosphere and crustal contamination. Geochemical signatures of these rocks are distinctively different from those of arc-related volcanics. Comparisons with chemistries of modern magmas show a pattern of overlap between Within-plate and ocean-floor characteristics, and chemical signatures of these rocks favor a model of intrusion into a crustal environment undergoing lithospheric attenuation.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.113-126
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• 2022

The tectonic history of the Chukchi Abyssal Plain in the Amerasia Basin, Arctic Ocean, has not been fully explored due to the harsh conditions of sea ice preventing detailed observation. Existing models of the tectonic history of the region provide contrasting interpretation of the timing of formation of the crust (Mesozoic to Cenozoic), crust type (from hyper-extended continental crust to oceanic crust), and formation process (from parallel/fan-shaped rifting to transformation faulting). To help determine the age of the oceanic crust, the geothermal gradient was measured at three stations in the south of abyssal plain at depth of 2,160-2,250 m below sea level. Heat flow measurement stations were located perpendicular to the spreading axis over a 40 km-long transect. In-situ thermal conductivity measurement, corrected by the laboratory test, gave observed marine heat flows of 55 to 61 mW/m². All measurements were taken during Arctic expeditions in 2018 (ARA09C expedition) and 2021 (ARA12C expedition) by the Korean ice-breaking research vessel (IBRV) Araon. Given the assumption of oceanic crust, the results correspond to formation in the Late Cretaceous (Mesozoic). The inferred age supports the hypothesis of formation activated by the opening of the Makarov Basin during the Late Mesozoic-Cenozoic. This would make it contemporaneous with rifting of the Chukchi Border Land immediately east of the abyssal plain. The heat flow data indicate the base of the gas hydrate stability zone is located 332-367 m below the seafloor, this will help to identify the gas hydrate-related bottom simulating reflector in the future seismic survey, as already identified on the Chukchi Plateau. Further geophysical surveys, including heat flow measurements, are required to increase our understanding of the formation process and thermal mantle structure of the abyssal plain.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.651-660
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• 2007

Acid drainage has been recognized as an environmental concern in abandoned mine sites for long time. Recently, the environmental and structural damage by acid drainage is a current issue in construction sites in Korea. Here, the author introduces the type of damages by acid drainage in construction sites and emphasizes the importance of geoscience discipline in solving the problem. Metasedimentary rock of Okcheon group, coal bed of Pyeongan group, Mesozoic volcanic rock. and Tertiary sedimentary and volcanic rocks are the major rock types with a high potential for acid drainage upon excavation in Korea. The acid drainage causes the acidification and heavy metal contamination of soil, surface water and groundwater, the reduction of slope stability, the corrosion of slope structure, the damage on plant growth, the damage on landscape and the deterioration of concrete and asphalt pavement. The countermeasure for acid drainage is the treatment of acid drainage and the prevention of acid drainage. The treatment of acid drainage can be classified into active and passive treatments depending on the degree of natural process in the treatment. Removal of oxidants, reduction of oxidant generation and encapsulation of sulfide are employed for the prevention of acid drainage generation.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.635-649
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• 2007

Geochemical composition, stable isotopes $({\delta}^{18}O,\;{\delta}D,\;{\delta}^{34}S)$ and noble gases(He, Ne and Ar) of nine hot spring water and three groundwater for five hot springs(Jukam, Hwasun, Dokog, Jirisan, Beunsan) from the Honam area were analyzed to investigate the hydrogeochemical characteristics and the hydrogeochemical evolution of the hot spring waters, and to interpret the source of sulfur, helium and argon dissolved in the hot spring waters. The hot spring waters show low water temperature ranging from 23.0 to $30.5^{\circ}C$ and alkaline characteristics of pH 7.67 to 9.98. Electrical conductivity of hot spring waters is $153{\sim}746{\mu}S/cm$. Groundwaters in this area were characterized by the acidic to neutral pH range$(5.85{\sim}7.21)$, the wide electrical conductivity range $(44{\sim}165{\mu}S/cm)$. The geochemical compositions of hot spring and groundwaters can be divided into three water types: (1) $Na-HCO_3$ water type, (2) Na-Cl water type and (3) $Ca-HCO_3$ water type. The hot spring water of $Ca-HCO_3$ water type in early stage have been evolved through $Ca(Na)-HCO_3$ water type into $Na-HCO_3$ type in final stage. In particular, Jurim alkaline(pH 9.98) hot spring water plotted at the end point of $Na-HCO_3$ type in the Piper diagram is likely to arrive into the final stage in geochemical evolution process. Hydrogen and oxygen isotopic data of the hot spring water samples indicate that the hot spring waters originated from the local meteoric water showing latitude and altitude effects. The ${\delta}^{34}S$ value for sulfate of the hot spring waters varies widely from 0.5 to $25.9%o$. The sulfur source of most hot spring waters in this area is igneous origin. However, The ${\delta}^{34}S$ also indicates the sulfur of JR1 hot water is originated from marine sulfur which might be derived ken ancient seawater sulfates. The $^3He/^4He\;and\;^4He/^{20}Ne$ ratios of the hot spring waters range from $0.0143{\times}10^{-6}\;to\;0.407{\times}10^{-6}\;and\;6.49{\sim}584{\times}10^{-6}$, respectively. The hot spring waters are plotted on the mixing line between air and crustal components. It means that the He gas in the hot spring waters was mainly originated from crustal sources. However, the JR1 hot spring water show a little mixing ratio of the helium gas of mantle source. The $^{40}Ar/^{36}Ar$ ratios of hot spring water are in the range from $292.3{\times}10^{-6}\;to\;304.1{\times}10^{-6}$, implying the atmospheric argon source.

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.123-134
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• 2012

Hydrochemical analyses, carbon isotopic (${\delta}^{13}C_{DIC}$) analyses, and noble gas isotopic ($^3He/^4He$ and $^4He/^{20}Ne$) analyses of the Dalki carbonate waters in the Chungsong area were carried out to elucidate their hydrochemical composition and to determine the source of $CO_2$ gas and noble gases. The carbonate waters have a pH of between 5.93 and 6.33, and an electrical conductivity 1950 to $3030{\mu}S/cm$. The chemical composition of all carbonate waters was Ca(Mg)-$HCO_3$, with a high Na content. The contents of Fe, Mn, and As in some carbonate waters exceed the limit stipulated for drinking water. The concentrations of major ions are slightly higher than those reported previously. The ${\delta}^{13}C_{DIC}$ values range from -6.70‰ to -4.47‰, indicating that the carbon originated from a deep-seated source. The $^3He/^4He$ and $^4He/^{20}Ne$ ratios vary from $7.67{\times}10^{-6}$ to $8.38{\times}10^{-6}$ and from 21.32 to 725.7, respectively. On the $^3He/^4He$ versus $^4He/^{20}Ne$ diagram, the noble gas isotope ratios plot in the field of a deep-seated source, such as mantle or magma. We therefore conclude that $CO_2$ gas and noble gas in the Dalki carbonate waters originated from a deep-seated source, rather than an inorganic $CO_2$ origin as suggested in a previous study.